ConstructionTopic.com» construction topic, construction safety

Home Construction; preparation, principals & methods

Keith Bray — Fri, 12 Mar 2010 19:25:44 +0000

Hello my name is Keith Bray; and I want to talk to you about Home Construction and some things that I hope will benefit you in the longrun and not a lot of rehashing of the same information, but I'll try to cover some old and new. However the first topic I'll cover is of major concern in the construction field and it wouldn't hurt at all for us to do some rehashing just to refresh if need be,and chew the cud so to speak.

Who is capable of giving good direction and advice to the layman; I have the answer to that! I can of course; I've worked in the construction field for over 40 years and I know a little about the subject. As also, I would imagine, you do too. You know what I'm talking about, especially if you have done any work in any field of construction.

I began this subject in my wordpress.com blog but it was never published for numerous reasons I don't care to enumerate at this point, but I'm looking forward to working with you all and hopefully to impart to you some things as I recall certain facts, processes and with some illustrations that will be helpful. So concerning my topics, I'd like to start from the ground and work my way up to the point when it's time to move in.

FIRST LAYING SOME GROUND WORK BEFORE CONSTRUCTION STARTS.

I will always; and forever stress one major point, and that point is the big safety word. SAFETY,SAFETY,SAFETYand MORE SAFETY! Safety this and safety that; safety, safety, safety.

It can't be stressed enough, as a matter of a proven fact. This cannot be over stressed and will benefit you immeasurably in the long run, especially when you are the owner of the work site or the supervisor or managing a job site where normally several crafts working altogether with equipment operators, 10 or more workers all in the same area. You would not want any mishaps.

Although the potential for something to go wrong always exist. You have the obligation to yourself and your employees to become proactive, and to take proper steps to minimize potential safety hazards and threats as much as possible. Most accidents happen because of a lack of safety training, which will prevent most unknowns from happening. If you and your workers are properly trained to recognized existing and non-existing hazardous conditions before they occur, steps can be taken to put in place certain preventativemeasures, such as; devices or personal protective equipment for example, to nullify or minumize potential hazardous conditions or threats.

TAKING PROPER STEPS TO BE SAFE

I suppose my first topic, I'll start with safety since you should be well grounded and absorbed in this construction workers topic, it would behoove anyone doing any work on a site where multiple dangers exist, and every one concerned should be actively involved, first of all for their own wellfare as well as there fellow employees.

On some smaller sites and all the large ones, a safety inspector is prone to show up at any time to inspect a job. Here first impressions go along way and depending on how many infractions he may find, he is liable to slap a work stoppage on your site and hit you with fines for noncompliance that are really costly. This is also in the scope of construction topics.

To start I will cover general construction topics and then go back and build on those topics with more specific detail.

BASIC SAFETY CONSTRUCTION TOPIC / Read on!

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Construction: Site Preperation

Keith Bray — Thu, 11 Mar 2010 19:22:50 +0000

Beginning at the Research phase: The site design and site planning process begin with the initial problem to be solved, here the planner works with a particular site, his work will involve things such as; site search and site feasibility study, preliminary design, site visit, building permits, factored estimate, design, interim financing and some estimates then organizing and controlling construction cost.

Construction topic 2

SITE ANALISIS

Site Analysis: The site survey will encompose an inventory completed as a preparatory step to site planning which involves research, analysis, and synthesis. Primarily gathering of physical data of a chosen site, and will consider the way to situate the building or layout and configure the orientation of the structure in relation to the landscape. This includes the layout of the site as defined by it's boundaries, property lines, zoning ordinances, natural grades and contours, and safety zones.

Location:Using aerial photographs, the site should be related to existing major roads or landmarks, this will help in the assessment, There should be documentation of distances from major places. You can do this by either walking or driving the distance yourself.

Neighborhood context: This type of information can typically be found at the Municipal Planning Department (MPD) of the site.

Size and Zoning:Site boundaries can be verified by contacting the county tax assessor's office. Zone classifications, setbacks, height restrictions, allowable site coverage, uses, and parking requirement are obtained by using the zoning classifications from a zoning map. Which you can get from the city planning office.

Legal:Typically legal information can be found from the deed to the property. The deed is held by the owner of the title insurance company. Property description, present ownership, and the governmental jurisdiction the site is located in, and the city and county is found in the deed.

Natural physical features:This information will be gained from topographical features of the site. A contour map is a map with contour lines, for example a topographic map that shows valleys, hills, and the steepness of the slopes. The contour line interval of a contour map, is the difference in elevation between successive contour lines. This map is obtained from the survey engineer. Drainage problems as well as natural existing features of trees, ground cover, ground features, and soil condition of the site should be observed from the map.

With that being said, Let's look at a few considerations. City dwelling of course has its pros and cons. A lot of people who live in the city would rather move to the country. Its a matter of choice. Everything in the city is within distance, schools, transit, law enforcement, proper disposal of sewage, libraries, theaters, concerts and the like. The catch word is convenience. The cons may be high real estate taxes, city land has become scarce and expensive, industrial emissions, vehicle exhaust, and a fast pace lifestyle.

Becoming a suburbanite is a consideration. Or a quick look at country living, wide open spaces, trees, hills forest, dirt roads, barbwire fences and acres and acres of farm land, open fields as far as the eye can see, some people feel really at peace with themselves in the country, personally I love the scenic view. The cons may be digging a well, far from town, long drives to work, no transit, and no police department,... etc. But others, need that close co-minggling in the crouds together, where everything is happening, fast pace lifestyle. Reasons for where we choose to live and the final determination of that choice will ultimately guide you to preparing the construction site.

Enough for now.

You can go to OSHA Soil Classification 1926 Sub-part P App 4 which shows a further breakdown and explanation of these classifications / Read on!

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Getting your ducks in line

Keith Bray — Wed, 10 Mar 2010 19:10:47 +0000

Building codes:you can obtain a copy of local building codes from the local building department. Let the Building Department know where your planning to build, and they can direct you to the proper agency that has jurisdiction over the site and how to get a copy. It is critical that your plan drawing specifically list the proper codes, your plans will have to be approved by the local governing body before submission and issuing of permits. You may also have a local architect or draftsman check your plans to ensure that they meet all the local requirements for the area.

Alrighty, you'll need to obtain:

Plot plan:The whole layout of the entire parcel with existing and the proposed structure, meters and bounds in accordance with regulations set as shown. Location to scale with setback dimension to the closets property lines. Dimension to foundation walls, septic tank, location to leach bed etc. In most cases you'll haft to have a certified licensed surveyor to certify a plot plan.

Floor plan: Your floor plan shows the size of the building from the upper view, living spaces, bedrooms, and the arrangements, the size and location of the windows and doors, the location of the electric, plumbing and heating systems.

Foundation plan:Shows the location with all the dimensions and sizes of the interior and exterior footings, walls, piers and includes footing height, width,and depth, type of re-bar and re-bar layout, and anchor bolts and spacing.

Elevation plan:Shows how each side of the house or structure will look. It shows both the finished exterior, the height, width and length dimensions are given. All the exterior openings, siding and trim details, finished grade, the roof and roofing material, style pitch and overhang of the eaves.

Framing plan: These plans will show the layout of plates, walls, studs, ceiling and floor joist and girders, upper plates, and rafters and rafter layout.

Cross-section plan:Shows the guts of the foundation, the walls and ceiling, and roof. Most of the time drawn at larger scale to identify with greater detail primary structure elements that are not seen at the smaller scale.

Signatures: of plan designers and engineers required by code.

And with that you'll need engineer calculations, soil reports and permits from the varies agencies required by code and local officials. / Read on!

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Building: Site stakes & Foundation Prep

Keith Bray — Tue, 09 Mar 2010 18:40:02 +0000

The Right Tool For The Right Job

I left off the other day wanting to include some helpful informatiom about specialized tools and equipment. Because, I'm amazed, of all the technological advances abounding these days it's awesome. They literally have changed the world that we live in, especially since I was just a little kipper. (fish)

I remember when my dad wanted a new item; we would go to LOWES, HOME DEPOT or any other specialized tool suppliers; he would have a particular purchase in mind of course. Take a trowel or a fishing pole for example, I would follow him through the store and observe how he would approach the tool he wanted, he'd pick it up and examine it from all angles, put it in his hands to feel the weight and texture, and the grip for instance, checking it for perfect balance or something that had to do with the technical handling, and if he liked it and it felt right and the price was right, he bought it. You learn by experience. The new tools and equipment these days almost eliminates manual labor. Almost!

I'm going to leave this subject for now. I'll try to cover tools later in another post. Stay tuned!!

We were setting building stakes, and left off at our baseline where we had established our two front corner stakes. This was a critical step in the construction process because of it's critically to the square and level of our building; once your square and level is achieved the foundation and everything that follows is so much simpler and all phases of the project falls in place.

Batter Boards

We have our baseline and first building corners. Now lets proceed with the rest of the stake-out. To do this we have to set up batter boards. Batter boards are: horizontal boards nailed to 2X4 posts set at the corners of a proposed excavation site. They're use is to indicate the desired level, also as a fastening point for stretched strings to show the outlines of foundation walls or perimeters of your building.

We start by simply setting this temporary framework to the outside of both ends of the intended structure. Now; from the corner stakes, measure approx. 8 or 10 feet to the outside of the building. Mark this length on the baseline with an indelible ink marker. Do this at both corners.

Now; from this spot; at right angles to the baseline, on both sides of the line, measure 3 feet, and drive a 2X4 stake deep into the ground on both sides of the baseline. Then place underneath the baseline a 1X6X6 cross-member and attach ( via. nail or screw gun ) it to the 2X4 stakes. This set-up forms the frame-work to fasten your building lines. Check that the cross-member is level and the base line is centered on the 1X6. Mark the position of the string on top of the batter board, move the string to the side and make a saw kerf on top of the batter board. This is done with a hand-saw by making a slight cut through the mark, forming a groove on top of the batter board. This groove will indicate the exact location of the baseline on top of the batter board when you need to take the strings down and put them up again. Do this for both ends.

You'll need batter boards built in front of the corner stakes also. Again measuring from the front of the corner stake measure out 8 or 10 feet at a right-angles to the building line, then from there measure paralell with the baseline 3 feet on both sides from this spot and drive two 2X4 stakes deep into the ground six feet apart from each other. Then nail the 1X6X6 cross-member to the 2X4 stakes. Do the same for the other stake.

Transit

Both pairs of batter boards must be level and at the same height, to check this you'll need a transit: Automatic optical leveling unit, is an accurate leveling system. By getting the leveling bubble inside the circle a compensator does the rest. Some uses include decks, landscaping, roadwork and foundations.
The transit can be set up anywhere on the site. you use a measuring rod, that comes with the transit set. The rod is placed on top of the batter board for instance and the height is checked by viewing the rod through the transit and noting the height. The height will be the same for all the batter boards. To make adjustments raise or lower your 1X6 cross-member as needed. Every batter board maintains proper elevation of a structures, excavation and trenches or any kind of below ground work. Please read on!

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Pre-Excavation, Precaution & Considerations

Keith Bray — Mon, 08 Mar 2010 03:19:40 +0000

Before excavation you should have in progress, in place, or on site; Utilities, electricity, water, disposal site, telephone, gas, port-a-potty, Howard Johnson Catering; and underground cables and conduit lines, located marked and staked. You can get help from the utility department and the building department. Your plot plan will indicate the location of other important items and where they enter the site. As mentioned earlier, this should be accomplished at the first stages of the process and are essential to work accomplishment.

Alternatively, if your requirements include installing a septic system, drain field, water well, or dry-wells; your plot plan will show the location of these areas also. Such inclusions, are to be marked and staked also, this will prevent heavy equipment operators from moving through these areas. To accommodate heavy equipment drivers arriving to and through the site you should clearly lay out roads to traverse in and out of the area.

Plan in advance what your trenchers and graders will do, you'll want to keep them gainfully employed. The expense of just hauling equipment to the site warrants the extra planning and added forsight will streamline and expidite operations, saving in time and money calling the operators back for other digging and trenching. Also, specify in your contract where and what you want done with the excavated soil, or your load will be hauled in dump trucks, possibly to some other site (Not Yours).

The landscaping features of your site, you'll want to maintain, and should be roped off and marked that the natural surroundings will be preserved and undisturbed. You chose the site with distinguishing amities in mind that characterize the site. It's your dream location with a stunning view. Keeping it personal and impressionable in accordance with these attributes in design and selection of your location and building site.

Land developement processes are heavily determined by location and land form. The choice of location dictate the methods that will be followed and determine how the development will proceed. For instance, say you build on flatland. Some things to consider would include the natural drainage or water shed. Is there adequate drainage of the area? Is there standing water puddling on the site? Are you building on a landfill? Will you have to adjust the location of the site?

This being the case, you'll need to raise the grade, to improve drainage and fresh soil has to be compacted. The improved run off will take care of your foundation from being inundated with water. Be careful, to ensure your grading operations won't disturb or ruin the surrounding areas by water shedding to other properties. However if the natural shed is inadequate you'll have to install drainage trenches, to route the water to a storm drain, sewer, or stream.

Consideration for sites situated above the street level or on a hill would pose a different set of circumstances, especially during the rainy or winter months. The elevation of driveway and walkways could be trouble-sum and depending on the elevation, this could prove to be hazards. Such circumstances must be taken seriously and well planned out. Other thoughts; during excavation; stock pile your soil on site a safe distance from the excavation and out of the way of the construction work. You'll need the soil for filling and grading latter. Planning and saving your soil will help to keep the grading and land filling from exceeding expenses.

Where there are overhead power-lines in the area, arrangements for electricity can be made by havng a temporary post a drop and a meter installed. If overhead powerlines is undesirable, check to see if an underground power cable is available. If that's not the case, whether you want power lines hung on your house or if it's better to bury the cables underground. Underground cables will be more costly and if there is no power close by; in either situation, clearing operations may have to be performed to get power to the site. Where-as above ground power, is not as expensive and access to power provided by a temporary drop is more feasible.

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Construction Site Prep. cont...

Keith Bray — Sun, 07 Mar 2010 19:15:01 +0000

I left off looking at Site Analysis and there's more to site preparation as you will plainly see, alot that goes into site preparation is contingent on the indigenous surroundings and soil types in the chosen site, for instance; is the location located on marsh land or on a land fill, beach front, shallow water table, hills, mountainous rocky areas. All of these different land forms require a certain set of planning techniques, circumspectly before you start the land grading phase.

Questions such as these and many more are needed in determining the relationships of crafts. What they will perform and how they will accomplish it. What are the materials and equipment requirements needed to accomplish and complete the task. Carefully consider environmental factors that a site presents in order to make responsible planning decisions. These decisions take into account the indigenous surroundings but are not limited to, topography of the site, plants, trees, wind directions, the path of the sun, water drainage, to include the availability of water, electricity, dump site or landfills as part of the pre-planning stage. Keep in mind; be prepared before hand to take action in the event that some unforeseen problems may arise, be prepared, having a contingency plan in place that you can fall back on in the event something may cause you to alter certain aspects and deviations from your original plan, but being prepared is the answer to the solution and will streamline operations, if needed.

Utilities: Information concerning site utilities are found at the utilities departments and companies for the local area. They can provide you with the drawing containing the information needed. this information includes the location of all the utilities and their locations around and on the site.

Human and Cultural: This information is obtained through the census and statistics on the neighborhood. Regarding these statistics, they can be found at the municipal planning agency.
Climate: through the local weather service you can get information on conditions such as: rainfalls, snowfalls, humidity, and temperatures over the months must be considered and analyzed. the sun-path and vertical angles

throughout an entire year are important

References

List taken from: Site analysis, By: Edward T. White

Building Lines and Batterboards

Keith Bray — Sat, 06 Mar 2010 18:30:15 +0000

CORNER STAKES

For the sake of clarity, we'll call the first corner stake located on the baseline, point (A); and the second corner stake;( B). To find (C and D); refer to the site plans and note the exact depth of our structure; apply this figure by measuring from the corner stakes ( A and B ) the specified width or depth of the building, to points ( C and D ).This marks the rear structural line and is parallel with the baseline, set batter boards to this measurement using the same techniques described in setting the baseline batter boards. This set of batter-boards will hold the second line that we,re to put up to show the the exact width of our building site. After you have this pair of batter boards installed; stretch the string and tie it to the 1X6 cross-members. Cut a slight groove in the top of the cross-member where the line intersects with the frame-work. These kerfs will hold the exact width of your building line. Do the same with the adjoining frame member.

Batter Boards

Now; we have the base and rear line in place, it's good practice to make sure that the level of the batter boards is maintained throughout this process. With the transit set up in the center of your site, check and recheck the height and level of every installed batter board; the sides and the front and the two back boards and make adjustments if needed.

Let's proceed with the last two batter boards which are built 8 or 10 feet beyond the back building line facing the two front batter boards. Easy!

Baselines

At a 90 degree angle to the baseline tie a string to the front batter board at corner stack (A) and pull it down the side of your structure to the opposite end and tie it to the back facing batter board. Check with a plumb-bob, the strings cross directly over corner stake (A). Then Check your angle by using a method based on the Pythagorean theorem and that is simply; from corner stake (A) measure 3 feet across one line (A,B) and 4 feet on the other line (A,C) mark these points, then measure across the two points which should equal 5 feet. This is called the 3,4,5 method.And you can obtain greater accuracy by increasing this number by two. For example 6,8,10 can be used. Lines have to be tight!

A quicker and easier way to square the corner is to set your transit directly over point (A)drop a plumb-bob centered directly over the stake. This will center your transit exactly over point (A). Set line (A,B) to 0 degree by pointing the transit at stake (B) and aligning the transit at 0 degree to stake (A). To find (C) turn the transit while maintaining the 0 degree mark pointing to stake (B) set the transit head to 90 degrees and sight down to the base board at point (C) and mark the transit cross hair location on top of the batter board, marking the spot for your line and where it should be tied to the batter board. Tie the string at the mark and re-check your 90 degree angle.

With the angle verified and correct. Find point (D)by measuring the specified length indicated on the site plan point (C) to point (D),mark the location on the line, adjust your lines and tie it to the base board. Finally, check the diagonals of your site by measuring across the layout. Take a measurement from point (A,D) and compare that measurement to the diagonal of points (B,C)These lengths will be the same.

If everything went right with hardly no problems, your layout should be square. Go-to line intersection (A,C) drop a plumb-bob at this point and drive a 2X2 stake deep into the ground centered on the plumb-line, and place an 8 penny finish nail precisely at that spot. Do the same for the line intersection of point (B,D). And this completes the layout and the building line frame-work. Thank Goodness!!

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Excavation; Process Developement

Keith Bray — Fri, 05 Mar 2010 04:47:19 +0000

Foundation Types

The excavation process begins after considering the type of foundation, (which is the lowest division of the building) needed to support the structure. In general, the foundation is a system constructed entirely or partly underground and is composed of the supporting soil, footings, load bearing walls and support columns. The purpose of the system is to anchor and transmit the load of the structure, distributing the weight uniformly through the footings to undesturbed earth, without exceeding the bearing capacity of the soil.

With that being said, we touched on soils for this reason; the load bearing capacity of soil types that differ substantially in different parts of the region are crucial factors to considering which foundation type is appropriate for our use. Basically, foundations can be categorized into two broad groups, shallow foundations and deep foundations. Factors in selecting a foundation type include:

Typical use and Associated Loads (Est. Movable and Fixed loads)
Subsurface Groundwater
Site Topography
Building Code Requirement
Method of Construction

Shallow type foundations, cover for the most part, residential construction; and can also be used for larger high-use type facilities. For our purposes, my focus will be restricted to foundations for residential light frame construction. For anything other than a single-family dwelling unit on stable soil, a geotechnician needs to take a subsurface analysis to determine the type and size of the foundation system required.

