Frost heave caused by ice lenses can wreak havoc on foundations in cold climates, often driving builders to dig below the frost line. Yet, Section R403.3 of the International Residential Code (IRC) outlines a clever alternative: the frost-protected shallow foundation (FPSF). By placing insulation around a heated slab, the building’s own warmth keeps soil from freezing at critical edges. This article explores the mechanics behind FPSFs, outlines essential code requirements, and highlights what inspectors should watch for in the field.
This article is your walkthrough of the code’s intent, the nuts and bolts of FPSF design, and how to spot problems during inspections.
Very interesting, Ben. The video was well done. The explanation as well well done.
Tutorials like this help embed the Frost Protection Shallow Foundation building process in the inspectors mind and assists them in defect or deficiency determination at the inspection site itself, or in the office building a report.
Not unusual here in far northern MN, just south of the border. In floor heat, shallow footing, foam insulation skirting. My own house of 15 years is built this way. Excellent system when a basement cannot be built (due to shallow soil depth over bedrock).
