Excavation; Process Developement

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.