Perimeter Foundation Insulation
Perimeter foundation insulation is required in colder climates to reduce the heat loss from a slab-on-grade to the below-grade foundation wall. In most cases, the insulation is only required up to two feet below the grade since heat loss in the soil is negligible. In mild climates a 12-inch depth is sufficient.
• Nominal 2-inch-thick extruded polystyrene, cellular glass, or other closed-cell type rigid board.
• Adhesive material recommended by waterproofing system manufacturer.
• Apply rigid insulation to vertical below grade foundation wall.
• Backfill as required.