Dwellings in Wisconsin are regulated according to the Uniform Dwelling Code, which is contained in Chapters Comm 20 to 25 of the Wisconsin Administrative Code. Chapter Comm 21, entitled "Construction Standards," provides the details for constructing a code-approved foundation. Here are some of the key points.
Footings must be eight inches deep and four inches wide on each side of the foundation wall. The bottom of the footing must be at least 48 inches below the finished grade to prevent frost heaving.
Reinforced concrete walls are generally required to be at least eight inches thick. An approved damp-proofing material must be applied to the exterior surface of all masonry foundation walls.
If you have a basement foundation with a concrete floor, the concrete must be at least three inches thick. If the floor area has clay soil, a four-inch layer of sand or gravel must be placed on top of the soil before pouring the concrete.