Note: The Road Map

Your Blue Prints are compete, approved, signed off for the listed special and specific tasks to be completed. The prints will descride in depth the length, width, height and every pertinent illustration needed to fabricate, form and construct the work of each component of the project. And will be in complete compliance with engineered structural standards and plans, the layout of each phase of the construction process in it's entirety. Every detail from the foundation to the finish specification, to the minute detail work of the finished structure, and you are encourage NOT to deviate from those plans under any circumstance; without prior approval by the planner, engineer, building codes and other governing agencies. Signed off by proper authorities to make the changes to the original plans. The approved blue Prints are your only authoritative guidelines that you're to follow. Everything else is ( FOR INFORMATION ONLY. )

Shallow foundations for residential use; for now, we'll limit our discussion to the three following types:

Full Basement
Crawl Space
Slab-on-Grade

Slab-on-Grade foundation systems:

The lowest part of any shallow foundation system is the spread footing. There are several types of spread footings but the most commonly used in light-frame construction is the strip and isolated footings. The strip footing is a continuous slab footing formed to support the foundation walls and the isolated pier or column footings provide the base for individual columns, and girders which spread the weight of the superstructure over a greater surface area of undesturbed soil.

The footing for slab-on-groundfoundation, start with excavating for the form work, which is dug out and set 12 inches below the frost line. The depth of frost penetration in the soil depend on the soil type, water content of the soil and the part of the country or region that you live in. Since the climate in certain regions differ from dry to climatic the differences in footing depth for on-ground footings would vary from 1 foot in one part of the country to 5 feet in another. So the excavation can vary from just scrapping away top soil and removal of vegetation and foliage to cut out depths from 1 to 5 feet. The weather plays a huge factor in setting concrete footers, you can pour concrete only when the weather is condusive to a pour. Unless your prepared to take extensive measure to protect the concrete from cold weather. Never pour concrete when temperature falls below 40 degrees. We'll come back to this latter.

The footer width is normally twice the thickness of the foundation wall which is 8 inches. Double the dimension is 16 inches in measurement for the width of the footer. The thickness of the footer normally range from 8 to 12 inches in light frame construction. This is not engraved in stone standards, but minimum guidelines do apply for pouring footers, and are based on a single family unit. Refer to your blue prints for exact specifications. For two story units the footers will most likely be deeper and wider contingent upon the facts of groundwater, soil type, and climate.

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Site: Grade, Layout & Building Stakes

Keith Bray — Thu, 04 Mar 2010 19:00:28 +0000

Once you have completed your site survey, the site is cleared of trees, brush, depending on the grade of your parcel, fill dirt has to be brought in or taken away. Also, take note on the site plan, the necessary locations of utilities, electricity, and water. And do you have a proper disposal site in place or do you know of one in the area.

What's Next! Do you want to grade before you stake or stake before you grade or stake while you grade or is that really up to you? Do you know the answer? I've been on sites were multiple operations were all performed simultaneously and it was quite hazardous, you would not have wanted to be there, and I would not have recommended it. Is their a clear definitive answer to this question, should we take a pole, if we stood around all day for a show of hands we wouldn't get much done would we. Our next step is to establish our perimeter lines. This is the logical step. You wouldn't know where to start your grade operations without establishing where to begin leveling the ground for your foundation anyway, Consequently there is some leveling that is necessary before you finish grade. This is just skimming, clearing, and smoothing out the surface, then, lets get the stakes out.

So we establish our boundaries, starting with our property lines. This critical step is usually done by a licensed surveyor will insure an accurate layout of the baseline. Let's proceed to the setback dimensions given on the site plan. Starting from one end of the property line, take the measurement from the site plan and measure the distance of the setback from the property line to the location of the baseline and drive a 2"x2" stake into the ground at this point. This marks one end of your baseline. Go to the other end and do the same. You'll have the same measurement for both ends of the property line to the baseline.

Tie construction string to one of the stake you just placed and pull the string parallel to the property line; the amount of string needed to reach to the other stake and tied. This string should be tight. Now you have a baseline for the proposed site. Illustrated on the site plan is a previously set or established land mark, which is used to pin-point the first corner stake of the building. Measurements shown on the site plan, are taken from that marker to a location on the baseline that indicate our first building corner stake.

Measure and mark this point on the string with an indelible ink marker. This is the exact location of the first corner of the building. Drive a 2"x2" stake deep into the ground at this spot, just below and centered on the mark of the string. Use a plumb-bob, and drop it to the top of the stake, perpendicular to the mark on the string. Next, mark the position of the plumb-bob on the top of the stake. Nail an 10 penny finish nail, where you marked the top of the stake and drive it into the top of the stake, designating the exact location of the corner.

Once you have this location established, your ready to proceed with the rest of the building stakes. Now, measure the length of the building, starting from the first corner mark located on the building line, measure the specific length listed on the site plan and mark that point on the building line for your second corner stake. Drive the stake into the ground, centering the stake below the mark as you did with the first stake, using the plumb-bob etc.

All your building stakes will be installed in a similar fashion and we will consider the rest of the layout next time for the rest of the story.

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Soils Types & Characteristic

Keith Bray — Wed, 03 Mar 2010 02:12:42 +0000

What's The Big Deal About Dirt?

I decided to take a pause for the cause; and talk a bit on the topic of soil. This is where it all begins, and is literally the base; foundation for the foundation; and ground for the most important of all topics. It is the lead player of the critical roll in construction. If it goes wrong here or fails, the whole system falls; literally falls; or debilitates the whole structure on which the whole framework stands. For this reason, lets take a moment to look at soil profile and characteristics, and ponder the intrinsic aspects of the subject, and search the reasons why it could be detrimental to disregard basic standard procedures and to neglect the proper steps that must be applied.

First and foremost, the foundation of the house, and the ground on which it stands; properly understood with accurate engineering principles applied, bears it's own weight in gold. The study of soil, is worth the time to recognize certain natural characteristics, how it reacts under stress and responds to determined loads, a science all by itself. Interesting!

Load bearing capacity of soil varies according to it's composition and water content, the higher ratio of water to soil degrades it's capacity to bear heavy loads. You would see this if you watch a work site with equipment drivers working the site. On a dry day there is no problems, but after a rain you'll observe the tracks of the heavy equipment sink into the ground and mush out from between the tire treads. The same principle applies.

Soil is made of large or small particles derived from one or more minerals that make up solid rock and the various types are determined by the size of it's particles.

Rock Classification

Group: Igneous (Intrusive)

Characteristics

Granite; mostly quartz and potassium feldspar with mica, pyroxene, and amphibole

Environment: Deep-seated, coarse-grained pluton

Syenite; mostly potassium feldspar with mica, pyroene, and amphibole

Environment: Deep-seated, medium grained pluton

Monzonite; plagioclase and potassium feldspar with mica, pyroxene, and amphibole

Environment: Deep-seated, course-grained pluton

Diorite; mostly plagioclase and quartz with abundant mica, pyroxene, and amphibole

Environment: Deep-seated, course-grained pluton

Gabbro; equal amounts of plagioclase and mica, pyroxene, and amphibole

Enviornment: Intermediate-depth, medium- to coarse-grained pluton

Peridotite; mostly olivine, pyroxene, and amphibole with little plagioclase

Environment: Very-deep-seated medium- to fine-grained pluton

Group: Igneous (Extrusive)

Characteristics

Rhyolite; mostly quartz and potassium feldspar with mica, pyroxene, and amphibole

Environment: Fine-grained fissure or volcanic eruption

Andesite; mostly plagioclase and quartz with abundant mica, proxene, and amphibole

Enviornment: Fine-grained fissure or volcanic eruption

Basalt; equal amounts of plagioclase and mica, pyroxene, and amphibole

Enviornment: Fine-grained fissure or volcanic eruption

Group: Metamorphic ( Foliated )

Classification

Gneiss; mostly quartz and feldspar with mica, and amphibole

Environment: Course-grained, deep-seated

Schist; mostly mica and platy minerals with less quartz and feldspar

Environment: Course-grained, deep-seated

Phyllite; micaceous rock intermediate between schist and slate

Enviornment: Medium-grained, moderate depth

Slate; feldspar, quartz, and micaceous minerals

Enviornment: Fine-grained, moderate-depth

Group: Metamorphic ( Nonfoliated )

Classification

Hornfels; metamorphic clay materials

Environment: Contact with hot magma bodies

Marble; metamorphic carbonates

Environment: Course-grained, deep-seated

Quartzite; metamorphic sandstone

Environment: Fine-grained, deep-seated

Group: Sedimentary ( Clastic )

Classification

Conglomerate; fragments of rounded gravel-sized sediments

Environment: River and glacial deposits

Breccia; fragments of angular gravel-size sediments

Environment: River and volcanic deposits

Sandstone; coarse-grained quartz and feldspar with minor accessory minerals

Environment: Marine and river deposits

Siltstone; fine-grained quartz and feldspar with minor accessory minerals

Environment: Marine, lake, and river deposits

Shale; very-fine-grained sediments, mostly feldspar

Environment: Marine and lake deposits

Group: Sedimentary ( Nonclastic )

Classification

Limestone; calcium carbonate, often with skeletal fragments

Environment: Marine and lake deposits

Dolomite; calcium magnesium carbonate

Environment: Marine deposits and veins

Gypsum; hydrous calcium sulfate

Environment: Near-shore brine pools

Chalcedony; microscopic silica

Environment: Deep marine and groundwater

Soil types, as determined by particle size

Cobbles and boulders: larger than 3 inches in diameter.
Gravel: smaller than 3 inches and larger than number 4 seize ( approximately 1/4 inch ).
Sand: particles smaller than number 4 seize and larger than 200 seize ( 40,000 openings per square inch ).
Silts: particles smaller than 0.02 millimeters (mm) and larger than 0.002 mm in diameter.
Clay: particles smaller than 0.002 mm in diameter.

Having lived in New Mexico where the ground is very hard and dry, subject to flash-flooding. The soil bears looking at and to make a point, you don't have to go far in the desert to find sinkholes in the ground. These are areas in the soil where water streams flow underneath the soil and washes the lower layers of soil away from underneath and after a short time it caves in.

These cave-ins serve to point out the fact that a thorough surface and subsurface investigation should be performed to establish criteria for the foundation requirements of the proposed structure.

Please leave a comment let me know what you think.

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Soil Investigation

Keith Bray — Tue, 02 Mar 2010 20:01:02 +0000

Soil And Foundation

A surface and subsurface investigation looks at a number of factors that include but is not limited to, water drainage, water tables, topography, soil types and characteristics, and other laboratory test that are required to ascertain the fitness and suitability of the soil for support of the proposed structural.

We made mention of some of these topics earlier, but we should dig a little deeper to uncover some of the hidden effects that take place under different loads and stresses with different soil types; for example; gravel to clay mixtures or silty soils with a high sand or clay mixtures, and how it reacts when these stresses and loads are applied.

Classification and Description

Soils consist of grains; rock fragments and clay particles, with water and gas, either air or condensation, these particles are trapped in the void spaces between the grains. A soil classification scheme is used to separate soils into broad groups each with broad similiar type and behaviour.

The different classification schemes fall under, agricultural: based on how soil supports crops. Geological: based on the age of the deposit or nature of grain. Civil Engineering: based on mechanical behaviour of the soil and many others. The subject of soil is vast in scope and for our purposes we don't need to go into all the technical aspects and breakdown sciences. but we will investigate some basic areas and facts about soil that is of interest and specific to what we, in our endeavors, will lead toward accomplishing our goal.

Soil description is essentially a catalogue of what soil is and describe the soils features. There are several of these schemes available; published in the National Standard, and to some extent reflect the characteristics of most common soils in the region. Consult the relevant standard for the region where you work.

For a concise and in-depth study of soil you can go to or consult:

The United States Department of Agriculture, (USDA). Natural Resources Conservation Services, (NRCS) website.
For Engineering; the Unified Soil Classification System (USCS)
Soil Mechanics; By R.F. CRAIG
Geo-technical Materials in Construction; By Marion P. Rollings, P.E. and Raymond S. Rollings, Jr., P.E.
The Mechanics of Soils and Foundations; By John Atkinson

External loads and water pressure interact with each other to produce a stress that is effective in controlling soil behaviour and as external loads are applied, compression of soil volume occurs and the grains rearrange themselves and the void spaces change from compaction.

Soil shearing is basically frictional so that strength increases with normal stress, and with depth in the ground. Soil stiffness also increases with normal stress and depth. Combining these basic features of soil behaviour leads to the observation that soil strength and stiffness decrease with increasing water pressure and with increasing water content.

Soil compression and distortion are generally not fully recoverable on unloading, so soil is essentially inelastic. This is a consequence of the mechanics of compression by rearrangement of the grains; they do not un-rearrange on unloading.

Please leave a comment let me know what you think.

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Footings and Excavations

Keith Bray — Mon, 01 Mar 2010 07:53:15 +0000

Shallow Foundation

Footings

The size and dimension of the footer are based on soil characteristics. Soil and subsoil in their natural state are often sufficiently stable to support light frame construction, the average load bearing capacity for undisturbed soil is 2000 pounds or greater, per square foot. Where building code permit;today modern home builders, in light frame construction build houses using a form type called Earth-forms, simply on an excavated surface, cleared of vegetation, foliage, etc. A trench is dug out according to the footer specifications, say for example the frost-line is at one foot, so you know the footer dimension for a 8 inches thick wall is going to be 16 inches wide by 8 or 12 inches deep, dependant upon soil characteristics, but 8 inches deep is standard thickness, I've heard of 6 inch footers this might be ok for a garage pour but I would never use anything less and neither should you or you'll be asking for trouble. Refer to the blue prints.

Your trench depth would be 1 foot for frost-lineplus 8 or 12 inches for the footer, so your trench depth would be 32 or 36 inches. That's 8 or 12 inches for the footer 12 inches below the frost-line plus one foot of soil to the surface, or grade, so our trench would be 32 to 36 inches at the the highest point of the natural grade.

Then your trencher will dig your earth-form 32 to 36 inches deep by 16 inches wide or more and keep a level dig to complete the earth-form.

From the blue prints the height of your batter board represent the top of the finished foundation wall. If we use the example above it would take two courses of cement block to bring the foundation wall to grade and another two to three courses to the building lines or finished foundation wall. Your underground utilities are marked, staked and stubbed your trench dig will come within two feet of the underground and stubbed utility line and since most of these are buried including the telephone and television cables as well contact with a company representative will alleviate the problem of accidental damage to these lines. The rest will be hand dug to prevent damage by heavy equipment.

Excavations

Some builder's like to put in temporary batter-boards and stake the approximate location of the excavation so the backhoe or bulldozer operator can perform the dig before the exact building lines are set. This is an extra step to the process but it eases the burden from the equipment operator by giving him latitude in movement and should result in greater precision.

Then go back and set the exact location for the building, it's a matter of what is expedient at the time, however, the lines have to be taken down before this operation. Once the lines are down the digger can start digging. Make sure the soil is piled a good distance from the excavation, when you go back to hang your lines, dirt piles won't have to be hand shoveled away from the path of the lines. The operator will dig approximately two-feet or more beyond the building perimeter to allow for pipes, drainage and work space. On a clay or cohesive type soil you'll need slight fer-ring back depending on the depth of the dig and on loose or sandy soil types, you'll cut the slope back at a 45 degree angle to prevent cave-ins.

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Earth and Water

Keith Bray — Sun, 28 Feb 2010 03:06:09 +0000

How Deep to Dig / Striking Water

Previously our discussion was briefly based on elasticity, stress, saturation and unsaturated soil, and effects of the soil when loading and unloading occurs. Our goal is to provide a solid base for our footings and foundation walls.

Clayey type soil and the behaviours associated with it when combined with water. We stated; this type looses strength when the water to soil ratio is increased. Normally when the foundation is dug, the deeper we dig the harder the soil will be from natural compaction, the deeper the depth the denser the soil, the tighter the compaction, the smaller the void spaces in the soil.

A problem may exist, when builders put up a structure. They usually don't consider soil as much in light frame construction, because soil in it's natural state, under normal circumstances, will support the single family unit. As a matter of fact; some location through-out the country, building codes allow the builder to place footers without using reinforcing steel rod, that add strength also increase the tensile strength of the footer, allowing added resistance to upheavel that occurs in frozen soil.

Not to worry, these questions and more, concerning soil and the structure are properly addressed by soil engineers and planners, at the planning and drafting stages.

For example:

Do foundation loads match loadings assumed by soils engineer?
Have earth pressure, including effect of surcharges and sloping fill, been included in the design?
Has correct assumption of use of active or passive forces been applied?
Do all wall elements have adequate resistance through friction, cohesion or passive pressures?
Have hydrostatic forces been applied to the wall, or have adequate steps been taken to remove pressure?
Was weight of soil slabs and superimposed loads included in the design of the footings?
Are elevations of foundation consistent with recommendations in the soil reports?
Has foundation settlement or heave been addressed in the design?
Have horizontal forces, applied to deep foundations, been adequately addressed?
Does pile spacing match requirements for soils report and pile cap design?
Has settlement of large fills, adjacent to rigid members, been assessed?
Can both downward and upward loads be transmitted from pile cap to piles?

So, engineers keep an extensive report, design and soil studies, before we start the build.

Safety factors are stressed with the depth of the dig and the soil type, the sandy soil types will likely need reinforced shoring if the dig is over three or four feet. the backing will prevent caving's protecting workers.

Water Table

In the B horizon, which is the depth of earth just below the A horizon which is normally one inch to three feet deep, and composed mainly of top soil. The lower the water content the greater the load bearing strength, now where the water table is concerned, depending on the area and the region of the country. The water table is the depth at which the soil is completely and permanently saturated. This information is available from building inspectors, or the building department etc. This is good to know. For example say you find the water table is at 18 feet and your basement is 8 feet, the water table will be approximately 10 feet below your basement. With this in mind, if your basement is wet you'll instinctively know that the problem is not a water table problem, but a natural drainage or runn-off. And you'll need to look through other avenues to find the problem. Gutters for example may be broken, downspouts missing or the drainage from the building not adequate or it could be a water-proofing situation, or even, drainage into the soil from a broken or damaged water line from a construction site or city repair.

If in the B horizon the type of soil is a clay type there may exist a hard pan where there is low water seepage and you have a greater surface saturation of water unable to penetrate below the high dense clay level the A horizon soils ( top soil ) is normally saturated and will not take on or soak any further. Therefore allowing water to stand at higher levels during in-climate weather or the winter months when snow is on the ground. Again this is due to improper drainage and needs attention to correct this problem.

Please leave a comment let me know what you think. Have a good day!!

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Regress To Safety Then Forward

Keith Bray — Sat, 27 Feb 2010 00:04:06 +0000

SAFETY

A ConstructionTopic Recap

Safety: to re-iterrate; it is of paramount importance, so I wanted to take a short break to say a word from the National Institute for Occupational Safety and Health (NIOSH). According to NIOSH 21% of fatalities, the largest number of workplace fatalities reported for any of the industry sectors.

Construction is targeted by NIOSH through the National Occupational Research Agenda (NORA). They identify causes of and develop programs to prevent injuries and fatalities in construction.

Just to name a few safety topics we need to look at:

Asphalt: Occupational Exposure, PPE
Carbon Monoxide: Poisoning in soil and confined spaces, PPE
Drywall:Back problem and lifting techniques, PPE
Electrocution:Electrical safety and precautions, Power lines, PPE
Ergonomics: Stress reduction and repetitive motion, PPE
Excavation:Caving's, precautions
Falls: Roofs, ladders, floors, etc
Lead Poisoning: Blood lead levels in construction workers
Nail Guns: Self Explanatory
Silicosis: What is it and what are the symptoms
Skid Steer Loader: Equipment operation and associate dangers
Fumes and Illnesses:
Musculoskeletal Disorders

See the full range of NIOSH publications on a variety of reported safety issues, injuries and fatalities.

Go to the NIOSH Construction Topic website for more.

