Does the residential code require footings to frost for all buildings?
A. No. Section R403.3 entitled Frost protected shallow foundations provides that for buildings where the monthly mean temperature of the building is maintained at a minimum of 64F (18C), footings are not required to extend below the frost line when protected from frost by insulation in accordance with Figure R403.3(1) and Table R403.3. EXCEPTIONS: 1. No foundation not so protected may be attached to frost-protected shallow foundations. 2. Unheated garages, porches, utility rooms and carports shall not be permitted to be attached to dwelling units with a frost-protected shallow foundation. Materials used below grade for the purpose of insulating footings against frost shall be labeled as complying with ASTM C 578.
