The Residential Code of Ohio requires a minimum depth of 32 inches from the finish grade to the bottom of the footing. The load-bearing value of the soil conditions in pounds per square foot must be used to establish the minimum size. At 28 days air-entrained, concrete in footings must have a specified compressive strength of not less than 2,500 PSI. 9. For clay soils, the required depth is 36 inches. The code also requires that each footing be provided with two 8-inch by 12-inch openings at least 3 feet apart. These allow water to drain away from the house and prevent any obstruction of storm sewers or other utilities. Footings are required for all exterior walls over 4 feet high. The wall may be constructed out of brick, stone, tile, or masonry, as long as the total thickness is no more than 8 feet. If you plan to use a cement slab as the flooring material, then the depth of the footing should be equal to the slab's thickness. The code does not specify a maximum width or length for footings. However, field tests have shown that footings between 30 and 50 inches on a side are sufficient to meet code requirements. Larger or smaller footings can be used depending on your design needs. Ohio building codes require footings to provide support for the weight of the building above them. This ensures that the building will remain upright under its own weight even if the ground underneath it is unstable.