Slab Foundation for Cold Climates
Foam insulation below the concrete makes deep footings a thing of the past.
Every builder knows that conventional footings must be placed lower than the deepest expected frost depth. For a garage slab, my area’s 42-in. frost depth usually means deeply excavating perimeter trenches, pouring concrete footings, and building concrete or CMU-block stemwalls atop the footings. Then backfill the stemwalls, add a layer of gravel and a plastic vapor barrier, and then pour a 4-in.-thick concrete slab. There had to be a better way.