Indiana Frost Protection Methods for Foundations

Indiana rewrote Section R403.1.4.1 of the residential code to list the acceptable methods explicitly. Foundation walls, piers and other permanent supports must be protected from frost by one or more of four methods: extended below the frost line specified in Table R301.2(1), constructed in accordance with Section R403.3, constructed in accordance with ASCE 32, or erected on solid rock. Section R403.3 is the frost-protected shallow foundation method, which uses insulation to keep the ground beneath the foundation from freezing rather than placing the footing below the frost line; ASCE 32 is the referenced engineering standard for the same approach. The section also carries a flat prohibition, footings shall not bear on frozen soil unless the frozen condition is permanent, and an exception for freestanding accessory structures of 721 square feet or less built in accordance with Table R309.

Which method you are using has to be evident on the permit drawings, because the inspector is checking a different thing in each case: bearing depth for a conventional footing, insulation placement and extent for a shallow frost-protected one. A foundation that matches none of the four methods will not pass the foundation inspection. The prohibition on bearing on frozen soil is enforced at the time of placement, which in practice constrains winter work.