A Note to Readers

I don't like to tell on myself much but at other times you can't help it. Every place I went in the military, somehow, I was shop tools and safety monitor and I enjoyed the position it looked good for annual performance reporting. Ordering all tools for the carpentry, masonry, welding, and the SMART team which was the Structural Maintenance and Repair Team (reoccurring maintenance), and the Heavy Construction Shop, for large projects, some up to a million dollars in cost. All this was an enlightening experience. Most shops I had the honor to run and operate.

But I said that to say; I have the experience but I'm a little older and want to move to other things like building inspector or something like that. Which I'll probably still try to do.

But Internet savvy I'm not. And I wish I knew someone that I could turn to for answers, but at this time I don't so, I ask you to bear with me as I stumble on publish these post on my own, as I go my hope is to become better. Because I'm trying to learn and write at the same time, It's real difficult to keep up, but it's a comfort for me to do this. Like I alluded to in my about me page, I really don't like wasting too much time watching T.V. as entertaining as it is. I have Warner Cable with a lot of channels.

I said this for the readers of this site, that It has been of a great encouragement to me to hear from you to keep it up, and just for those whom I hope, I've been of some help to. I was refreshed to know that all my efforts were not entirely in vain, and to again thank you for visiting this site.

If I can be of some assistance, even for that one person. I would do my best!

Keith

*Please leave a comment or let me know what you think.

STAY TUNED FOR MORE TO COME!!!!

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Graded Soils / And What ???

Keith Bray — Fri, 26 Feb 2010 05:26:28 +0000

I decided to take a minute to gather my thoughts and read some of your coments as to get a feel for what you need and how I might better assist in these matters of construction. The field is huge, it's hard to say. So leave a clue, that I might work with.

Help Me to Help You!!!!

And I purpose to stop jumping around so much, you know it's easy to get off the subject, and on to a subject utterly unrelated, you just can't help it. And I'm not trying to make excuses it's just a fact, when your full and running over with ??( WELL FORGET IT ) you loose control.

Ok I want to close on soil, but I can't just yet!

When the soil sample is taken, it will consist of a mixture of every type and composition of the soil ie, it will be composed of gravel, sand, silt, and clay. And it is described by the most predominate part, ie. Is it predominately gravel, sand, silt, or clay. So it's description references the mixture with the most prevalent part; by saying the soil is a gravelly sand, it means, sand mixed with gravel, or a silty sand would be a sand mixed with silt or clayey sand, that is sand mixed with clay.

These classification of soils are critical for engineers to be able to identify problem soils.

Classifications of soils developed by the American Society for Testing and Materials (ASTM) standards are D 2487 and D 2488. And the Unified Soil Classification System ( USCS ) are used to describe the grain size of a soil.

ASTM Terminology

Coarse-Grained Soils More than 50% retained on a 0.075 mm(#200) sieve.
Fine-Grained Soils 50% or more passes a 0.075 mm (#200) sieve.
Gravel Material passing a 75 mm (3 inch) sieve and retained on a 4.75 mm (#4) sieve.
Coarse Gravel Material passing a 75 mm (3 inch) sieve and retained on a 19.0 mm (3/4 inch) sieve.
Fine Gravel Material passing a 19.0 mm (3/4 inch) sieve and retained on a 4.75 mm (#4) sieve.
Sand Material passing a 4.75 mm sieve (#4) and retained on a 0.075 mm (#200) sieve.
Coarse Sand Material passing a 4.75 mm sieve (#4) and retained on a 2.00 mm (#10) sieve.
Medium Sand Material passing a 2.00 mm sieve (#10) and retained on a 0.475 mm (#40) sieve.
Fine Sand Material passing a 0.475 mm (#40) sieve and retained on a 0.075 mm (#200) sieve.
Clay Material passing a 0.075 mm (#200) sieve that exhibits plasticity, and strength when dry.
Silt Material passing a 0.075 mm (#200) sieve that is non-plastic, and has little strength when dry.
Peat Soil of vegetable matter.

Letter Definition:

(G) Gravel, (S) Sand, (M) Silt, (C) Clay, (O) Organic

(P) Poorly graded-uniform particle sizes. (W)Well graded diversified particle sizes. (H) High plasticity. (L) Low plasticity.

This is the soils classification systems most used in construction, engineering, and geology. It broadly breaks down soils to these two classifications (1) Granular: ( Coarse- grained soils more than 50% of coarse fractions retained on a #200 sieve. )

This granular group symbols are "GW": Well-graded gravels and gravel-sand mixtures, with 5% fines or no fines, and are gravels that, 50% or more of course fractions are retained on a #4 sieve, called Clean gravels. "GP": Poorly-graded gravels and gravel-sand mixtures with 5% fines or no fines. Then there are Gravel with 5 to 15% fines, and this group GM; Silty gravels, gravel-sand-silt mixtures. And "GC";Clayey gravels, gravel-sand-clay mixtures. "GW-GM"; Well-graded gravel with silt. "GW-GC"; Well-graded gravel with clay. "GP-GM"; Poorly-graded gravel with silt. "GP-GC"; Poorly-graded gravel with clay.

Fines are defined by the American Association of State Highway and Transportation Officials ( AASHTO M 147 ) as natural or crushed sand passing the #10 sieve and mineral particles passing the #200 sieve.

Don't forget to drop me a note!!

Thanks in advance.

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Granular Soil Uses

Keith Bray — Thu, 25 Feb 2010 03:43:17 +0000

THAT'S GOOD DIRT

Alrighty Then; We were discussing granular graded soils, and we ended with a brief look at classification charts (schemes); ASTM, USCS, and the AAHTO and ( a lot of other acronyms we haven't looked at ), said these standards are used by our engineers in determining soil types.

We also mentioned, that soils are in combinations of each other with diverse compositions and varying consistencies. The granular soils are for the most part non-plastic, meaning; no bonding agent or attraction of particles, and no shear strength if unconfined; the particles don't sticktogether that well but, are preferred in construction use, over the cohesive (clay) types, and that's because of their distinctive characteristic like; stability, excellent drainage capability, low frost heave, best back-fill potential, dense, coarse-grained, and resistance to foundation settlement, and typical high bearing capacity. Building codes often list maximum bearing capacities for soils of general classes that may be used without soil testing in light frame construction. But these are generic and may lead to erroneous conclusions regarding the true load-carrying capability of the soil at a specific site, and so these should be used with caution.

Presumptive Bearing Values of Foundation Materials

Class of materials Bearing Pressure lb./sq.ft.

Crystalline bedrock 12,000
Sedimentary rock 6,000
Sandy gravel or gravel 5,000
Sand, silty sand, clayey sand, silty gravel, clayey gravel 3,000
Clay, sandy clay, silty clay, clayey silt 2,000

No Problem Construction Soil

Soils that are dense, coarse-grained, and properly drained. Cause very few problems in light buildings for slab-on-grade foundations.

The soils here have excellent bearing capacity, and they are not subject to significant volumetric change (we will see this later). Gravels, occur in a dense state and not likely to settle, or prone to pose that problem. The settlement that does occur is very sudden and happens immediately when the load is applied.

During trenching and grading operations, other precautions need to be heeded, ie; the natural confinement of the soil should not be disturbed, (except when compacting);, because further disturbance of the soil bed would necessitate measures that half to be taken to increase the necessary lateral support, ie; (earth retention systems; soil stabilization systems; water and Portland Cement for bonding).

Lateral displacement, is horizontal movement of soil, displaced by compression of heavy loads or the foundation. Generally this is not a problem in light frame construction. Lateral displacement is more likely to occur under heavy building loads and this problem is addressed in the foundation design. At any rate, the bearing soil must be undisturbed and stable.

Soils acceptable for use in the construction of fills, back-fills, and embankments for commercial, institutional, and industrial buildings and for large multifamily housing projects are generally limited to those in the GP, GM, GC, SP, and SC categories.

General back-filling outside of the structures is generally limited to those soil classified as GP, GM, GC, SP, and SM. However, in certain situations, some other classifications may be permitted, but that decision should be left to a competent soil engineer, and in all circumstances additional liquid limit and plastic limit requirements will apply.

Gravel and sands; The shear strength of these soils depend solely upon the internal friction between grains. Generally speaking, bearing strength is high and foundation failure is relatively infrequent. The sudden settlement that does occur takes place immediately upon application of the load and does not materially effect the foundation. The shear strength increases as the grain size increases and a well graded soil is best.

They do not hold water at all, with the exception of some sands and silts, which do exhibit a weak tendency to bond together with a negative water charge, but will easily collapse. You'll notice this while excavating in a sandy soil type; the sides will hold for some time and then start dropping off as the soil becomes unsaturated and then falls apart or collapses. It is very permeable and excellent material to use for drainage.

Don't forget to comment.

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Problem Soils

Keith Bray — Wed, 24 Feb 2010 06:10:50 +0000

Cohesive (Clay) Soils

Earlier, we made mention of clay soils, but at that time we made no effort to say much about it, so now lets cover some important aspects about this topic, and see what we can glean or derive from these interesting facts.

Like granular soils; clayey soils (Cohesive) are also, from combinations of various soil particles that range in size and shape from fine-grained to very-fine-grained, some of these clay particles cannot even be seen under a low-powered microscope.Cohesive soils are held together by a binding force called cohesion.

Under the classification system devised by the American Society for Testing and Materials (ASTM) describe this second group, Cohesive soils as follows;

Cohesive: (Fine-grained soils 50% or more passes the 0.075 mm #200 sieve.)

The cohesive group symbols Silts and Clays Liquid Limit 50% or less are:

"ML"; Inorganic silts, very fine sands, rock flour, silty or clayey fine sands
"CL"; Inorganic clays of low to medium plasticity, gravely/sandy/silty/lean clays
"OL"; Organic clays of medium to high plasticity

The cohesive group symbols Silts and Clays Liquid Limit greater than 50%:

"MH";Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts
"CH"; Inorganic clays or high plasticity, fat clays
"OH"; Organic clays of medium to high plasticity
Peat: Highly Organic Soils; "PT"; Peat, muck, and other highly organic soils

I felt it necessary to go the extra mile, and also decided that we had to cover clay soil at some length to get some since of the need to understand why they are termed " Problem Soils or Expansive Soils",and why stress is placed so heavily concerning this topic. We have to better understand the natural tendencies of clay soil due to the fact that they directly affect stability. This stability, with respect to foundation support, is of utmost importance and what precautionary steps we should take to alleviate or counter the reactions that are associated with this soil type.

Clayey soil, termed problem soils, are said to be not suitable forengineering needs. What's the reason for all the controversy? The reasons are, these soils are the main culprit to so much foundation trouble, seeing that the stability of these clays is directly affected by natural occurrence (climate). They become plastic and elongate under stress, impervious, poor drainage, high susceptibility to frost action, and low bearing capacity. And the major problem with clay soils, is a characteristic behavior that is common to clay soils and that is; these clays contain mineral constituents that as variations in natural ambientconditions (heat, rain, wind, and conditions that result from water leaks in the sub-soils) cause these minerals to swell with higher moisture content and contract in areas of widely variant moisture, and this problem is compounded by an interaction of these climatic changes.

This swelling is directly attributed to a mineral,montmorillonite orsmectite present in the soil and changes or swells with moisture content. Montmorillonite when taken from a dehydrated state to a saturated state has the capacity to free swell up to 20 fold. So a confined clay for example under a foundation or concrete pad; these clays could conceiveably exert pressures up to several tons per square foot, and that; my friend, is

the reason that foundation repairs exceed or equal to the cost of damages due to natural disasters. The last I read was 2 billion.

Let me know what you think. Have a good day!!

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Soil Stability

Keith Bray — Tue, 23 Feb 2010 20:47:51 +0000

What Kind of Dirt Is That??

I'm going a little off track, but not far. I wanted to talk some on sands because we haven't covered that yet and also, I'm not quite through with clays, so the USCS will have to suffice for the moment and then back to expansive clays. (I did give you a heads up)

For an in-depth coverage, let us look again at the chart of the Unified Soil Classification System Symbols. Broken down into four groups, and rated excellent to poor; we have:

Group I (Excellent)

GW

Well-graded-gravels, gravel-sand mixtures, little or no fines.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 8000.
Drainage Characteristics: Good.
Frost heave potential: Low.
Volume change potential: Low.

GP

Poorly-graded-gravels, or gravel-sand mixtures, little or no fines.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 8000.
Drainage Characteristics: Good.
Frost heave potential: Low.
Volume change potential: Low.

SW

Well-graded-sands, gravelly-sands, little or no fines.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 6000.
Drainage Characteristics: Good.
Frost heave potential: Low.
Volume change potential: Low.

SP

Poorly-graded-sands or gravelly-sands, little or no fines.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 5000.
Drainage Characteristics: Good.
Frost heave potential: Low.
Volume change potential: Low.

GM

Silty-gravels, gravel-sand-silt mixtures.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 4000.
Drainage Characteristics: Good.
Frost heave potential: Medium.
Volume change potential: Low.

SM

Silty-sand, sand-silt mixtures.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 4000.
Drainage Characteristics: Good.
Frost heave potential: Medium.
Volume change potential: Low.

Group II (Fair to Good)

GC

Clayey-gravels, gravel-sand-clay mixtures.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 4000.
Drainage Characteristics: Good.
Frost heave potential: Medium.
Volume change potential: Medium.

SC

Clayey-sands, sand-clay mixtures.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 4000.
Drainage Characteristics: Medium.
Frost heave potential: Medium.
Volume change potential: Low.

ML

Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts with slight plasticity.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 2000.
Drainage Characteristics: Medium.
Frost heave potential: High.
Volume change potential: Low.

CL

Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 2000.
Drainage Characteristics: Medium.
Frost heave potential: Medium.
Volume change potential: Medium.

Group III (Poor)

CH

Inorganic clays of high plasticity, fat clays.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 2000.
Drainage Characteristics: Poor.
Frost heave potential: Medium.
Volume change potential: High.

MH

Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 2000.
Drainage Characteristics: Poor.
Frost heave potential: High.
Volume change potential: High.

Group IV (Unsatisfactory)

OL

Organic silts and organic silty clays of low plasticity.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: 400.
Drainage Characteristics: Poor.
Frost heave potential: Medium.
Volume change potential: Medium.

OH

Organic clays of medium to high plasticity, organic silts.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: -0-.
Drainage Characteristics: Unsatisfactory.
Frost heave potential: Medium.
Volume change potential: High.

Pt

Peat and other highly organic soils.
Allowable bearing capacity in pounds per square foot with medium compaction or stiffness: -0-.
Drainage Characteristics: Unsatisfactory.
Frost heave potential: Medium.
Volume change potential: High.

As you well know, the gravel is key in the drainage system. It provides an unobstructed path for the water to flow away from the foundation or into a sump in a full-basement. The gravel will, further more, help to prevent pressures from building up against the foundation and curtail deflection.

Comment let me know what you think. Have a goo day!

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Clays

Keith Bray — Mon, 22 Feb 2010 01:44:53 +0000

CLAYS: GOOD STUFFF OR BAD STUFF / FYI

I'm going to get off clays and expansive soils so we can move on to getting the slab-on-grade down, or if you like the foundation walls,so we can get above ground. Not to linger; lets finish with soils after this post or the next post, I hope; and we'll come back ( I'm going to have a lot of coming back to do) and because, you don't really need to worry yourself about this stuff. It's FYI.

(But that's not the reason I want to move on, I'm getting ance. I want to go. And I want to be there at the same time. Maybe I should settle down).

Soils are all covered by the experts and in your site survey or (field exploration) all this is listed for you by an competent site surveyor and engineer. His job ( and I'm going to list several task that are accomplished here) is to obtain the following:

Knowledge of the general topography of the site as it affects foundation design and construction. e.g., surface configuration, adjacent properties, the presence of water sources, ponds, hedges, trees, rock outcrops, etc., and the available access for construction vehicles and materials.
The location of buried utilities such as electric power and telephone cables, water mains, and sewers.
The general geology of the area, with particular references to the main geologic formations underlying the site and the possibility of subsidence from mineral extracting or other causes.
The previous history and the use of the site, including information on any defects or failures of existing or former buildings attributable to foundation conditions.
Any special features such as possibility of earth quakes or climate factors such as flooding, seasonal swelling and shrinkage,permafrost, and soil erosion.
The availability and quality of local construction materials such as concrete aggregates, building and road stone, and water for construction purposes.
For maritime or river structures, information on tidal ranges and river levels, velocity of tidal and river currents, and other hydro-graphic and meteorological data.
A detailed record of the soil and rock strata and (groundwater) conditions within the zones affected by foundation bearing pressures and construction operations, or of any deeper strata affecting the site condition in any way.
Result of laboratory test on soil and rock samples appropriate to the particular foundation design or construction problems.
Results of chemical analysis on soil or groundwater to determine possible deleterious effects of foundation structures.

OK; Clay particles are made up of the finest dirt particles there is. Usually ranging smaller than 1 / 10,000 of an inch in diameter, the peculiar properties that these clays exhibit pose a serious challenge for engineers to rectify, or better; defuse the situation that these clays create.

These soils are a natural impediment to the stability of the foundation and since most residential slab foundations with their transmitted load are designed to be supported by essentially 100% of their total area,as mentioned in the previous post swell-able clays are the contributing factor that cause upheaval or deflection; (a condition exhibiting sufficient deflection from the original construction so to require remedial attention), and the loss of support due to shrinkage can and will result in settlement.

Normal settlement of fill is often active for periods up to 10 years, it is thought to be dependant upon the cycles of precipitation and drought. However it may be possible to nullify soil shrinkage by the introduction of water. Proper moisture controls;effective grade, adequate watering, and sufficient ventilation are all forms of proper moisture control and have been proven to have a successful stabilizing effect.

Keep in mind, sources of unusual amounts of water under a foundation are accumulative and because the foundation covers (protects) this area of bearing soil. Moisture seeping into this confined space via, (broken drain line under the pad, no matter the source), tends to be detrimental. Unusual water might be attributed to subsurface aquifers ( e.g., temporary perched groundwater), surface water (poor drainage), or domestic water (leaks or improper watering) and ponding could also result from a damaged water main.

The mineral montmorillonite is relatively abundant in certain parts of the state. Concerning these areas that are most affected, they are; (Wyoming, Colorado, California, North Dakota, South Dakota, Texas, Alabama, Montana, and Mississippi). These states are affected too, but not as bad; (Utah, Louisiana, Arizona, Florida, Tennessee, Oregon, Washington, and Nebraska). Other clays such as illite, attapulgite, and kaolinite also show swell potential but to a lesser extent.

Movement of soils is often precipitated or exacerbated by the intrusion of water into the soil to the extent that both cohesion and structural strength are threatened or destroyed. California mudslides are a prime example though extreme. Something to think about.

Love to here from you.

Thanks for the comments. Have a good day!!

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Basic Construction? / Investigations

Keith Bray — Sun, 21 Feb 2010 23:18:00 +0000

What is basic construction, and what is the meaning? That might have been the question for the first post. But keep in mind, safety trumps. You answer this question. To me; " Now that I think about it", there is no such thing, as "Basic Construction". What do you think?

Oh. You can throw a house up; dig a trench, pour the pad, anchor sole plates, throw up stud wall, put the rafterson, Sheath it, sheath the outside walls, do your wiring and plumbing, insulate , install outlet boxes, pull your wires, rock the walls, install utility closet and make connections, rolled felt and shingle the roof, install the doors and windows, brick, block, and flue the chimney, brick the front, place siding on the sides and rear, install the sills, weatherstrip, close the eaves, tile the floor, install plumbing fixtures, put in lights, switches, outlets, cover plates, install kitchen cabinets, counters, sinks, bathtub, Spackle and paint, pour steps and side walks, clean up your mess, look around, ask yourself," did I leave anything out"? "No", Pat yourself on the back, walk out and close the front door, brush the dust off your shoulders, pop your shirt collar, and BAM !! There it is. Then; walk off into the sunset.

