Insulation Between Floor Joists In Crawl Space

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.

Insulation between floor joists in crawl space.

When the basement or crawl space has vents installed insulating joist bays. Install an air and vapor barrier over the floor and tape it to the insulation. Where winter temperatures are extreme opt for insulating the walls and sealing off the crawl space entirely. Floor insulation for moderate climes popular reads.

However the insulation needs to be treated with a fire retardant. In moderate or dry climates without the threat of sustained subfreezing temperatures insulation between floor joists makes sense. Instead install fiberglass batting between the joist bays which are the spaces between each set of floor joists. Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates.

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. 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. Gaps between the insulation and the floor can lead to inefficiency and heat loss.

Use caulk or foam sealant to seal the joint between the top of the crawl space wall and the sill. If your space has them avoid adding insulation to the crawl space walls. Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances. 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.

This type of insulation allows for conditioned air to be introduced into the crawl space. Don t compress the insulation as it requires its loft in order to maintain its rated r value.