Best Insulation For Floor Joists In Crawl Space

Where winter temperatures are extreme opt for insulating the walls and sealing off the crawl space entirely.

Best insulation for floor joists in crawl space. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists. The best insulation material for crawl spaces is rigid foam insulation board. Don t compress the insulation as it requires its loft in order to maintain its rated r value. Instead of installing the foam insulation between floor joists in the crawl space the foam board is installed against the crawl space foundation walls.

If your space has them avoid adding insulation to the crawl space walls. Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates. This type of insulation allows for conditioned air to be introduced into the crawl space. 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.

Fiberglass insulation is usually the best option though handling fiberglass can be dangerous and it is not the most eco friendly option in some cases. Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space. Use an insulation that. 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.

Lay an insulating mat over the crawl space floor. Dim light filtered in from vents in the walls. Stapling fiberglass batts between joists to the underside of your home s floor presents a number of problems. The insulation should press right up against the floor between joists.

Instead install fiberglass batting between the joist bays which are the spaces between each set of floor joists. While this method does work in the very short term moisture eventually builds in the crawl space and grows on this highly porous surface. 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. However the insulation needs to be treated with a fire retardant.

Batts of soggy fiberglass insulation hung haphazardly from the joists. In moderate or dry climates without the threat of sustained subfreezing temperatures insulation between floor joists makes sense. Crawl space insulation basics.