The Need for Investigation

For single-family homes and other small construction, a preliminary investigation is made to determine the sites suitability for the proposed structure, and is of prime importance to designers in their information gathering for the design stages of building the foundation, from this information, you should gain the necessary facts, details, and results, about the nature and origin of the existing soils. This initial investigation will verify, if there are other needs (cost is always a factor here) and to what extent, of further investigation or; no further needs necessary, "which is the correct answer".

In some cases, a preliminary investigation can eliminate the expense of extensive soil boring and testing. The preliminary examination usually consist of at least one test boring at the site, the purpose of subsurface exploration (test boring) is primarily to establish three things: (1) obtain soil samples at various depths below the surface for the purpose of laboratory evaluation, (2) to determine the variations of the soil (soil profile) that are present on the site, and (3) to determine the depth at which free water is encountered, that is, the location of the groundwater table.

A truck-mounted drilling rig is employed to drill the test hole from which a sample of relatively undisturbed soil is gathered by using special sampling tools. The two most common are the split spoon sampler and the Shelby tube.

The Shelby tube is a thin-walled cylinder that is pressed down into the soil to the bottom of the test hole and then raised with a core inside. The split spoon sampler is used to test the condition of the soil in the bottom of the test hole and to extract a soil sample for testing. An immediate indication of the soil bearing capacity is established by using a standard weight to drive the spoon into the soil to a predetermined distance (usually a total of 450 mm in three 150 mm increments).

There are other methods, and each particular method depends on the case and requirements.

Other Methods:

Sounding rods
Augers
Test pits
Wash boring's
Rock drilling's
Geophysical instruments

A sounding rod is used to determine the depth below the surface at which rock appears and if the soil resistance is increasing or decreasing as the test proceeds.

An auger is used for bringing up samples from relatively shallow depths in soils that are cohesive enough to be retained in the tool while it is raised to the surface.

The test pitis probably the best method of examining subsurface soil because it is possible by this method, to examine the layers of earth exactly as they exist, soil moisture's are evident, and load test can be made at any desired depth.

Wash boringrequires the use of water; as a result the boring's are in the form of mud. Loose material is forced up between the drill and rod and the outer casing by water pressure and collected through an opening near the top of the casing. This is known as a wet sample.

Rock drilling employs a number of systems; among them are diamond drilling, shot drilling, and churn drilling.

The diamond drill is a diamond studded drill bit attached to a rig. The bit cuts a circular groove, and the core is forced up into a core barrel. When at the desired length, the core is broken off and brought to the surface for inspection.

Shot drillingis similar to diamond drilling except for the bit. It consists of a circular, hollow, hard steel bit with a slot around the bottom to allow circulation of shot. A flow of chilled steel shot is fed through the drill rod to the bit; as the bit turns, the shot cuts the rock and forms a core, which is forced into the core barrel and brought to the surface.

Churn drilling consist of a hard steel chopping bit attached to a drill stem inside a casing. A cable is fastened to a set of weights that raise and drop the bit,so that it strikes the bottom, chipping the rock. Water is forced down the casing, and the resulting slurry is removed.

Two basic types of geophysical instruments are used for shallow subsurface investigation and exploration: refraction seismographs and earth electrical resistivity units.These instruments have been known and used for deep exploration in oil and mineral industries.

To determine the acceptability of the soil for ground-supported slabs and foundations. Such test boring's can be made to determine soil types and the extent, the depth usually necessary to predict the performance of small and large building foundations. Have a good day!!

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Soil, Excavation, Earth moving Equipment

Keith Bray — Sat, 20 Feb 2010 20:51:08 +0000

WHAT NOW!

Brief Recap of Foundation and Soil

Shallow or spread foundations are employed when stable soil of adequate bearing capacity is sufficient and relatively near the ground surface. They are placed directly below the lowest part of a substructure and transfer building loads directly to the supporting soil by vertical pressure.

Foundations like all structures are built against failure, the design of the foundation system requires professional analysis and design by a qualified structural engineer. When designing anything other than a single-family unit on stable soil, it is advisable to have a geotechnician (engineer) undertake a subsurface investigation in order to determine the type and size of foundation system required for the building design.

Professional advice of a soils engineer experienced in a given locality would most likely be a wise thing to do, since this will mean more options and courses of action for you to consider and that, that advice could preclude the need for even a single test boring at a single-family home construction site. This is especially true when his advice is varifiable with some examination of other structures in the immediate area for evidence of apparent settlement or expansion of the soil, providing that similar conditions of soil, topography, and proposed construction is commonplace.

Soil and Excavating Equipment

The type of soil at the site, determines the type of excavating equipment needed for the job. If the soil is loose and non-cohesive (dry sand or gravel ), excavating can usually be started with a clam-shell bucket and completed with a pay-loader, a tractor with a mounted shovel, or it may be done completely by pay-loader or bulldozer. The use of these two machines require good access in and out of the excavation site. In impassable or restricted locations where such access is not possible, other methods must be used.

Cohesive soils require power equipment; in such cases, a power shovel or pull shovel (backhoe) is employed. Again, a power shovel requires access to and from the excavation, whereas a pull shovel can dig below its own level, but with slight limitations. A bulldozer may also be used for excavating cohesive soils. For very large excavations in soils of either of these types, a scrapper may be deployed.

Soils that are too soft or wet to support machinery traveling over them may be excavated by means of a drag-line. This machine will operate from one or two stable spots at the side of the excavation.

Boulders and broken rock will probably be handled best by a power shovel, though a clam-shell bucket can be used if the pieces are small enough.

When narrow trenches or individual holes are required for footings, or piers, a pull shovel or a trencher is the normal equipment to use.

Trenching

As in all excavating work, trenching excavation requires the right type of equipment. Your first step will be to decide which type of equipment works best, there are four basic types of trenching equipment:

Wheel trencher
Bucket line trencher
backhoe
Drag-line

The wheel trencher is generally used for trenching to depths of 6 feet and under providing there are no obstacles in the path (utility lines, cables, etc.,).

Bucket line trenchers are used to trench at various depths and various widths and is more efficient than the wheel trencher.

The backhoe is versatile and can cut around these obstacle with relative ease, and preferred over other trenchers because, if called for you can cut wider trenching, slope trench walls, and it is more cost effective to move to the site.

If you need a long reach and the material is soft or loose, a drag-line is best. A backhoe is incapable of operation under these conditions due to the unstable ground.

Groundwater

One serious problem regularly encountered during digging operation is the presence of water in the excavation. This may be caused by rain, melting snow, an underground stream, or the fact that the water table in the area is high. The water table is the normal level of groundwater, and if that level is close to the surface, excavating will allow the groundwater to seep and collect in the excavation. Have a good day!!

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Geotechnicians Prime concern is Cutoff

Keith Bray — Fri, 19 Feb 2010 13:41:43 +0000

Groundwater in an excavation or trench is bad news,however, this problem is common, and just, has to be dealt with. ( I'll be back! )

Hydrological Cycle

Moisture vapor in the clouds condense and by changes in temperature fall to the ground as rain snow, sleet, or hail most of this reaches the land surface and the rest is evaporated. there are four ways this water is dispersed;

Evaporation directly from the soil (flyaway)
Removal of soil water by vegetation (transpiration)
Ponds, lakes, streams, etc. (runoff)
Soaks into the soil (cutoff)

Cutoff water that soaks into the soil is of prime concern for the soil engineer,this water percolates downward through the soil pores to replenish the groundwater below. The soil acts as a vast subsurface reservoir from which the swamps, and lakes, and streams are fed during the periods between rainstorms when there is no surface runoff available. The water stored in the soil becomes the source of supply for growth and nourishment of plants, animal life, and humans.

The cutoff portion of precipitation also adversely affect many engineering structures by reducing the bearing capacity of the soil. Many problems in soil engineering involves a study of water seepage quantities through earth dams, levees, and the sides of irrigation ditches, and a study of flow into under-drains and wells. It is highly important, therefore, that an engineer should have a working knowledge of the principles governing the flow and retention of water in the soil and the effect of water upon the strength and stability of this material.

Subsurface Water

Subsurface water is divided into two general classifications, the aeration zone and the saturation zone.In more technical jargon the saturation zone or water table may be defined as the surface at which the pressure in the soil water is equal to atmospheric pressure, and is more commonly none as or termed the water table, aquifer, vadose, phreatic surface, or just groundwater, and is the deepest. The aeration zone; is everything above the water table, and includes the capillary fringe, intermediate belt (which may include one or more perched water zones) and, at the surface, the soil water belt, referred to as the root zone.

Generally, the soil water belt provides moisture vegetibles and plants; the intermediate belt contains moisture in storage - held by molecular forces: the perched ground water, if it occurs, develops from water accumulation either above a relatively impermeable strata or within an unusually permeable lens. Perched water generally occurs after a good rain and is relatively temporary; the capillary fringe contain capillary water originating from the water table.

The cutoff, or soil belt can contain capillary water available from rains or watering; however, unless this moisture is continually restored the soil will eventually desiccate through the effects of gravity, transpiration, and evaporation. In so doing the capillary water is lost. This zone is also the one most critically influencing both foundation design and foundation stability.

The water table can be determined at any time, by digging a test well or boring. As stated, the more shallow zones have the greatest influence on surface structures. Unless the water table is quite shallow, it will have little, if any, material influence on the behavior of foundations of normal residential structures. Further, the surface of the water table (phreatic boundary) will not normally deflect or deform except under certain conditions in the proximity of producing well. In this instance the boundary will draw down or recede. In other words, if the water table is deeper than about 10 feet, the boundary (as well as capillary fringe) is not likely to dome. Should upward deflection or doming occur, (it fluctuates any time in climatic conditions) it would more likely affect foundation than would any draw-down condition. The relative thickness and depth of the various zones depends upon many factors such as soil composition, climate, geology, etc.

If groundwater is found in a test hole, it is extremely important to record its elevation. The registered or recorded depth at which the water table is discovered, is vital information that will be used for project development and design for planners and engineers, and will serve as vital information for all ( contractors ) concerned with the project. This is particularly true, if the material must be excavated below water. If reliable information relative to fluctuation of the water table can be acquired from local residents or by examination of the local terrain, such information should be incorporated in the soil survey notes. Have a good day!!

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Bore holes and Saturation Zone

Keith Bray — Thu, 18 Feb 2010 15:12:31 +0000

Beware of the gusher!

Test Boring

The elevation of a water table is indicated by the elevation at which, free water rises in a test hole. Consequently, it should be realized that it takes time for the water to accumulate in the hole. The amount of time depends on the rate of flow, of the groundwater from the adjacent soils. If the soil is pervious; the water in the test hole will rise to the water table within a very short time; but if it is relatively impervious, considerable time may be required for the water to rise to the true water-table elevation.

Don't get in a tizy

A good rule of thumb, is to allow the test hole to stand for 24 hours after the hole has been dug before the elevation of the water is measured. If the soil and the region of the water table is characteristically known to befreely pervious, this time-lag period is not necessary.

Big Surprise

If, while drilling a test bore and you make an unfortunate discovery like an artisan well. "Oh Boy," your day has just begun, and mandatory overtime for everybody; this is a horse of a different color, because the flow must be stopped and the hole plugged. It gets a little hairy at this point. A helical auger may be rotated in reverse, and soil packed back into the hole. If this is not possible or if flow continues; immediately after withdrawing the auger a bentonite clay plug may be driven in with a timber, which then is cemented with Portland cement. If the flow continues it will draw down the ground water level,dry up wells, and cause surface erosion, ponding, and flooding. The worst case scenario is, a rapidly flowing uncased artisan well that will quickly erode a gaping hole that may be exceedingly difficult to plug.

Even when there is no artisan pressure, boring's in sand below the aquifer tend to cave in if the drilling tools are withdrawn, and may even cave in during the drilling operation, oweing this unfortunate circumstance to seepage of water into the drill hole, which causes a "quick" condition. This may impede penetration of the drill and result in excavation of an underground cavern. The unexpected collapse of such caverns may endanger near by foundations or the driller.

Adjustments to the Water table

A water table can be lowered artificially by providing an outlet for the groundwater at a level below its natural outlet by means of open ditches or by tile under-drains. It must be realized however, that the new water table will not be lowered to the new elevation of the drains themselves, except right in the vicinity of the drains, because the natural tendency for a water table to rise as the distance from an outlet or point of release increases. The steepness of the water table in the vicinity of the drain depends on the characteristics of the soil, being relatively flat in a permeable soil and relatively steep in a impermeable soil. Thanks for the comments. Have a good day!!

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Just tell me How Much

Keith Bray — Wed, 17 Feb 2010 13:13:13 +0000

OSHA

Specific Excavation Requirements - 1926.651

Part Number: 1926
Part Title: Safety and Health Regulation for Construction
Sub-part: P
Sub-part Title: Excavations
Standard Number: 1926.651
Title: Specific Excavation Requirements

I'm not going to list the whole regulation, but here are some you need to know prior to excavating, and please do research the rest.

1926.651(a) Surface encumbrances; (b)(1) Estimate locations of utility installations; (b)(2) Contact utility companies; (b)(3) Determine safe acceptable distance from utilities; (b)(4) When excavation is open protect underground installations; (c) Access and Egress-; (c)(1) Structural ramps; (c)(1)(i) Access and Egress ramps shall be designed by a competent person; (c)(1)(ii) Two or more structural members must be connected to prevent displacement; (c)(1)(iii) Structural members used for ramps and runways shall be of uniform thickness; (c)(1)(iv) Cleats and other attachments for ramps shall be attached in a manner to prevent tripping.

For a start check these OSHA regulations. We will look some more later.

In October of 2008 thru September 2009 OSHA was giving out citations like passing out candy! This standard is Excavations

Standard 19260651;Cited 471; Number of Inspections 283; Penalty 518279.

(To figure the average penalty amount per standard cited, use this example.)

If #cited=120 and the inspections=40, the percentage of cited inspection=3

If the penalty is 60,000 average. The current penalty amount per standard cited is $500 (120 x 500 = 60,000).

* Here are some good OSHA Standards and Regulations that cover excavations

Soil Classification - 1926 Sub-part P App A

Part Number: 1926
Part Title: Safety and Health Regulation for Construction
Sub-part: P
Sub-part Title: Excavations
Standard Number: 1926 Sub-part P App A
Title: Soil Classification

And

Sloping and Benching - 1926 Sub-part P App B

Part Number: 1926
Part Title: Safety and Health Regulation for Construction
Sub-part: P
Sub-part Title: Excavations
Standard Number: 1926 Sub-part P App B
Title: Sloping and Benching

We will look at these.

The following table is taken from this standard and it might do us some good to take a quick look at it.

Maximum Allowable Slope

Soil or Rock Type Maximum allowable slope (H:V(1) For Excavations less than 20 feet deep

Stable Rock Verticle (90 Degree)

Type A (2) 3/4 : 1 (53 Degree)

Type B 1 : 1 (45 Degree)

Type C 1 1/2 : 1 (34 Degree)

Before the excavation begins, the cost for earth removal must be factored in the equation, this estimate should be based on cubic yards of materials to be dug and hauled away. Your building plans will show the structure and the area that it is occupied by and the depth the excavation must be carried to. Because additional space is required to work around the outside of the building or forms in an excavation, a line is drawn around this additional space requirement and dug out from this line. The distance is usually two feet to the outside of the forms or building line. This line is referred to as the pay-line. The excavation contractor is paid to excavate material to this line.

When the soil is taken from its compacted position and broken up, as in excavating, it increases in bulk. This increase is called soil swell.The volume of material to be removed from the site must therefore be increased by a percentage depending upon the type of material to be moved. Most soils will swell 20% and 50%.

Soil swell percentages for common soils

Soil type Percentage of swell from Compact State

Silt 20%

Clay 25%

Sand and gravel 50%

Loam 25%

Stone 50%

If the soil is cohesive enough or if some means of supporting the sides of the excavation are to be used, the compacted volume to be removed is simply a matter of length X width X depth. But for loose, sliding soils, the excavation must have sloping sides, usually with a 1 : 1 slope. This fact must be taken into account when estimating the volume of materials to be removed.

For figuring out the slope there is another equation for that, and that I have to figured out. And as it goes If you don't use it you loose it. I've been a stranger to my mathematical genius side for some time and I need to do some refreshing, so I'll get back to you with that, once I re familiarize myself and get reacquainted.

If you have input about this equation;

YOUR COMMENTS ARE WELCOME. Have a good day!!

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Foundations

Keith Bray — Tue, 16 Feb 2010 11:13:33 +0000

The Usual Types of Foundations

Say at this juncture, you've obtained the soil engineers bore results and from these results you know what the bearing capacity of the soil is, and now your ready to proceed with your figures for the footer. This is not as hard as it might seem at first, especially when your resources are plentiful and there are other material for you to use as general guide lines and one such resource is the CABO.

Coarse grade soil with high bearing capacity (4000 pound or greater), youcan literally place your walls right on the soil, dependant upon of course, the size and (weight) live and dead loads of the structure, use, etc. But its not standard practice, stability might suffer in such cases. But in all the fifteen years working with my father building basements, I've never seen this done. On the other hand if the ground is a highly compressible soil, the capacity to bear such loads is not possible and will lead to foundation failure. However; using the chart devised by the Council of American Building (CABO) and the known results from your soils profile, your footer sizes can be estimated in the following fashion (These Estimates Are Always Assumed and one thing that I've learned through the years about assumptions was never assume anything, which I've taken as some pretty darn good advice):

Conventional Wood Frame Construction

Minimum Width of Concrete or Masonry Footings (inches)

Load bearing Value of soil (psf)

1500 2000 2500 3000 3500 4000

1 Story 16 12 10 8 7 6

2 Story 19 15 12 10 8 7

3 Story 22 17 14 11 10 9

4 inch Block Veneer Over Wood Frame or 8 inch Hollow Conc. Masonry

Minimum Width of Concrete or Masonry Footings (inches)

Load bearing Value of soil (psf)

1500 2000 2500 3000 3500 4000

1 Story 19 15 12 10 8 6

2 Story 25 19 15 13 11 7

3 Story 31 23 19 16 13 9

8 inch Solid or Fully Grouted Masonry

Minimum Width of Concrete or Masonry Footings (inches)

Load bearing Value of soil (psf)

1500 2000 2500 3000 3500 4000

1 Story 22 17 13 11 10 9

2 Story 31 23 19 16 13 12

3 Story 40 30 24 20 17 15

The most common types of foundations used in construction today are:

SHALLOW FOUNDATION

Spread Footings (also called Pad Footing)
Strip Footing (also called Wall Footing)
Combined Footing
Conventional Slab-On-Grade
Post-Tensioned Slab-On-Grade
Raised Wood Floor
Mat Foundation (close to ground surface)

DEEP FOUNDATIONS

Driven Piles
Other types of Piles
Piers
Caissons
Mat or Raft Foundation
Floating Foundation
Basement type Foundation

Shallow Foundations

A shallow foundation is often selected when the structural load will not cause excessive settlement of the underlying soil layers. In general shallow foundations are more economical to construct than deep foundations. The Spread footing, Combined footing, and the Strip footing, are the most common types of building foundations.

Spread Footing- ( also called: concrete pad, pad footing, isolated footing, single footing, individual footing, spot footing, etc. ) are footings that have square or rectangular dimensions in the plan view of your foundation plan, and are of uniform reinforced concrete thickness and are used to support a single column load located directly in the center of the footing, the load and the allowable bearing capacity of the soil determines the footer size. Economical and easy to employ and like strip footers they are normally twice the width of the supported member and 10 to 12 inches deep ( again this is dependant on the load and the soil).

Strip or Wall Footing- are often used for load bearing walls. They are usually long reinforced concrete members of uniform width and shallow depth.

Combined Footing - Reinforced concrete combined footing that carry more than one column and are often rectangular or trapezoidal in the plan view.

Conventional Slab-On-Grade - A continuous reinforced concrete foundation consisting of bearing walls, footings, and a slab-on-grade. Concrete reinforced often consisting of steel re-bar in the footings and wire mesh in the concrete slab.

Post-Tensioned Slab-On-Grade- A continuous post tensioned concrete foundation. The post-tensioning effect is created by tensioning steel tendons or cables embedded within the concrete. Common post-tensioned foundations are the ribbed foundation, California Slab, and PTI foundation.

Raised Wood Floor - Perimeter footings that support wood beams and a floor system. Interior support is provided by pad or strip footings. And a crawl space below the wood floor.

Mat Foundation- A large and thick reinforced concrete foundation, often of uniform thickness, that is continuous and support the entire structure. A mat foundation is considered to be a shallow foundation if it is constructed at or near ground level. Have a Good day!!<

/p>

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Foundation Selection

Keith Bray — Mon, 15 Feb 2010 00:47:30 +0000

Catch a tiger by his toe, if he hollers let him go; Eni, meni. minie,....?

Mat foundation. Based on economic consideration, mat foundations are constructed for the following reasons:

Large individual footings. A mat foundation is often constructedwhen the sum of individual footing area exceed one half of the total foundation area.

Cavities or compressible lenses . A mat foundation can be used when the subsurface exploration indicates that there will be unequal settlement caused by small cavities or compressible lenses below the foundation. A mat foundation would tend to span over the small cavities or weak lenses and create a more uniform settlement condition. An example of this could also be, if a foundation is built over a sanitary fill and as decomposition occurs in the soil it creates void spaces, these voids are then compressed under vertical load of the structure causing settlement.

Shallow settlement. A mat foundation can be recommended when shallow settlements predominate and the mat foundation would minimize differential settlements.

Unequal distribution of loads. For some structures, there could be a large difference in building loads acting on different areas of the foundation. Conventional Spread footings could be subjected to excessive differential settlement but a mat foundation would tend to distribute the unequal building loads and reduce the unequal settlement.

Hydrostatic uplift. When the foundation will be subject to hydrostatic uplift due to a high groundwater table, a mat foundation could be used to resist the uplift forces.

Post-Tensioned Slab-On-Grade.Post tensioned slab-on-grade are common in southern California and other parts of the United States. They are an economical foundation type when there is no ground freezing or the depth of frost penetration is low. The most common use of the post-tensioned slab-on grade are to resist expansive soils forces or when the projected differential settlementexceeds the tolerable value for a conventional ( lightly reinforced ) slab-on-grade. For example, Post-tensioned slab-on grade are frequently recommended if the projected differential settlement is expected to exceed (2 cm or 0.75 in.). Instillation and field inspection procedures for post-tensioned slab-on grade have been prepared by the Post Tensioning Institute.

Foundation selection criterion

The selection of the foundation is without saying crucial to everything else that follows. The selection of a particular type of foundation is often based on a number of factors, such as:

Adequate Depth- It must have an adequate depth to prevent frost damage. For such foundations as the use of piers, the depth of the foundation must be sufficient to prevent undermining by scour. This is a problem that your geotechnician will solve, because of the area and soil involved, they'll have historical data etc, that they use to evaluate evidences.

Or one might ask the question; Is there a standard depth which to bore for a foundation? I suppose a rule of thumb would be to bore 10 feet below the footing elevation. This could change from historical data of the site or the discovery of problem soils. However; an often sited guideline, Some Geo-techs have said; the depth should be at least two times the foundation width below the bottom elevation of the planned footings with a minimum of at least 5 to 10 feet depending on loads etc. And spread footing loads should be four times the width and is considered the most likely range to clear the seat of settlement. Consequently; neither case takes into account how earthwork may affect the seat of settlement.

Bearing Capacity Failure - The foundation must be safe against a bearing capacity failure. Bearing capacity of the soil is to support applied loads to the ground. The bearing capacity of the soil is the maximum average contact pressure exerted between the foundation and the soil which should not exceed capacity or produce shear failure.

There are three modes of failure that limit bearing capacity: general shear failure, local shear failure, and punching shear failure.

General shear failure is movement caused by shearing stresses in a soil mass and is of sufficient magnitude to destroy or seriously impair a structure. When a load is applied to the foundation, settlement occurs, and if certain load limits are exceeded, ultimate load shear failure results, a plastic condition under the footings, cause stress forces to push the soil outward and upward to the ground surface, and rotation of the foundation occurs.

Local shear failureoccurs in moderately compressible soils, and soils of medium relative density. Significant vertical settlement may take place due to local shear failure, i.e. Soil yielding close to the edge of the footing, and the yield surfaces often do not reach ground level. Similar to general shear failure but local shear failure is vertical stress that pushes outward and downward with no visible upward or turning shear stress. and like the general shear failure, may not be as catastrophic as to rotate the footer.

Punching shear failure happens in weak compressible soils, and soilsof low relative density. Considerable vertical settlement may take place with the yield surfaces restricted to vertical planes immediately adjacent to the sides of the foundation; the ground surface may be drawn down. After the first yield has occurred the load-settlement curve will steepen slightly, but remain flat.

Please leave comments.

Have a good day!!

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Foundation Selection Criterion

Keith Bray — Sun, 14 Feb 2010 07:16:04 +0000

More Points to Ponder

Settlement - The foundation must not settle to such an extent that it damages the structure. Settlement is deflection of the structure from its original setting. It is usually the result of movement or compaction of the underlying base soil and it may be due to construction on disturbed soil, backfill, and changes in the soil moisture content.

Improper construction or design deficiencies in connection with other conditions may account for such foundation movement. Building on soil with voids, insufficient compaction, and loose fill will necessitate foundation movement or deflection. Many cases of settlement are caused by contractor error in over-excavating for the foundation and footers,and then incorrectly back-filling.

Quality - The foundation must be of adequate quality so that it is not subjected to deterioration, such as a sulfate attack of concrete footings. Quality is an increasingly important concern in foundation construction. Cracks or other weaknesses in your foundation can cause many problems, and should be addressed immediately. Defects or failures in the constructed foundations can result in very large costs. Even with minor defects, remediation may be required.

Adequate Strength - The foundation must be designed with sufficient strength that it does not fracture or break apart under the applied superstructure loads (live loads and dead loads). It must also be properly constructed in conformance with the design specifications.

Adverse Soil Change - The foundation must be able to resist long-term adverse soil changes. An example is expansive soil ( silt and Clays ) which would expand and shrink causing movement of the foundation and damage to the structure.

Seismic Forces- The foundation must be able to support the structure during an earthquake with out excessive settlement or lateral movement.

The descision to use a particular foundation system that will be capable of meeting the specific requirements and specifications, will ultimately be guided by concerted efforts and contributions made by the departments of engineering, geo-tech engineers, and planning. These projected results are then factored into the structure that consequently determine the choice of footings.

Some of those factors include but are not limited to the strength and compressibility of the soil ( characteristics of the soil ) on the site, estimated loads and distribution of said loads, transmitted throughout the foundation, and the project performance criteria ( total settlement and differential settlement limitations ). So then the foundation design will be based on the assumed bearing capacity of the soil at the site.

On construction sites where settlement is not a problem, shallow foundations are, for the most part, provide an economical foundation system and are typically utilized in many residential and light framed commercial structures.

In areas where poor soils are discovered, deep foundation systems may be employed to establish adequate bearing capacity and inhibit settlement.

Enjoy! Have a good day!!

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International and Uniform Code

Keith Bray — Sat, 13 Feb 2010 04:22:00 +0000

STOP, BREAK, Hold Up!

The International Residential Code (IRC) is a comprehensive, residential code that creates minimum regulations for one- and two-family dwellings of three stories or less. It also covers all building, plumbing, mechanical, fuel gas, energy and electrical provisions. The IRC also provides a prescriptive approach and a performance approach for determining compliance.

At this point, before we get ahead of ourselves; I think its a good idea tolook at a few examples of the building codes pertaining to the information we've gleaned thus far. The codes concerning us at this point of the construction stage; where we touched on topics like, soil, grading, forms, foundations, and concrete slabs; we can see that there are specific references made for each of these tasks that by the code are addressed and as such should be followed. Here, also; I want to look into general codes, basement and retaining walls, placement of steel, because these subjects will be part of the next building phases that we'll discuss in future post. You should familiarize yourself with these and many others, including local standards and amendments as well. The code specifications and requirements listed here touch on some of the pertinent points we've previously covered, and as we proceed I'll make reference to other specific building codes that certainly matter.

Before we leap into the trenches, lets see what these codes cover and the specific requirements needed to do the work right.

Soil, Grading and Drainage

The International Residential Code ( IRC ) and the Uniform Building Code ( UBC ) specification states that the grading from the foundation should be a minimum of 6 inches to every 10 feet within the first 10 feet from the foundation. IRC [401.3] UBC (1838.2). Keep in mind the exceptions to the rules are for example; in the case of local amendments or requirements (EXC).

Damp Proofed concrete and cement masonry units (CMU) foundations enclosing habitable or usable space require drainage, exception to the cited rule (EXC)..................03 IRC [405.1] 97 UBC (1834.1)

Where underfloor area is on the same grade as exterior, alternative to the cited rule (OR) IRC [405.1X] UBC (1834.1X)

In well-drained ground or sand/gravel mixture...........IRC [405.1X]

Foundation minimum is 12 inches plus 2% above street drain........IRC [403.1.7.3] UBC (1806.5.5)

Foundation and slabs on expansive soils isolated from the expansive soil or designed to prevent damage.........IRC [403.1.8] UBC (1804.4)

Forms

Lot slope greater than 1:10 foundation and footing stepped or level.....IRC [403.1.5] UBC (1806.4)

Utility or other trench may not undermine the footing..........IRC [2604.4] UBC (313.3)

Foundation sizing IRC [403.1.1] UBC (1806.1)

One floor supported by foundation

Depth into previously undisturbed soil 12 inches
Wall thickness 6 inches
Footing thickness 6 inches
Footing width 12 inches

Two floors supported by foundation

Depth into previously undisturbed soil IRC [12 in.] UBC (18 in.)
Wall thickness 8 inches
Footing thickness 7 inches
Footing width IRC [12 in.] UBC (15 in.)

Three floors supported by foundation

Depth into previously undisturbed soil IRC [12 in.] UBC ( 24 in.)
Wall thickness IRC [8 in.] UBC (10 in.)
Footing thickness 8 inches
Footing width IRC [17 in.] UBC (18 in.)

Excavation fee of debris and roots IRC [408.4, 506.2.1] UBC (3302)

Pockets for untreated wood beams requirement 1/2 inch air space at ends and sides........................IRC [319.1] UBC (2306.6)

Basement and Retaining Walls

General

Damp-proofing required when enclosing habitable or usable space.......IRC [406.1] UBC (1831)

Parge CMU walls prior to applying damp-proofing.........IRC [406-1] UBC (1833.3)

Foundations retaining earth and enclosing usable space requirement footing drains discharging to approved drain system.........IRC [405.1] UBC (1834.1)

No back-fill greater than 4 feet until walls anchored to floor............ICR [404.1.7] UBC (1838.1)

When required reinforcement minimum distance from soil...........IRC [404.1.1.2] UBC (n/a)

Minimum distance of vertical steel from soil side of wall

One floor supported by foundation

Thickness of wall 8 inches
Distance face of soil to center fo steel 5 inches

Two floors supported by foundation

Thickness of wall 10 inches
Distance face of soil to center of steel 6 .75 inches

Three floors supported by foundation

Thickness of wall 12 inches
Distance face of soil to center of steel 8.75 inches

Basement requirements sump pumps exception group one soils........IRC [405.2.3] UBC (1834.4)

Concrete Slabs

Concrete slabs

Slab floor on grade minimum 3.50 inches thickness........IRC [506.1] UBC (1900.4.4)

Elevated or wood-supported slab requirements engineering...........IRC [2308.2] UBC (2307)

Vapor retarder joints minimum 6 inch lap under habitable space..........IRC [506.2.3] UBC (1832.2)

P.S. I enjoy the comments and stay tuned for more to come. Have a good day!!

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EQ Driving

Keith Bray — Fri, 12 Feb 2010 20:07:21 +0000

Workhorse of Earth-movers

OK we're going to look at a piece of equipment to get some ideas of what the driver see and how their work is done, and that is, in a manner that's no less than unbelievable. How do they do it! Well their is much procedural training and operation principles that they are trained in; accumulating hundreds to thousands of hours of training and field experience in order to perform their tasks, in an expedient and professional manner which are some good attributes to have because, that's what you look for in a driver. You want some one who knows how to perform the work and in the most safe and expedient manner.

Training

A driver is trained to be versed to drive different peices of equipment and at times, you'll find a driver that can practically drive every piece of heavy equipment and do all, that he's called to do with great beauty. Its uncommon but their out there. But most drivers will prefer a certain piece of equipment to operate and they know everything about that piece of equipment and will be very impressive and passionate on how they operate and how much work they can do in a short time. But you only achieve a high rate of proficiency with a high level of experience, and normally with common drivers as myself you'll get one or the other, but there is a trade off with regular operators or you may be sacrificing safety and accuracy for what might be called speed and some drivers do have it all, that comes with a price of course, but someone like me, I like to get the job done right the first time in the least amount of time and in a safe manner, but in a crunch there has to be a compromise somewhere.

Safety First

Say you want the job done quickly and in the least time possible in order to meet deadlines or what have you; well you have to give up something, or; are you willing to give up say, accuracy for the sake of speed which if and when you make that choice and problems arise you may find yourself doing the same work over again and that's "duplication of effort" which you should keep at nil to the very minimum, so work and be safe.

Description

The backhoe is an efficient earth-moving machine which combines features of several types of heavy equipment. It can dig trenches, carry heavy materials in bulk, transport large objects and work the earth in whatever way required.

Like any piece of complicated machinery, the backhoe requires a skilled operator who is proficient in the use, combinations and controls of the machines various functions. Becoming a skilled operator requires a thorough understanding of the machines capabilities and the principle behind its operation, and thousands of hours of practice.

Depending on the make and model, the backhoe usually has an overall length twenty-three feet with the boom drawn; with the boom extended the machine may stretch out to a length of thirty-five feet or more. It is at least twelve feet high with the hoe in the transport position. And with the stabilizer arms extended (lowered) the backhoe takes up to ten feet from side to side.

A backhoe operator needs to know how to operate both the front endloader and the bucket scooper. The front end loader is not as complicated as the backhoe attachment, but the operator must learn to use the stick controls while simultaneously driving the tractor. The front end loader will both, remove excess dirt and materials from the site or place it back in the whole, the process called back-filling. The front-mounted bucket can also tamp down loose soil and create a level grade.

To learn a whole lot more about heavy equipment and equipment operation and training go to this website www.youtube.com/watch?v=elvp5DdrcN8 you'll be glad you did.

Thanks for all the comments and more to come. P.S. I apologies, but I don't know how to translate comments in foreign languages. YET! But I'll get back on that. Have a good day!!

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OSHA and Construction

Keith Bray — Thu, 11 Feb 2010 07:28:48 +0000

Excavation, Trenches, and Shafts

A permit issued by DOSH (Division of Occupational Safety and Health) is required prior to starting work on excavations, trenches, and shafts which 5 feet or more deep and into which employees are to enter. 8 CAC 341

Prior to excavating the location of underground utilities must be determined and utility owners must be advised of the proposed work 1540 (a)(1)

Excavation

Before any employee may work in or adjacent to the excavation, the employer must inspect any excavation for hazards from possible moving ground 1540 (a)

Excavation must be inspected by a qualified person after every rainstorm, earthquake, or other hazard 1540 (a)(3)

Excavation Shoring System

Shoring must be properly designed and consist of sound wood timbers, and sheathing or sheet piling as needed 1540 (c)

The sides or walls of an excavation may be sloped at 3/4: 1 (horizontal : vertical). Where the soil is unstable, a greater slope is required 1540 (d)

Sloping may be combined with shoring.

Benching

The sides of excavations or faces may be guarded by cutting back 1/2 the face 1544 (b)

Excavation Safety Rules

There must be proper, qualified supervision at all times during excavation. 1540 (g)
Safety provisions must be taken to protect workers while installing or removing shoring systems. 1540 (h)
Special safety provisions must be taken to protect workers in areas subjected to vibration or extra loads from heavy equipment. 1540 (j)
Spoil must be kept back at least 2 feet from the edge of all excavation. 1540 (f)
Safe and convenient access to excavation must be provided. 1540 (i)
Effective barriers must be installed at excavations adjacent to mobile equipment. 1540 (n)
Water must not be allowed to accumulate in any excavation. 1540 (m)

Trenches

Trenches are excavations in which the average depth exceeds the width, and the width is 15 feet or less at the bottom. Shafts, tunnels, or mine excavations are not trenches. 1540

All trenches 5 feet or more deep must be guarded against the hazard of possible moving ground. Trenches less than 5 feet deep must also be guarded when this hazard exists. 1540 (a)

Trenching Safety Rules

Before entry into a confined space, the air must be tested for dangerous contamination and / or oxygen deficiency. 5158 (c)
Exit must be provided at 25 feet interval for all occupied trenches 4 or more feet deep. 1541 (b)(2)
Safe crossovers must be provided when needed 1541 (c)
Safety provisions must be taken to protect workers engaged in installing shoring 1541 (b)(1)
Covers placed over open trenches in roadways must be secured against displacement.

Large excavations must be inspected daily. 1546 (a)

Excavation Guarding

The walls and face of all excavations 5 feet or more deep, into which employees will enter, must be guarded by a shoring system, sloping the ground , or other equivalent means. 1540 (b)

Alternative shoring or sloping systems may be used only when designed by a civil engineer. 1540 (c)(4)

Heavy Construction Equipment

General

Repairs must not be made to power equipment until workers are protected from movement of the equipment or its parts. 1595 (a)

Wherever mobile equipment operation encroaches upon a public thoroughfare, a system of traffic controls must be used. 1598 (a)

Flagmen (wearing high-visibility vest) are required at all locations where barricades and warning signs cannot control the moving traffic. 1599 (a)

Job-site vehicles must meet design requirements as follows:

Operable service, emergency, and parking brakes. 1597 (a)
Two operable headlights and taillights for night operation. 1597 (b)
Windshield wipers and defogging equipment are required. 1597 (c)
Seat belts are required if the vehicle has Roll-Over Protective Structures (ROPS). 1597 (f)
Fenders or mudflaps are required. 1597 (g)

Vehicles used to transport employees must have adequate seating 1597 (e)

Vehicles (and systems) must be checked for proper operation at the beginning of each shift. 1597 (h)

Thank you for the comments and do go back to the previous post and check the heavy equipment training link for all you want to know about backhoe operations and training.

Have a good day!!

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INSTALLATIONS / SAFE EGRESS

Keith Bray — Wed, 10 Feb 2010 16:06:23 +0000

Finding installations

Your utilities ( gas, water, electric, sewer, cables, and others that you can generally expect to be underground ) should already be marked. And normally the utility company will have them marked with in a proximity of about two feet of the exact location. If a contacted utility representative is unable to respond to a notice or request to come out and locate underground installations; say, within a reasonable time frame of about 24 hours, ( check with your state and local laws, they may, by law, be granted more time ), or for whatever reason, cannot establish the exact location of the instillations the employer is allowed to proceed with operations contingent upon he continues with exhaustive efforts in the search and with caution using detection equipment to supplement his search andby every means necessary to locate installations have been used.

When excavation operation come within proximity of the estimated location of the installations. The exact location has to be determined by using more safer and delicate methods. A quick example: cutting through a fiber optic international telephone cable, depending on the size; the repair cost can start as low as $1000.00 dollars a second. ( Cha-ching! )

Utility companies for the most part are pretty good and accurate towithin two feet of the exact location, so first, you may want to try a ground probing rod to search the two by, area. But then, you have to consider the soil type to find if using the rod is feasible. If large rocks are present; "practically impossible". These soil surveys for any area of the country with the exception of a few known areas, are free if you need one. Here's a few public resources you can follow: The United States Department of Agriculture at www.usda.gov and the United States Geological Survey at www.usgs.gov and check this website also for www.topozone.com so you'll want to do some hand digging anyway, once your in this close a range to the utilities. Starting from the instillation companies location flag, you may save time by starting the dig just to the left or right of the line, perhaps; as luck would have it; who knows, the instillation may be at that exact spot.

