Insulation Between Floor Joists In Crawl Space

Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates.

Insulation between floor joists in crawl space.

If your space has them avoid adding insulation to the crawl space walls. 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. Don t compress the insulation as it requires its loft in order to maintain its rated r value.

This type of crawl space also allows insulation with an r value of 19 installed in the floor joist if the crawl space and has a permanently installed dehumidifier. Instead install fiberglass batting between the joist bays which are the spaces between each set of floor joists. Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances. This type of insulation allows for conditioned air to be introduced into the crawl space.

It is important to secure insulation and cover it with a vapor barrier in order to prevent moisture and the mold that often follows close behind. Where winter temperatures are extreme opt for insulating the walls and sealing off the crawl space entirely. In moderate or dry climates without the threat of sustained subfreezing temperatures insulation between floor joists makes sense. Use caulk or foam sealant to seal the joint between the top of the crawl space wall and the sill.

Install an air and vapor barrier over the floor and tape it to the insulation. Floor insulation for moderate climes popular reads. Gaps between the insulation and the floor can lead to inefficiency and heat loss. Unlike fiberglass rigid foam insulation does not absorb water support mold or allow air to pass through providing that joints between boards are sealed with tape.

If the crawl space is ventilated which is ideal because it aids in the elimination of moisture then fiberglass insulation can be easily installed under the subfloor between the floor joists. The fiberglass will also need to be secured in place using wire mesh twine wood laths or other securing methods which can be an intensive project that adds to the overall cost.