Foam Board Insulation Floor Joists

4d extend insulation into joist space to reduce air flows.

Foam board insulation floor joists.

Most people do not think about insulating their floors unless perhaps it s their attic floor. 4c as an alternative to floor insulation foundation walls of unvented crawl spaces. 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. Fill gaps and penetrations greater than 2 quickly and affordably with the froth pak spray foam sealant kit.

You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling. Instead of installing the foam insulation between floor joists in the crawl space the foam board is installed against the crawl space foundation walls. Unsealed rim joists rob homeowners of money energy efficiency and comfort. 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.

Two story homes usually have another ring of rim joists above the first floor ceiling. Foam board insulation is used on attics and walls yet it can also be used to insulate your floors. We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier. Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below.

Seal and insulate using rigid foam board insulation. You want it snug but not to. Unlike fiberglass rigid foam insulation does not absorb water support mold or allow air to pass through. Low pressure foam how to seal rim joists.

Rigid foam is the best insulation for rim joists. 4b slab floors built directly on the ground. If you need to insulate these rim joists it s best to hire a cellulose insulation contractor.