Foam Board Insulation Between Floor Joists

Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances.
Foam board insulation between floor joists. Step 5 seal. 4d extend insulation into joist space to reduce air flows. If it you need to spread it use a brush to help cover and smooth out the glue. Place back between the joist and hold it in place for five seconds or for how long the instructions on the glue says.
Rigid foam is the best insulation for rim joists. 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. Unlike fiberglass rigid foam insulation does not absorb water support mold or allow air to pass through.
4c as an alternative to floor insulation foundation walls of unvented crawl spaces. Instead of installing the foam insulation between floor joists in the crawl space the foam board is installed against the crawl space foundation walls. When the basement or crawl space has vents installed insulating joist bays. You want it snug but not to.
We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier.