Foam Board Insulation Floor Joists

Instead of installing the foam insulation between floor joists in the crawl space the foam board is installed against the crawl space foundation walls.

Foam board insulation floor joists.

4d extend insulation into joist space to reduce air flows. If you need to insulate these rim joists it s best to hire a cellulose insulation contractor. 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. Fill gaps and penetrations greater than 2 quickly and affordably with the froth pak spray foam sealant kit.

This method can be hundreds of dollar less than the cost of using the commercially applied spray foam. Unlike fiberglass rigid foam insulation does not absorb water support mold or allow air to pass through. Unsealed rim joists rob homeowners of money energy efficiency and comfort. Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below.

You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling. Foam board insulation is used on attics and walls yet it can also be used to insulate your floors. But insulating your floors is a good idea for many reasons including energy efficiency and height adjustments. The best insulation material for crawl spaces is rigid foam insulation board.

We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier. A do it yourself friendly method for sealing and insulating the rim joist or band joist area is to use rigid foam up against the rim joist. You want it snug but not to. Most people do not think about insulating their floors unless perhaps it s their attic floor.

Rigid foam is the best insulation for rim joists. Seal and insulate using rigid foam board insulation. 4b slab floors built directly on the ground.