How To Insulate Bottom Of Floor Over Crawl Space

To insulate the crawl space i would use a closed cell two pound 907 gram spray foam because it will act as both your vapour barrier and insulation.

How to insulate bottom of floor over crawl space.

Fiberglass insulation on the floor joists in a crawl space will help keep the floor above warm. Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a 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. Applying spray foam to the dirt floor of your crawlspace may be one of the easiest and most effective solutions and if so then you would be best not to insulate the joists over your head and just heat that space instead.

Seal seams between the boards with the pvc tape. Cut pieces of insulation just large enough to fit along the rim joist the framing material into which all the floor joists are nailed. Cut rigid foam pieces to size with the saw and attach the pieces to the inside crawl space walls with the latex adhesive. 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.

This will give you the thermal barrier between the crawl space and your living space as well as help keep the air from getting from the crawl space into the living space. Install an air and vapor barrier over the floor and tape it to the insulation. The sill plate is the first piece of framing lumber and it runs on top of the crawl space wall. Aim for as few seams as possible by installing large sheets of foam.

It will also help to stop that echo that can be heard when you walk on the floors suspended over a crawl space. You could also use batt insulation but don t. When you re using fiberglass batting insulation material run it about 6 inches or so onto the crawl space floor. Insulate the crawl space walls.

However in a moist ventilated crawl space this insulation will eventually rot and become soaked with moisture. This will cause it to fall off the ceiling and on to the floor.