SAFE EVACUATION

General

In every building or structure, exits shall be so arranged and maintained as to provide free and unobstructed egress from all parts of a structure or building when it is occupied. Means of egress shall be maintained free of all obstructions and impediments to full instant use in the case of fire or other emergency.

Employee Access to the Excavation

A ladder, stairway, ramp, or any other safe means of egress must be located in excavations 4 feet or more in depth. At three feet; a construction worker in a trench, on his knees, sealing pipe, connecting drainage, whatever. His life is in danger, the walls can collapse, being knelt done like that, he would be covered and not able to get up, when he exhales the weight of the soil on his back will make it difficult to impossible to take another breath, and standing in a collapsed trench, the dirt is crushing your chest restricting the ability to breath you can still suffocate. Be careful, watchful, and vigilant,ready to spring into actionespecially in a scenario as this. And these means of egress are required to be spaced no more than 25 feet apart of lateral travel for employees to exit the excavation.

In the case of a trench, egress points must be placed no more than 25 feet apart for the entire length of the trench. If an area of the trench is to be unoccupied, placing barricades or physical barriers around the area that will not be occupied will eliminate the need for any concern to set up egress points within those areas of the Trench. Also, ladders have to extend a minimum of three rungs or 36 inches above the landing and tied down.

Thanks for all the comments keep them coming.

Thanks again Have a good day!!

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Heavy Equipment Ops

Keith Bray — Tue, 09 Feb 2010 21:25:19 +0000

Careless versus Careful Trenching

The operator should always inquire as to where the locations of theutilities that may be present, the types, and depths, and take notice of such signs that may give some clues as to where these instillation may be found. the operator should learn to spot such signs of underground utilities, meters, water boxes, sewers, clean-outs, above ground conduit, electrical vaults and pull boxes, and electrical signs or lights with underground feed. Long narrow depressions could be the sign of an old trench; in paved areas, trench or pothole patches could indicate underground lines also.

The heavy equipment operator must be an observant operator and learn to spot these signs and others, that most of these troubles with utilities might be avoided.

Generally there are four steps or sets of conditions or stages of alertness, which may exist on any job site with regard to utilities. Knowing how to spot and respond under these situation or circumstances, will enable you to proceed with caution, that is vital to handling utilities successfuly.

One

When the operator is working in an area where no utilities are expected to be encountered. This would include open areas, fields, rural sites such as farmlands, or new construction areas. The operator can usually proceed ahead at full digging speed. He will work as quickly as his skills and safety will allow, but he will also be able to stop instantly, if the bucket makes contact with anything unusual. From here the operator should use an investigative procedure to determine the nature of the object.

Two

Where information about utilities is sparse, limited, or otherwiseincomplete, and the operator simply cannot tell if there are any installations present. The area will probably have some utilities, but there are no obvious signs of them. This might include most urban locations, and many open areas such as parking lots, large lawns, etc. situated in or near any sizable human population. At any rate, this condition is observed when it is believed there are no utilities present.

Here the operator can proceed at nearly full speed but he must be muchmore careful than the previous step or condition. Any bucket contact is usually checked out by hand unless the operator is certain about what he has hit.

Three

The third condition exist when it is likely there are utilities in the area. This would include any time heavy equipment is operating within the boundaries of "city property," i.e., the street, the sidewalk, or even further in some cases. Signs warning workers about utility locations may be present. In this situation, the operator must exercise great care. He should throttle the machine down and proceed very slowly. This is one instance when the operator's skills comes into play; great care must be taken at all times to avoid breaking a line. Note: Never dig on public property or within the boundaries of any public easement without obtaining utility location information first.

Four

Fourth; when the operator knows there are utilities in the area, whether marked or not. In this case, it is important to understand that officials of utility companies often make mistakes about the exact location of their lines; they will usually try to determine a line's location and its depth, but they may be wrong on both counts. If the pipe has been located accurately, however, there is practically no excuse for breaking it. And of course, there is no excuse for carelessly breaking a pipe that has already been exposed.

Obviously extreme care must be used in these situations. The machine should be throttled down to about one-half, proceeding slowly and very carefully. Anything the bucket hits should be investigated by hand.

When the operator is certain there is pipes in the area and the equipment is throttled down, he should proceed with great caution, taking only a few inches with each pass. When the bucket teeth come in contact with something, go back slightly and raise the bucket over the obstruction, and continue digging. At that point a worker should go into the trench to identify the obstruction.

Thanks for the comments, but let us be fruitful. Have a good day!!

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Clearing Obsticles

Keith Bray — Mon, 08 Feb 2010 23:56:11 +0000

Unearthing Utilities

Learning to dig around utilities and other installations is a daunting task indeed, and is not for the unskilled, nervous, or timid; these are acquired skills that an operator gains through time, training, and just plain old gut wrenching experience. Even experienced operators will at some point in time, occasionally break a pipe because, its often impossible to locate them with any amount of precision. But learning to distinguish a pipe from a rock or other buried object is an acquired talent and that comes with much time and experience on the job. The sooner this talent is developed and honed to the masters degree, the less chances there will be of delays and repairs caused by utility accidents.

Way To Go

Once a pipe is successfully located the equipment operator's job is to trench and dig around it. With extreme caution, expose as much of the pipe as possible, using the machine to your full advantage, but carefully; and then use hand labor to complete the digging, until the pipe is clearly visible from the operator's position. Once past the pipe, proceed excavating the trench as usual, taking great care not to strike the pipe with the bucket or any part of the machine.

Broken Pipes or Lines

If a pipe happens to get broken in the process, the equipment operator will know it all most immediately from the happen-stance. If it is a water line, the water will make its presence known pretty quick, and in other circumstances the operator will be able to smell, see, or hear the gas escaping from a ruptured gas line. If any kind of electrical hazard or telephone cable becomes the problem and is severed in the process, the exposed wires will be visible, jutting from the sides or floor of the trench.

What to do?

Stay calm, and think what is your best action to take keeping all in concern (that is your work mates) or keeping those that may be in the immediate area in mind. First the appropriate action should take into account the type of line it is. Once it is determined, notify the workers and the utility companies officials, those of whoms responsibility it is to make the necessary repairs. There should also be in place a training program; what signals, sirens, or horns; how many blows of the horn and what they mean ( in the case where everyone else is not in ear shot) for example; Three, two second blast of the horn should indicate an emergency situation, and be certain everyone knows.

If it is a gas line, do not shut down the equipment before getting it clearof the area. Attempting to start up any spark producing or energizing equipment in a gas cloud could ignite the fumes. If a water main has been broken remove the equipment away from the flood plain. If service to residences is involved, there is usually a shutoff valve at the street. It would be advisable to locate these shutoff valves prior to digging, so quick action can be taken if a break occurs.

In all cases notify the effected utility companies immediately of what has happened, so repairs can be made as soon as possible, and work can be resumed.

Please continue with the comments, some have been so enriching and helpful. Have a good day!!

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Pre-Footing operations

Keith Bray — Sun, 07 Feb 2010 17:18:43 +0000

Planning

The experienced equipment operator will arrive to the job site and consult with the supervisor to determine the scope of the work involved. What is expected? What are the tasking that has to be accomplished, excavation for footings, utility lines, sewers, basement, road, driveway, septic tanks, do stumps have to be pulled out of the ground,etc,. Next what needs are there in removing the spoils, will it be stockpiled, transferred, removed or loaded onto trucks? Will the land have to be cleared or graded? And will there be any demolition involved? You know these are typical assignments for the backhoe, grader, and bulldozer are called to do.

Fore Knowledge

Knowing the full scope of the job, the heavy equipment operator has to ascertain, interpret, and see the big picture of the different crafts and the stages of how the work should flow, anticipate whats ahead, have some idea in what order each stage of groundwork should be readied, and when, and how the work should move toward the accomplishment of each step and following task.

Depending on the phasing of the jobs, and tasking that are to be accomplished. The equipment driver has to formulate from those job tasks a step by step, logically, smooth and efficient game plan before he breaks ground. The where, what, when, why, and how starts here and when this stage of the plan is thought out. The operator will be able to start the dig, phase in each step and flow from one task to the next, unhampered.

Having it Together

Some important points to keep in mind when consulting about the job and job phases include but are not limited to, Utility locations, and potential problems that may arise due to the utility locations; where should materials be stockpiled, and will there be different bucket size requirements to perform certain task, and will there be any other relevant information that the backhoe for instance, is expected to perform.

No earth should be broken until all phases and sequences of the job is thoroughly thought out and planned in a logical order to avoid the operator from maneuvering himself into and unmaneuverable situation causing job delays

Gainfully Employed

The operator also has to coordinate his work with the other crafts on the site, this will mean staying in contact with the supervisor and assisting co-workers, performing such tasks as needed, in so doing, everyone can stay gainfully employed on the job.

Spoils

In addition to determining the digging sequence he will have to plan the location for stockpiling the soil, and how to go about transferring materials to and from a stockpile area if necessary. As the operator nears the completion stages of his work, he should have in mind how to wrap up the job. In considering the placement of spoils, what will eventually be done with the materials. If it is used for back-filling, it should be placed in an area that will facilitate back-filling when called for. Or, if it is to be trucked out, put the spoils in an area accessible to the loader and the truck with room to perform loading operations.

Stay tuned!
There is much more to come.

My hope is that these post are of service to you. Have a good day!!

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Layout

Keith Bray — Sat, 06 Feb 2010 01:46:48 +0000

Work-flow, Layout, and Procedure

Misunderstanding someones instructions can create problems throughout the entire job. The best way to avoid this kind of misunderstanding is to have the area clearly marked. Occasionally those in charge of the job may avoid clearly marking the excavation. This might be due to simple laziness, or more likely, they may not know where exactly where they want the operator to dig. But it's not up to the equipment operator to decide where to put the trench. That information can only come from the person in charge, and he must communicate it to the operator as exactly as possible.

Precise Layout

In some type of layouts (particularly footings), a precise layout is the most important element in completing the job with professional results. Because of the high cost of concrete and labor, it is very important to get the footings cut to the exact specifications, and in the exact locations, the first time.

Whenever the operator is called upon to perform work of this exactness, he must have a thorough understanding of the job and its dimensions. Discuss the job with those in charge until all aspects of the excavation are clear, and each step is understood completely. Go over the plans and make sure of the layout. Remember; when you start out right, you end up right; start out wrong, and you'll end up wrong.

To be structurally sound, walls must be built directly on the footing to the approved plan. Since the wall will occupy a fixed, exact location, the footing must also be in the exact location. When marking the area to be dug using a ball of string or other straight edge, along with lime or some other white powder, care must be taken to keep the marks clean, straight and narrow. Applying the marking material from a few inches above the ground will assure a precise layout.

Marking both sides of the footing is essential if the footing is to be dug wider than the bucket used. It's also a good rule of thumb to mark both sides whenever precise excavation is required.

Sometimes, excavations for plumbing or electrical lines will also require precise layouts. In plumbing, these layout will usually be called for when planning for ground floor lavatories, floor spills, or any place where pipes will come up through the concrete in a exact spot. The same requirementapply for the placement of electrical conduits.

The equipment operator should keep the following tips in mind when planning the job:

Always select the shortest and safest route through the job site.
Check terrain and soil conditions that may reduce traction or require changes in the direction of travel.
Be aware of the following obstacles, and check for them: trees, buildings, pavement, equipment, terrain embankments, personnel, and utilities (either underground or overhead).
Consider the nature of output desired and expected of the operator, the amount of earth to be moved, and the time available to perform the work.
Place temporary reference markers to indicate obstacles to be avoided: grade stakes, utility pipes or wires, thin concrete, objects that can cause tire damage, etc.
Discuss the nature of the work with other personnel involved with the job as necessary.

No operator likes to do a job the second time because of poor planing. Poor planning can be very costly when precise excavation is required, in addition to causing needless delays. When planning a job, the good operator is the one who has all his moves planned out well in advance, so that as one part of the work is completed, he will know what the next step is, and be able to move right into it without error and delay.

Backhoe Positioning

Keith Bray — Fri, 05 Feb 2010 22:51:29 +0000

Proper Positioning and Set-Up

This is where the rubber meets the road; the equipment driver has to position the equipment correctly prior to digging, the operator must understand this to operate the backhoe efficiently and professionally.

The right positioning involves lining up the machine with the trench at the optimum digging distance. The main procedures to positioning the equipment are as follows:

The center line of the backhoe, must be positioned correctly to cut the trench exactly to the layout lines.

Positioning of the entire machine is set in such a way, that easy stockpiling of spoil is accomplished and placed in the desired area.

Making sure the machine is level, in order to produce a plumb cut for the trench.

Making plans for stockpiling has to include a consideration of the area that will permit ample space or easy access to accommodate the machine and other equipment such as trucks, in order to make back-filling or spoil removal easier. Positioning of the machine in relation to the stockpile is done by placing the "arc of the swing" in the correct position. This is done by angling the machine itself in one direction or the other, relative to the excavation.

Tripod Set-Up

The backhoe can only be operated efficiently when it is positioned on a solid base. The weight of the machine should not be supported by the tires. Instead, the machine is best supported by the tripod system, consisting of the front-end-loader bucket and the two stabilizers. The advantages of using the tripod set-up out weighs the disadvantages which are very few.

Its true, some operators refuse to lower that front loader bucket while performing trenching operations. What do they think? They might blow a head gasket or something. The advantages gained from lowering the loader bucket is solid stability. Simply; efficiency is lost by not using such a support. When the weight of the tractor and loader is supported by the front tires, the machine will bounce slightly. The operator will in turn, bounce slightly also, and this motion is tranferred directly into the controls (usually causing the machine to shake even more). The backhoe cannot operate to it's maximum potential in this manner. The loss of control produced by the extra motion also cost the operator a degree of safety. This alone is good enough reason to use the tripod method. Such problems can be easily corrected by using the tripod set-up.

Another point to consider is the tendency of the backhoe to be constantly pulled backwards during the operation due to the tremendous force generated by the hydraulic system. The tripod method puts more weight on the stabilizers. This has two positive effects:

With the front bucket off the ground, the hydraulic digging force tends to lift the stabilizers off the ground, freeing the machine to roll on the front tires. The tripod set-up puts more weight on the stabilizers, keeping them firmly on the ground.

The extra weight also increases traction, which furhter prevents backhoe slippage. In this position, the operator can summon the greatest machine resistance against being pulled backwards due to the digging force.

As mentioned earlier the backhoe with the loader bucket firmly lowered on flat ground the backhoe is stabilized. Any time the loader bucket is raised off the ground, stability is decreased.

Precision Trenching

Precision set-up or positioning is called for most of the time when the backhoe must dig footings. It involves alignment of the machine exactlywith the excavation. This is performed by extending the backhoe to its farthest point desired and the operator will adjust the swing so the bucket touches the layout line at the desired point. (Once the swing is in the correct position, it is not moved until an alignment check is completed.) After this, the bucket is lifted up and pulled in to the closest part of the layout. If the bucket contacts the layout at the desired point, the backhoe is perfectly aligned to excavate that particular section of the job.

If the backhoe does not line up correctly, it can be pivoted slightly to the side, with the procedure repeated until the machine aligns perfectly with the excavation.

For more informative information on the backhoe, including a bit of history and operational principles and training visit www.youtube.com/watch?v=elvp5Ddrcn8

and www.operator-schools.com

There is much more on these sites, that I believe you will enjoy.

Thanks for the comments Thanks again for your interest; stay tuned, there is a lot more to come. Have a good day!!

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Trench and Pier Footings

Keith Bray — Thu, 04 Feb 2010 07:07:06 +0000

Get It Right!!

The excavation of footings is often said to be the most difficult operator skill to master, mainly because of the degree of precision, skill, and abilities necessary in performing the task, the backhoe operator actually builds a concrete form as the dirt is removed. Footings must be dug according to the specification on the floor and foundation plans, and the dig must be consistent throughout. Exact specifications are to be maintained, that there is no lack or overage of concrete needed and so everything will fit to their proper specification as designed, that includes reinforcing steel, etc.

If the construction work is out of specs, the contractor faces cost problems and risk failing an inspection by building authorities.

Trench-type Footing

These are generally the simplest types of footings to dig as they usually have two requirements:

Proper set-up of the equipment, to ensure alignment with the correct location of the trench.
Achieve the correct depth of the trench, including smoothing the bottom of the trench.

You must have a good mental picture of the layout of the job at hand and an excavation sequence to guide your trenching process. In the plan, you should include the amount of spoil that will be created by digging, and where it will be placed, and a step by step process where the equipment driver will leave himself an exit route upon completion of the dig.

When excavating trench footings, it is best to dig each section of the trench as long as possible, digging down to a depth to within about one foot of the desired elevation. Then, the operator should use long, level passes with the bucket, taking out about two inches at a time, checking elevation at both ends when necessary, until the desired grade is reached. Another thing; when theoperator is within about 6 inches of the desired grade, clean the sides of the trench with the bottom of the bucket, creating a clean trench area and a safe working environment.

Sometimes it may be necessary to start the trench at both ends, working toward a meeting point. Plan ahead where the two trenches will meet, so there will be enough room to complete the work.

Pier-type Footings

These are the footings usually called for when large, muti-storystructures are being constructed. They are basically large concrete platforms, either square or rectangular in shape, that will eventually support the weight of the entire structure.

Requirements for pier type footings, include straight, smooth sides that are plumb and are in the exact right location, as well as smooth level bottom at the correct elevation. The best approach to digging out pier footings, is to dig out the sides first, making sure that they are straight and correct, and then simply removing the earth remaining in the center of the footing.

For example a typical pier footing 12X12X 4 feet deep. Excavating a footing of this size will require moving 21.3 cubic yards of materials. Since the standard twenty-four inch backhoe bucket has a capacity of about One-quarter cubic yard, it will require about eighty-five full buckets to remove the required amount.

Of course, just removing the spoil from the area is not enough to finish with a professionally excavated pier-footing. Before removing the dirt, think about the requirements mentioned earlier:

Straight smooth sides that are plumb, and in exactly the right location.
And a smooth level bottom at the at the correct elevation.

Thanks for the comments.

Have a good day!!

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Dig It Right

Keith Bray — Wed, 03 Feb 2010 20:17:59 +0000

Trenching Principles

In order for the equipment operator to perform the digging operation with skill and professionalism, he has to understand the principles of how its done and the two basic requirements are, digging the perimeter in the right location according to the specification, and digging to the desired depth or elevation.

To do this the operator must have an exact layout of the trench; and a means to check the depth or elevation periodically as the operator carries out the trenching operation. A laborer is to assist him in performing this task. The depth, of the footings is one of two requirements for expert results. The main idea is to dig the depth required, but not any deeper. Some jobs are more exacting than others, and it is sometimes very difficult to dig exactly to a certain elevation and produce a perfectly flat, level bottom. It is a skill that requires total operator concentration, bucket control, and a deliberate style of cutting and correcting as the work progresses.

Elevation Check

There are several methods that are used for periodically checking the elevation as the digging operation proceeds, the most commonly used grade-checking procedure involves a builders level or transit, which is capable of pinpointing a level plan at any point on the job site. Once the instrument is set up and leveled, the grade is then checked, and the operator knows how far he has to dig to reach the bottom of the excavation.

A story pole is used with the level or transit, but a tape measure will suffice when the reference plane is within reach of the person checking the grade. When the job is especially exacting, it is absolutely necessary to check the grade as digging proceeds, at both ends of the ditch.

Measuring the depth from either side of the trench is usually unacceptable, because it is not an accurate grade check. However, this method is all right for other types of excavation, such as plumbing or utility lines, and reduces the need for constant references to elevation. When the operator and the laborer work together as a team, digging efficiency is increased. The laborer aids the operator by cleaning the grade and providing a visual grade checking function. As he pushes loose dirt down toward the machine, cleaning the bottom of the excavation, the laborer indicates to the operator how much more to cut, and warns the operator against over-digging. The operator then removes the spoil, making the laborer's job easier.

