Behind brick veneer or under slab, the insulation that compresses or absorbs moisture is the insulation that fails before the building does. Extruded polystyrene holds its R-value when it gets damp — the closed-cell structure doesn't absorb water the way other foams do, and it doesn't compress under concrete pour or backfill. 3/4-inch thickness fits the standard air gap behind brick veneer without eating into the wall cavity, and handles below-slab applications where direct ground contact demands moisture resistance. The 4x8 sheet covers 32 sq-ft per sheet with minimal seams — fewer seams means fewer thermal bridges where heat conducts around the insulation. What concrete and masonry contractors across northeast Nebraska and northwest Iowa specify for brick ledge protection and below-grade Stocked at Crofton Lumber and Akron Lumber.