Crawl Space Floor Joist Insulation

Crawl space insulation basics.

Crawl space floor joist insulation.

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. 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. Silverglo rigid foam insulation won t absorb water or support mold growth and does not allow air infiltration making it the perfect insulation product for use on crawl space walls.

In moderate or dry climates without the threat of sustained subfreezing temperatures insulation between floor joists makes sense. However the insulation needs to be treated with a fire retardant. Where winter temperatures are extreme opt for insulating the walls and sealing off the crawl space entirely. Insulating and air sealing this perimeter zone is important because it s a major source of air infiltration and conductive heat loss.

While this method does work in the very short term moisture eventually builds in the crawl space and grows on this highly porous surface. If your space has them avoid adding insulation to the crawl space walls. 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. Don t compress the insulation as it requires its loft in order to maintain its rated r value.