Good Work

Having an experienced backhoe operator and laborer makes digging footings more efficient, and greatly reduces the chances for error and delay. This team work greatly enhances the likelihood that the footings will be dug correctly the first time, which is of prime importance.

Appreciate the comments!

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Survey Equipment

Keith Bray — Tue, 02 Feb 2010 00:43:09 +0000

LEVELS

This tool is indispensable on the construction site, and after everything has been leveled said and done, it might be a good idea for you to do a little checking youself and make sure everything is as it should be. Here is two basic leveling tools you should familiarize yourself with: a builders level and a transit level with a graduated leveling rod.

There are many different types of these precision measuring instruments. The nuclear fusion types are a bit expensive but, (out of our range) so we won't mention those. ( that's a funny) The electronic types are a bit pricey too, with such features as; very precise and high accuracy, automatic leveling, laser guided targeting, with digital input / output readout. Price ranges from real nice $150.00 to roughly $1500.00 for the super nice. Great tools to have, but do you need one?

You really don't have to dig deep in the pocket here, just a few discriptions of levels and you can go shopping later if you want one. My father owned two, the builders level and a transit, and most of the time I was on the leveling rod. Most masonry and concrete work doesn't require none of the high tech stuff that measures to within 1/1ooo's of an inch.

Generally speaking, the builder's level is a telescopic instrument that swivels horizontally in a fix position and does not tilt vertically, and a transit is a telescopic instrument that swivel on the horizontal plane and tilts up and down on a vertical plane as well. The same as the builder's level, the transit is usually mounted on a tripod and leveled with four adjusting screws, and once in a level position on a tripod, it can be rotated 360 degree thus provides that which amounts to a level plane. But the transit can also be tilted up and down ,thus providing a plumb line or plumb.

A transit level has three main parts: the telescope, the leveling vial, and the circle.

Telescope

This is your precision sighting optical device, you can take a sighting over 200 feet by focusing on a point and centering it on the vertical and horizontal cross-hair of the scope.

Leveling Vial

This is a bubble type level that practically works the same as a carpenters level. However, it does come with different sensitivities for greater accuracy.

Circle

The horizontal circle is part of the plate on which the scope is mounted and rotates. The circle, horizontal and vertical is a graduated scale to measure angles and degrees, marked by the divisions on the circle. There are 360 degrees in a circle. The more precise transit levels have a second scale, called a vernier. A vernier lets you measure angles more precisely because it divides degrees into minutes. There are 60 minutes in a degree. An even better; more precise transit, divides minutes into seconds. Hence; 60 seconds in a minute. This means you can shoot the instrument in one direction, mark a straight line, then turn and lock the instrument at exactly 90 degrees and establish a right angle.

The pivot that allows the transit to tilt up and down is frequently fitted with precise gradations and by locking the transit at a slight incline, you can use it to maintain a precise grade when installing any type of drainage system like storm drains.

How much should you pay for a transit? Well that really depends; normally, the less expensive builder's level will most likely be sufficient for most jobs. What do your needs demand? if you need to shoot inclines and things of that nature you might invest a little more. It's a prudent investment.

Laser Level

Is a device that emits a laser beam over some distance that travels in a level plane. I suppose, the biggest advantage of using the laser level is that it isn't necessary to work with a second person. You can set it by yourself, and simply walk to where the mark is lit up.

A laser level has precisely positioned mirrors that deflects the laser beam at a 90 degree angle. Some laser levels shoot a beam that is split into 90 degree angles right, left, up, and down-all at the same time, others are equipped with a motor that continuously rotates the beam, providing a level plane.

You can use a laser level to shoot a level plane, which is the first and foremost reference for the measuring and marking process. But do you need an expensive instrument to do the job? The only difference is that you can operate the laser level without a second person, so if you do a lot of work by yourself, you might consider it.

Make sure your thoroughly familiar with the manufacturers manual, for set up, positioning and instructions on how to use it.

If you make readings in an out-of-level transit, the readings won't be true. Surveying with an out-of-level transit is a waste of time. Carelessness here can cost you everything, especially if it results in a stop work order for the whole project.

Appreciate the comments.

Have a good day!!

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Level Set-up

Keith Bray — Mon, 01 Feb 2010 08:32:29 +0000

Setting up a level or Transit

To use a leveling instrument, it must be mounted on a tripod and properly adjusted before use.

Check the tripod to make sure all the screws, nuts, and bolts are in place and properly tightened
Set the tripod in the desired location and spread the legs so that the eyepiece of the telescope will be in a comfortable position for sighting. A spacing of about one meter for the legs is generally satisfactory. The spacing of the legs should be adjusted so that the tripod head is as level as can be accomplished by eye.
Push the legs firmly into the ground. On a paved surface, be sure the points will hold securely.
Tighten the wing nuts at the top of the tripod legs into a reasonably firm position.
Remove the cap from the tripod head and place it in the instrument box. Lift the instrument from the box by the frame, not by the telescope, and set it on the tripod head. Make sure the horizontal clamp screw is loose.
Holding the level by the upper structure, screw the leveling head firmly into place.

Leveling the Instrument

Leveling is the most important operation in preparing to use the instrument. It is good practice to adopt the following procedure for four-point leveling.

Ensure that the locking levers holding the telescope in a horizontal position are locked, if a transit level is being used.
Loosen two adjacent leveling screws.
Turn the telescope so that it is parallel to two opposing screws.
Bring the bubble to the center of the level tube or vial by loosening one screw and tightening the opposite one. Try to turn them approximately the same amount simultaneously. The pressure of the screws against the leveling head should be light and only finger tight.
Move the telescope 90 degrees over the other pair of screws and follow the tightening instruction as in step 4.
Turn back over the first pair of screws and center the bubble again.
Turn back to the second pair of screws and check the levelness.
Turn the telescope 180 degrees over the same pair of screws as in step 6. The bubble should now be centered in this or any other position of the telescope.

Three-Point Leveling

The leveling sequence previously described was a four-point level using four screws to level the instrument, here is a transit level using three leveling screws to level the instrument, this is a instrument with only a circular level vial, leveling is a simple operation. The instrument is leveled by adjusting the leveling screws in pairs until the circular level bubble is brought to the exact center of the circular vial.

I've had a little trouble with this one; in that, I was able to level in one direction and it would go out if you turn it 90 degrees, the instrument may have been defective, I never really checked. Had to stop using it. I have used other transits with the three-point leveling and the circular vial and they worked just fine. I guess it was trouble enough for me to remember it and mention it? I don't know.

For instruments that have a second, tubular telescope level, the procedures are as follows:

Level the instrument by using the leveling screws and the circular leveling bubble.
Turn the instrument until the telescope level is parallel to one pair of leveling screws.
Turn that pair of screws by the same amount, in opposite directions, until the telescope level bubble is accurately centered.
Rotate the instrument 180 degrees. If the bubble does not remain centered, correct half of the deviation by adjusting the level screws and the other half by adjusting the level-adjusting screws.
Turn the instrument 90 degrees so that one end of the telescope lies over the third level screw and the other end between the first two. If the bubble is not centered, center it by adjusting the third level screw.

Some instruments with a second level have a split bubble system in the level. The telescope bubble is viewed through a viewing microscope, and if the telescope is not level, the bubble will appear to be split. When the two halves are made to coincide, the bubble is centered.

Center the lower split bubble by adjusting the level screws, as described
Bring the two halves of the split bubble into coincidence by adjustment of the tilting screw.

Thanks for all the comments.

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Adjustments

Keith Bray — Sun, 31 Jan 2010 20:26:38 +0000

Sight Adjustments

Once you have the instrument set and level, you are ready for the sight adjustments. This involves the basic instruction of these techniques and may very depending on the type of level and individual preferences.

Aim the telescope at the object or leveling rod, and sight it first along the top of the tube.
Then look through the eyepiece and adjust it for focus by turning the focusing knob until the object is clear.
Now turn the eyepiece cap or focusing ring until the cross hairs appear sharp and black.
Adjust the telescope until the object is centered as closely as possible. Do not put your hands on the tripod. Tighten the horizontal clamp screw.
Center the object exactly by bringing the vertical cross hair into final position with the horizontal motion tangent screw.

Collimation Adjustments

The horizontal cross hair is on the line of sight, which should be on a true horizontal plane for any direction in which the telescope is pointed. The vertical distance from the ground on which the tripod stands or from a stake from which measurements are being taken to that line of sight is called the height of instrument ( H. I. ).

Collimation of the leveling instrument means checking and adjusting to ensure that the line of sight through the telescope is parallel to a true horizontal plane. To check and make this adjustment, proceed as follows:

Drive two stakes, A and B, into the ground approximately 30 meters apart.
Set the instrument up close enough to stake A, ( some surveyors set the instrument some where close to the middle of stake A and B. Separate individual technique. ), close enough to stake A so that the telescope eyepiece will be within 100 mm of a level rod held on the stake. Level the instrument very carefully.
Sight through the objective end of the telescope, and, using a pencil held on the leveling rod, determine the H.I. at stake A.
Move the leveling rod to stake B, and, using a rod target, determine the distance from the top of stake B to the line of sight, (what is your line of sight measurement from the top of stake B).
Move the instrument to a point beside stake B, and repeat step 3 and 4 to find the H.I. and a rod reading on stake A.
Calculate the true difference in elevations between stakes A and B. The difference is equal to the average of the differences taken with the instrument at the two locations A and B.
Calculate the amount by which the line of sight is either high or low from stake B. Depending on whether stake A is higher or lower than stake B, add or subtract the true difference in elevation from step 6 to or from the H.I. at stake B to find the correct rod reading at A.
To make the correction,set the correct reading on the target rod held at stake A. Make the adjustment to the cross hairs, with the instrument sitting in position at B. Move the cross-hair ring up or down until the horizontal cross-hair exactly coincides with the the correct rod reading set on the target. The cross-hair ring is moved up or down by the adjustment of the upper and lower cross-hair ring adjustment screws. Turn each by the same amount so that the same tension is maintained on the adjustment screws.

Example:

H.I. reading at stake A = 1.436 m
Rod reading at B, from A = 1.017 m
Apparent difference in elevation = 0.419 m
H.I. reading at stake B = 1.306 m
Rod reading at A, from B = 1.740 m
Apparent difference in elevation = 0.434 m
True difference in elevation between A and B ( 0.419 + 0.434 ) / 2 = 0.427 m
Correct rod reading at A = 1.306 + 0.427 = 1.733 m
The line of sight was high by 1.740 - 1.733 = 0.007 m

Thanks for all the comments.

More to come.

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Leveling Rods

Keith Bray — Sat, 30 Jan 2010 20:14:49 +0000

Rod Discription

The leveling rod is an instrument that is used to find the difference in grade or elevation between two points. To do this you have to use a leveling rod, and you must be able to read it.

Some leveling rods are equipped with a straight clamp, or a round piece that attaches to the rod called a target, which can be moved up or down the rod until the horizontal target line corresponds to the instrument's line of sight ( horizontal cross hair ). The target may be mounted on a bracket held in place by friction, or, on some rods, the target is equipped with some type of clamp.

Rods may be graduated in feet and inches, or they may be graduated in feet and decimal fractions of a foot. In the latter case, the target on such a rod may have a vernier scale on it which will allow a rod reading to be made to three decimal places ( thousandths of a foot ). Metric rods, on the other hand, may be graduated in millimeters ( 1/1000 of a meter ), in 5-mm increments, or in 10-mm increments, depending on the accuracy required for the survey being done.

Rod graduations

Rods using standard units of measure are graduated in 1 foot intervals, marked in large numbers. Each 1-foot division is graduated into ten equal parts, each one-tenth of a foot, are numbered 1 through 9. Each one-tenth of a foot is graduated into ten equal parts, each equal to one-hundredth of a foot. Each one-hundredth of a foot is represented by either a black or a white band; consequently, you read to either the top or bottom of a black band to determine the correct reading in hundredths of a foot.

The metric rod is graduated in 5-mm increments, the distance between each point being 5 mm. To indicate the number of meters above the ground that the reading is taken, dots are placed beside the numbers representing tenths of a meter. On a metric unit leveling rod, the numeral 9 with three dots below it, indicates that the reading represents 3.900 m. The numeral 1 that has four dots below it, indicates that it represents a reading of 4.100 m. Some typical readings are also shown, based on the 5-mm increment rod graduations.

A leveling rod is a measuring tape or rule supported vertically, used to measure vertical distance (differences in elevation) between a line of sight and a required point above or below it. Though there are several types of measuring rods, the one most frequently used is the Philadelphia rod.

The Philadelphia rod consist of two sliding sections, which fully extended will extend to a height of 13.00 feet, closed or collapsed, the total length is 7.00 feet.

As you know there is so much more and more to come.

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Philadelphia Rod

Keith Bray — Fri, 29 Jan 2010 04:38:20 +0000

Reading The Rod

The most popular and frequently used leveling rod is the Philadelphia rod. It is a graduated wooden rod,made of two sliding sections which can be extended from 7 to 13 feet.

Each foot is subdivided into hundredths of a foot by alternate painted black gradations on a white background. Each intermediate hundredth of a foot between each pair of adjacent tenths is marked by the top or the bottom of one of the short black dash gradations, the top of the black gradation are even values, the bottom of the black gradation is odd values, the tenths are in smaller numerals (1 through 9) in black, and each foot is marked with a large red number.

Direct Reading

On a self-reading rod held plumb on a point by the rod man, reading from the face of the rod is direct reading. For readings of 7 to 13 feet the rod is used extended and is read from the back by the rod-man, the instrument-man reads the gradation on the rod intercepted by the cross hair through the telescope. If you are working with tenths of a foot, it is relatively simple to read the foot mark below the cross hair. If greater precision is required then you must work to hundredths, the reading is a bit more complicated.

For example, suppose you are marking a direct reading that should come out to 4.78 feet. If you are using a Philadelphia rod, the intervals between the top and the bottom of each black gradation and the interval between the black gradations each represent 0.01 foot. For a reading of 4.78 feet, there are four black gradations between 4.70-foot mark and the 4.78 foot mark. Since there are four gradations a beginner may have a tendency to misread 4.78 as 4.74 feet.

When sighting through the telescope, you may not be able to see the foot mark to which you must refer for the reading. When you cannot see the next lower foot mark through the telescope, you should order the rod-man to raise the red. On the Philadelphia rod, Whole feet numerals are in red. Upon hearing this order, the rod-man slowly raises the rod until the next lower red-figure comes into view. Other conditions that hinder direct readings are poor visibility, long sights, and partially obstructed sights, as through bushes or leaves, and this sometimes make it necessary to use targets.

Target Reading

In target readings, the rod-man reads the gradation on the rod intercepted by a target. The target is a sliding circular device that can be moved up or down and clamped into position. It is placed by the rod-man on signals given by the instrument-man.

The targets for the Philadelphia rod are usually oval, with the long axis at right angles to the rod and the quadrants of the target painted alternately red and white. The target is held in place on the rod by a C-clamp and a thumbscrew. A lever on the face of the target is used for fine adjustments of the target to the line of sight of the level. The target has a rectangular opening approximately the width of the rod and 0.15 ft high through which the face of the rod may be seen. A linear vernier scale is mounted on the edge of the opening with the zero on the horizontal line of the target for reading to (0.001 three decimal places) thousandths of a foot. When the target is used the rod-man takes the reading.

Thank you for all the comments and feedback on these post, and there is more to come.

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Planning

Keith Bray — Thu, 28 Jan 2010 21:05:16 +0000

WORK TO DO

The building department is your friend, especially if its time to request the building permits. You'll need a set of your plans to submit for consideration and recommendations. They have your best interest at heart as their goals are to keep the builder on course, as well as keeping you abreast of what is of vital interest, and things you should know that pertains to you. They ensure building compliance with all applicable codes, zoning regulations, requirements and that your home will stand the test of time.

The plans or blue prints are normally drawn to 1/4 inch scale on the drawing, that is one inch equal four feet on a drawing. Computer Aided Design or (CAD) is a design program that you can use to make professional drawings and designs. There are a number of these on the market that you can download that are free. If you want to try your hand at it, go to any CAD website and see whats available. I had looked at a few myself and liked them. It really comes down to personal preference and what you know about drafting and drafting programs because some of these are pretty technical and require a serious learning curve.

When I was at Osan AFB Korea, Planning section. I submitted work-order documents from customer request for work approval or for finances. This included a break down of what the customer had requested, for instance a remodel job of a certain building. This included the layout of the existing structure and the areas that were to be renovated drawn to scale, the time estimate (how long it would take to gut the existing interior walls etc.), how many crafts ( Plumbing, Electrical, Carpentry, Grounds, ect.) are needed and the man hours for each shop to do the work with the amount of time available to complete each job tasking, and the total cost estimate. Then basically the same procedure for new installation, with a material list added, and phasing of crafts and shops to perform work assignments and again the estimated time of completion and the total cost. That package was sent to Engineering for review, approval, and recommendation; mainly for cost and whether the funds were available to start the project. The package would be sent to each shop for their input, and initialed by shop supervisors and then sent back to engineering.

If the work-order or work request was approved, the package would go to Control for scheduling and to the Material Control Section for materials. If 75 to 90 percent of the material are available, the job would be started, and the whole package would go to the lead shop or shops to be coordinated and begin the first phases of the job. If the material were not available Material Control would place the work-order in materials due and the job wouldn't start until released from this section, Scheduling would hold the work in waiting for materials. Once all had been said and done, the work can be started. There is a little more involved, like scheduler meetings and things of that nature but the customer request and planning is where it all begins.

Blue Prints

The Sections of the Blue prints are:

The Plot Plan or site plan; is a schematic diagram which gives an overall view of the site and the home as it is positioned on the site, showing the shape, dimension of the property, the size and location of the building, roads and other dimensions between the construction site.

The Foundation Plan; show the location and size of the concrete footings, walls, piers, detail drawings, and the dimensions and spacings needed to install floor framing.

The Floor Plan; is a birds-eye view of the total layout of each living space, how they are arranged, the location and sizes of the doors, windows, electrical, plumbing and heating system components. Also included in the floor plan are the direction, location and spacing of the roof trusses.

Wall Sections; show the "guts" of the floors, walls, or ceilings. The wall section is drawn cut down the center of the wall to reveal the inside detail construction of the building. Both section and details are found here and are usually drawn to larger scale to better identify the critical fabrication of certain sections that would not be shown on the smaller scale.

The Elevation Plan; shows how all sides of the building will look from the finish grade up. It shows the foundation, wall height, sidings and trim work, and the roof style and pitch, roof overhang at the eaves.

Detail Plans; provide close-up views of different section of the house. Detailed drawing of small sections of the house to provide additional clarification or details needed that are not shown in the smaller scale drawings.

And other sections of importance.

If you draw your own plans the experience gained is well worth the time put into it. You'll have a better understanding of what goes into the building process and will enable you to comprehend each phase of the work; when and how it should be performed. know first-hand how all parts are to go together, how it is built, why its built, and what is built into each section, and you'll learn how to interpret the drawings as you will familiarize yourself with the terminology associated with different drawings and prints. The ability to draw and read prints come easier with experience. Practice makes perfect.

Be sure to check out other websites and links on these topics.
Have a good day!

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Reinforcing Steel

Keith Bray — Wed, 27 Jan 2010 21:34:58 +0000

Tools Of The Trade

So far, we've gone a bit into the knowledge aspect of Construction Topics and here we go again. That whosoever reads let him understand. I tried to keep these topics as basic as possible but as you well know, there is so much research that goes into construction and the ever changing technologies makes it advantageous to include what is past practice and the tons of new information and training procedures that we might glean fresh insight from that. I am from the old school of doing things, for example; using brick tongs to pick up a row of 16 bricks at one time and scaling four to five towers of scaffolds with those bricks, or using a hand held hammer to drive a single nail, some of you know what I m talking about. Now one person can take a pneumatic air nail-er and nail down a roll of 15 lbs. felt in the same time it took 5 roofers to do the same work. Not only the way these things are put together but also the why. So; with that, let us continue.

