Rigid foam insulation is a dense, stiff material made from polystyrene, polyurethane, or polyisocyanurate, and is known for its high insulation value and durability. It is the favored insulation for crawl space inside walls. Rigid foam insulation works for any type of masonry wall: concrete, block, brick, and even stone.
One of the main benefits of rigid foam insulation is its high insulation value, which means it is able to provide a high level of thermal resistance with a relatively small thickness. This makes it an efficient choice for many applications, especially in basement walls.