Foam Board Insulation Floor Joists

Rigid foam is the best insulation for rim joists.

Foam board insulation floor joists.

4d extend insulation into joist space to reduce air flows. 4b slab floors built directly on the ground. Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below. If you need to insulate these rim joists it s best to hire a cellulose insulation contractor.

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. Instead of installing the foam insulation between floor joists in the crawl space the foam board is installed against the crawl space foundation walls. Two story homes usually have another ring of rim joists above the first floor ceiling. Unsealed rim joists rob homeowners of money energy efficiency and comfort.

You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling. Fill gaps and penetrations greater than 2 quickly and affordably with the froth pak spray foam sealant kit. Unlike fiberglass rigid foam insulation does not absorb water support mold or allow air to pass through. We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier.

Low pressure foam how to seal rim joists. This method can be hundreds of dollar less than the cost of using the commercially applied spray foam. 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. 4c as an alternative to floor insulation foundation walls of unvented crawl spaces.

But insulating your floors is a good idea for many reasons including energy efficiency and height adjustments. You want it snug but not to. Seal and insulate using rigid foam board insulation.