Steel reinforcement is used as a strengthener in concrete and is a reinfocer to the structure or against temperature. Structural reinforcement resist tensile, shear, and compression forces. The components of steel reinforement mainly consist of steel rebars, but welded wire fabric is also used as a concrete element.

Tensile defined by Webster: 1. of undergoing, or exerting tension 2. capable of being stretched.

The resistance of the material from being pulled apart, is its tensile strength.

Shear defined by Webster: 1. to cut with or as with shears

The resistance of the material from being cut or sheared into, is its shear strength.

The combination of steel and concrete made a major improvement over the inherent weakness of concrete: lack of tensile, stretching, strength. Concrete and steel expand and contract at approximately the same rate as temperature changes. The alkalinity of the concrete protects the steel from corrosion. The concrete bonds well with the steel. This combination allows the concrete to be used for every type of construction.

The term rebar is more commonly used than the phrase deformed steel rebar. Rebars are hot rolled with surface ribs or deformations for better bonding of the concrete to the steel. Rebar is available in 11 standard sizes and are identified by a size number that is equal to the number in eighths of an inch (1/8 inch) of bar diameter. A number 2 rebar is 2/8 or 1/4 inches in diameter, and a number 8 rebar is 8/8 inches or 1 inch in diameter. both standard billet-steel and axle-steel rebars are produced in three strength grades: 40, 60,and 75. The standard grade for building construction is grade 60. the grade numberindicates the strength in 1000 pounds per square inch (ksi).

Steel reinforcement carries and distributes loads within the foundation, transferring the loads from high-pressure areas to lower pressure areas. It thereby lessens the likelihood of point failure, either from point loading above or from lateral soil and water pressures.

Standard Markings on steel rebar

Rib markings

Letter or symbol for Producing Mill

Bar Size

Type Steel:S=Billet, I=Rail, IR=Rail meeting supplementary req., A=Axle, W=Low-alloy

Grade:The metric equivalent of grades 40, 60 and 75 are metric grades 280, (#4) 420,(#5) 520 MPa (megapascals)

There are different bar sizes for different bar material and grades

Billet or Ingot Steel ASTM Standard A 615

Grade 40: Yield Strength 40,000 (ksi) Bar Sizes 3-6
Grade 60: Yield Strength 60,000 (ksi) Bar Sizes 3-11, 14, 18
Grade 75: Yield Strength 75,000 (ksi) Bar Size 11, 14, 18

Rail Steel ASTM Standard A 616

Grade 50: Yield Strength 50,000 (ksi) Bar Size 3-11
Grade 60: Yield Strength 60,000 (ksi) Bar Size 3-11

Axle Steel ASTM Standard A 617

Grade 40: Yield Strength 40,000 (ksi) Bar Size 3-11
Grade 60: Yield Strength 60,000 (ksi) Bar Size 3-11

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Steel Properties

Keith Bray — Tue, 26 Jan 2010 16:44:41 +0000

APPLIED STRESS

Earlier we mentioned that different forces are present and cause stress on the footings and foundation, these stresses are created when loads are applied to the footings, walls, or slab, such as compressive, tensile, horizontal shear, diagonal shear. Tensile forces that twist or bend the structural members will crack a unreinforced concrete beam or slab along the bottom and the result will be structural failure. Diagonal tension will crack a slab, wall, or beam at the support, which action of the force is at an approximate 45 degree angle. Diagonal tension at a column or other support is called punching shear.

These stresses are can be found to be due to the sub grade having hard and soft spots, improperly leveled, voids,etc. It is of a critical nature that the sub-grade is properly compacted that the settling of the foundation does not settle beyond programed or set tolerances for the structural members.

The concept of reinforced concrete is simple. Concrete withstands compression forces; steel bars bear against tensile forces and shear. When these two materials are combined both in the same structural member (slab, wall, beam, girder, or column) the steel actively opposes the tensile bending and shear forces that would otherwise tear the concrete apart, and the concrete will bear up against applied compression forces that would bend the steel.

The location and amount of steel in a concrete structural component are critical and vary with the type of component, the loads that will be applied, whether the unit is pre-stressed or not, and whether the unit is cast in place or precast. For example, the reinforcement required in a simple single span beam varies considerably from the reinforcement in a beam that is continuous across several spans.

Other complications also occur. For instance, because steel is also strong in compression, it is sometimes used to resist a portion of the applied compression loads. This often occurs in columns, and in beams and girders when limiting their depth is important.

In addition steel is used in concrete even when it is not required to resist tensile and shear forces. For example, slabs on grade simply pass loads through them to the underlying base. Structural cracks in slabs on grade are due to a failure in the base and not in the concrete or its lack of reinforcement. However, slabs on grade do tend to crack as a result of drying shrinkage and when they are subjected to widely varying temperatures. Therefore a layer of light welded wire fabric is often added to them. This is not structural reinforcement, and should not be counted on to help a slab span depressions in the slab base. While it will not prevent cracking, it will hold cracks together so they are less unsightly. Some practitioners believe that welded wire fabric is not necessary in slabs on grade and routinely omit it. The Portland Cement Association's Concrete Floors on Ground suggest that welded wire fabric may not be necessary when the slab is uniformly supported and joints are located close together. The spacing of joints that would permit deletion of fabric is not specified.

Reinforcing bars are also needed in other types of slabs to resist cracks caused by drying shrinkage and temperature changes. This steel is called temperature steel. When structural reinforcement occurs, it acts to resist these stresses, and temperature steel is not required. When structural reinforcement is placed in one direction only, temperature steel is required in the perpendicular direction.

The use of concrete and steel together is made possible by the chemical compatibility of the two materials. Concrete bonds very strongly to steel, and this bond is not broken by thermal movement because the coefficients of expansion of steel and concrete are close to the same. The alkali in concrete protect steel from corroding.

Thanks for all the comments and response

Enjoy your day

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Drainage/Footing Layout

Keith Bray — Mon, 25 Jan 2010 18:42:22 +0000

Water Removal and Footing lines

Good drainage is perhaps more important than footing depth. Soils that don't drain well hold water that will cause flat soil particles in clayey soils to slide over one another acting as a lubricant. Soils that don't hold water can't freeze of heave due to cold weather. The greater the soil porousity (the larger the void spaces); sufficient portions of water will be conducted off to a local water shed or to a storm drain. A good drainage system will divert surface runoff and groundwater away from the foundation.

Positive drainage or water shed is achieved by sloping the finished grade away from the foundation at a minimum of four to six inches every ten feet and depending on the natural contour of the site swales may be installed to prevent drainage towards the foundation.

Water that settles in the foundation trench from either rain or melting snow has to be removed before your footings can be poured, there are several fixes to this predicament. But submersible pumps should be employed in a drainage channel or ditch to the outside of the trench to draw the water down to a drain hole, thereby lowering the water well below the footings. This will keep the footings dry even if there happens to be seepage or capillary water coming through from a high or fluctuating surface level of a aquifer, keeping the soil bed dry. Water should be discharged to a stream or local storm drain system.

Level batter boards and strings make it easy to set footing forms for the foundation.

The batter boards that were set up to establish your building lines are also used to guide the layout of the footing. Again the footing itself is twice the width of the wall and as deep as the wall is thick, this is rule of thumb, unless the local building codes specifies otherwise, the distance to the edge of the footing would be half the width of the wall. For the standard 8 inch block wall,the footing is 16 inches wide and 8 inches deep, with a four inch projection beyond the wall. Local code may specify steel rod in the footing but in some foundations on stable soil may not require it, or may not be required for a single familey dwelling (light frame construction) depending on what part of the country also.

To layout the footing lines, drop a plumb bob from the strings that mark the corners of your structure or use a level to establish a straight line and if a four foot level won't do, use a straight edge and a level. After the corner points are established, drive a stake or a piece of rebar into the ground to mark the corners. Measure 4 inches out from the corner stake towards the front and side, place a stake at these two location, these stakes mark the inside face of the outer form plank at a 4 inch projection beyond the wall. Repeated this sequence for the other corners as well. Once you have these stakes in place pull a string across these points to establish the inside edge of the outer footing form. Go back to check for square by pulling a measurement across the diagonals, you will have the same measurement across both diagonals. The inside edge of the outer form plank will line exactly to this string.

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Setting The Forms

Keith Bray — Sun, 24 Jan 2010 01:46:33 +0000

Framing The Footings

We left off with the layout for the forms, the material requirements will depend on what type of lumber your going to use, plywood, 2X 6, 8, 10, or 12; for light frame and just about everyday use 2X10's work perfect. If your batter boards are straight and level and your lines are hung, you should check the footing bed level and smoothness. Do this by taking a measurement at the corner of the footing, from the foundation line to the footing bed, transfer this measurement to a scrap piece of lumber ( one by scrap?) or just cut a piece to length and with this stick (story pole) check for different variation along the lengths and widths of the footing bed by spot checking the height using the pole as your standard. If you encounter high or low points in the footing bed and there is a difference of one inch, a little more or less; take a shovel and hand dig the high spot and smooth out by removing loose dirt. Never fill dirt in low spots; by all means, you always want the footings to be poured on undisturbed soil,using fill dirt will only cause problems. I made mention earlier, if there was an over cut you might fill it in using concrete and then let it set-up, anything else would pose undesirable results (unless its a new item).

If you use 2X10's as form boards, they come in a variety of lengths (as far as I can remember) up to 16 feet; start the layout at the corners, use pointed 2X4 stake 24 to 30 inches in length (you'll need a bunch of them), you can use either one by or two by material, take a short piece of form material, (one or two foot in length) the same width and thickness and set it against your outside form stake that was previously installed (this short piece is used as a spacer), place the short piece of form material on the ground beside the corner stake and drive your 2X4 stake in the ground behind your spacer, make sure your stakes are straight and plumb; drive it into the ground to just below or right at your form strings, move to the next stake placement and do the same, the placement is about every four or six feet apart between each stake. Following your form line place your stakes at all the corners of the footing. This allows you to have all the stakes in place so all you have to do is go back and nail your form to these stakes.

Set the form plank in place, up against the stakes, remembering the stakes are to the outside of the form, using double headed nails (duplex); nail the 2X10 form plank to the corner stake. (Even though your string gives you the proper height of the form, you want to re-check the height of your form to the foundation line, because at this juncture you want to be very accurate). Then at the other end of the form, drive another stake about a foot from the end and nail the form to this stake as well, keep your level following the line. (really you have some leeway, but not much; you don't want to create more work for the block mason, especially if he has to start by cutting the first run of his block; "which is waste, time, and money"), check periodically by measuring from the top of the form to your building line. If you were coming three courses to the finish foundation line, your measurement should be approximately 24 inches from the top of the form to your foundation line. Measure and fill in form pieces where needed, nail these pieces by scabbing them together and stake behind them. You can final check using a carpenter,s level.

Once you have all the outside form nailed in-place, leveled and secured, start the inside. Basically using the same techniques the way the outside was completed, the difference is establishing an inside stake for the inside corner of the form work. again establish the corners and go back to measure from the inside of the outside form plank 16, cut a 2X4 jig 19 inches long and cut a square 1: 1/2 inch corner out of both ends of the 2X4, this leaves you with 16 inches across the middle section, use this to keep the 16 inch width between your form. This is pretty simple because you know that the width of your footing is 16 inches. After setting the inside, cut a 1X3 piece of lumber 19 inches long and nail them across the top of the form between the stakes to strengthen your forms against buckling or spreading when filled.

Recheck your square, level, and height. There is no need to be sloppy about this form work, an accurately laid out footing makes every other part of the construction go that much easier, faster, and with greater precision. You want to make sure your forms are sufficiently braced and any opennings under the form are filled. Spread loose dirt around the outsides of the form and fill in any gaps in low spots On short forms, breaking or busting open due to placing the concrete rarely happens.

With taller forms, especially those that form walls, need extra precautions to make sure your forms are strong enough to with stand the pressure and the weight that is placed on these form members, but these forms are also specially built to with stand the added weight that is applied to the members, for instance; some of the form members are of heavy timber, and their placement triple their load capacity by the way in which they are placed.

Thanks for all the comments, I love to hear from you.

Stay posted and enjoy your day!

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More on Footings

Keith Bray — Sat, 23 Jan 2010 13:18:50 +0000

Check and Re-Check

From the topic of forms, concrete is our upcomming topic that we will discuss and as you might imagine, there is quite ab-it to know about concrete and its characteristics and peculiarities, a very interesting subject indeed. As you'll see, we will make an effort to cover subjects like hydration rate, curing time, slump, pliable, plastic state, workability, shrink rate, key-way, map cracking, floating, green concrete, efflorescence, flash set, and a handful of other terms that are pertinent to our topic.

Proper Bracing is Essential

The previous post ended sort of abruptly with out hardly any elaboration on the form-work, especially when there is much to be said. Well I am going to try and rectify this problem by taking up the subject again for some further elucidation on form-work; there is really much to understand because we are still dealing with the foundation of the structure and care has to be taken seriously here. Forms come under great stress due to the pressures imposed by heavy concrete and the additional stress placed on them by consolidating while placing it. Failure of a form system can cause substantial harm to those involved, therefore, the form-work must be designed and built using the same professional skills and taking the precautionary measures as you would with the building of the permanent structure. Once your past this point you can press on with the rest of the layout but until then, lets stay with the matter at hand.

All footings are formed with either wood, plywood, plastic, aluminum, metal, etc, the exceptions are earth forms, where-as the soil must be of the right composition to do so and according to local laws and where building code permit, and this stable soil is cut cleanly and accurately to the shape of the footing. An aside; lets look at this type of foundation footing. Trench footings, where the concrete is poured directly into the trench has its pros and cons. The pros, I would suppose; is that on good soil it can be installed quickly and with satisfactory results, its a good idea to have re-bar installed weather it needs it or not; the little extra expense may save larger expenses later. The cons maybe the drainage of this type of footing and in the manner in which it is installed, might be questionable, and may pose problems by inadequate water drainage that might allow seepage across the footing and flow beneath your foundation wall. The drain system is usually set directly on top of the footing instead of below it, ( check your drawings ) unless steps are taken to resolve this issue, you can expect the possibility of water seepage to occur. A possible fix might be after the footing has set. Dig a trench below the footing to install a drain along the inside and the outside of the footing.

Other Considerations

Just to mention a couple other leveling techniques, lets briefly describe them below. Although this is known by the professional craftsman, we'll take a look at these tools anyway. Stated earlier, we saw that your batter boards are level and the strings are set and pulled to the proper foundation height and in this scenario we used a storey pole as a standard to check the proper height of the footings. Other methods of finding the level of the footing, of course, is to set up your transit and shoot the corners, making sure all the corners are at the same height and then go back and spot check by measuring along the footing form. Also, you may want to use a water level; basically its a good length of clear plastic water hose stretched along the footing and filled with water; the water itself will find its own level. By checking the water mark on both ends of the hose and compare the mark to the form height, you should gain proper level of the form-work, you might use the water level to check your batter boards also, its exceptionally accurate, inexpensive and easy to use.

There is so much more to be said about footings but I can't cover them now. But we shall return with concrete, how about that!

Have a Good Day!

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Concrete

Keith Bray — Fri, 22 Jan 2010 04:56:16 +0000

What is Concrete?

Portland cement named after the limestone on the isle of Portland is considered the most used and important masonry material in modern construction today. As a building material for construction, its use is vast in its application, availability and fairly inexpensive and surprisingly, comparatively light in weight. It is commonly used for buildings, sidewalks, pavements, walls, sewers, foundations, footings, bridges, piers, abutments, culverts, retaining walls, and a number of other multiple uses. It is readily placed and because concrete is placed as a fluid it can be formed to any shape, dimension, thickness, or design, and it has high compressive strength and its very pleasing to the eye. But with all that strength, on its own it is totally incapable of being used for most concrete structure built today using concrete alone. Primary forces acting on a beam or unsupported slab are those that tend to push it together (compression) at the top of the beam or slab and those that pull it apart (tension) at the bottom. Therefore any slab or beam of appreciable length will pull apart at the bottom and collapse if a heavy load is applied to it.

In the planning and design stages of a concrete pad, pier, walls, etc., engineers understand the physical properties of concrete in its plastic and hardening state and intrinsic limitation of concrete, and incorporate reinforcement (steel) rebar and rebar gridwork that is installed to defray those concrete limitation and structural weaknesses that result from low tensile strength. The principle limitation of concrete, are:

Low tensile strength
Shrinkage and moisture movement
Permeability

When Portland Cement is mixed with water, sand, crushed stone (aggregates), it chemically combines to form crystals that bind the aggregates together. The major function of aggregate is to make concrete more economical and keeps the concrete from shrinking and cracking as the setting and hardening takes place. The result is a solid rock hard mass of material called concrete. As the concrete begins its chemical reaction between the water and cement it heats up or gives off heat and this chemical reaction that takes place is called the hydration (hardening) process. The strength of the concrete is dependant on the amount of water that is added per pound of cement, that is; how many gallons of water per bag of cement.

Portland cement is produced in huge rotary kilns producing temperatures at nearly 2700 Degree Fahrenheit. At this temperature lime, silica, aluminum and iron oxides, which are derived from limestone, oyster shells, marl, shale, iron ore and clay, undergo calcining. After cooling, the conglameration of the mix, produce greenish-black pellets called clinkers, these are then pulverized and mixed with small amounts of gypsum that controls the set time of the cement. The resultant product of the process is a very fine powder called Portland Cement. A standard bag of Portland Cement weighs 94 pounds and has a volume of one cubic foot of cement per bag.

Concrete reacts predictably and there are certain properties of the concrete mix that can be regulated or controlled, of the variables that effect its workability (ease of use) while in its plastic state, and its strength while hardening. Some understanding of the kinds of cements and aggregates, correct proportions of these, admixtures, slump, and the effects of weather during pouring and curing, will determine factors of achieving the best result, or not.

Love hearing from you.

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ConstructionTopic.com» construction topic, construction safety

Home Construction; preparation, principals & methods

Construction: Site Preperation

Construction topic 2

Getting your ducks in line

Building: Site stakes & Foundation Prep

Pre-Excavation, Precaution & Considerations

Construction Site Prep. cont...

throughout an entire year are important

References

Further Readings:

Building Lines and Batterboards

CORNER STAKES

Batter Boards

Baselines

Excavation; Process Developement

Foundation Types

Slab-on-Grade foundation systems:

Site: Grade, Layout & Building Stakes

Soils Types & Characteristic

What's The Big Deal About Dirt?

Rock Classification

Group: Igneous (Intrusive)

Characteristics

Group: Igneous (Extrusive)

Characteristics

Group: Metamorphic ( Foliated )

Classification

Group: Metamorphic ( Nonfoliated )

Classification

Group: Sedimentary ( Clastic )

Classification

Group: Sedimentary ( Nonclastic )

Classification

Soil Investigation

Soil And Foundation

Classification and Description

Footings and Excavations

Shallow Foundation

Footings

Excavations

Earth and Water

How Deep to Dig / Striking Water

Regress To Safety Then Forward

SAFETY

A ConstructionTopic Recap

Graded Soils / And What ???

Granular Soil Uses

THAT'S GOOD DIRT

Problem Soils

Soil Stability

Group I (Excellent)

GW

GP

SW

SP

GM

SM

Group II (Fair to Good)

GC

SC

ML

CL

Group III (Poor)

CH

MH

Group IV (Unsatisfactory)

OL

OH

Pt

Clays

CLAYS: GOOD STUFFF OR BAD STUFF / FYI

Basic Construction? / Investigations

The Need for Investigation

Other Methods:

Soil, Excavation, Earth moving Equipment

WHAT NOW!

Brief Recap of Foundation and Soil

Soil and Excavating Equipment

Trenching