Foam Board Insulation Floor Joists

Unlike fiberglass rigid foam insulation does not absorb water support mold or allow air to pass through.

Foam board insulation floor joists. Low pressure foam how to seal rim joists. To prevent these problems only air impermeable insulation either rigid foam or spray polyurethane foam should be used to insulate the interior of a rim joist. You want it snug but not to. Unsealed rim joists rob homeowners of money energy efficiency and comfort.

Seal and insulate using rigid foam board insulation. 4c as an alternative to floor insulation foundation walls of unvented crawl spaces. This method can be hundreds of dollar less than the cost of using the commercially applied spray foam. 4d extend insulation into joist space to reduce air flows.

Fill gaps and penetrations greater than 2 quickly and affordably with the froth pak spray foam sealant kit. 4b slab floors built directly on the ground. Foam board insulation is used on attics and walls yet it can also be used to insulate your floors. Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below.

But insulating your floors is a good idea for many reasons including energy efficiency and height adjustments. Two story homes usually have another ring of rim joists above the first floor ceiling. Instead of installing the foam insulation between floor joists in the crawl space the foam board is installed against the crawl space foundation walls. The best insulation material for crawl spaces is rigid foam insulation board.

If you need to insulate these rim joists it s best to hire a cellulose insulation contractor. Rigid foam is the best insulation for rim joists. We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier.