Standard Basement Concrete Footer

Description

• The standard footer for a basement foundation consists of a horizontal layer of poured concrete cast into a trench dug around the bottom of the pit excavated for the basement. Concrete footers usually have a width about twice as wide as the wall it supports and a thickness, or depth, about the same as the wall. A standard footer remains flat throughout its entire length, however, stepped footings, which rise in a staircase fashion, sometimes appear in foundations that change elevation.

Soil

• The type of soil on which a footer rests plays a large role in its stability. Footings placed in soft soil may settle more than normal and cause structural damage to the home. Although even settlement, as long it stays under half an inch, is not necessarily a case for concern, uneven settlement typically points to a structural problem you need to address. Soil around the footers needs compacting to help prevent any movement.

Widen

• When a builder encounters an area of soft soil under a footing location, one option is to dig deeper until he hits an area of heavier soil and build taller basement walls. He can also simply widen the footer, making it more able to support loads even when resting in softer soil. You must increase a footer's depth if you increase its width. The depth of a footing should at least equal to the space between the supported wall and the footing edge.

Frost

• You should build footings below the frost line, which is the lowest level at which the ground freezes. Frost subjects soil to enormous pressure that can lift houses or move basement walls. Placing the footers under the frost line prevents any movement of the house. You rarely need to worry about frost penetrating anywhere near the footings when the basement remains heated. In unheated basements, however, the frost can penetrate well below the basement floor. Footings installed at the proper depth avoid any potential damage from frost penetration due to cold basements.