Frost-protected shallow foundations
provide a third alternative.
One of the most promising techniques, the NAHB says, is "frost-protected shallow foundations
." This technique allows builders in cold climates to start foundations 12 inches below grade instead of at a frost line that may be 3,4 or 5 feet deep.
The NAHB Research Center coordinated the projects; the results are published in a report tided "Substantiating Data and Information for Frost-Protected Shallow Foundations
," along with the "Design Guide for Frost-Protected Shallow Foundations
The Council of American Building Officials has opened the door to frost-protected shallow foundations
, a decision that could trim housing costs in some markets as much as $2,500 a house, according to NAHB.