Instead, for do-it-yourselfers, the easiesttype of insulationto use is rigid foam on the walls.
With a plastic vapor barrier on the floor, the two materials are joined with tape.
The plastic is a 6 mil or thicker reinforced polyethylene plastic sheeting.
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But moisture eventually builds in the crawl space and grows on this highly porous surface.
Moisture-laden fiberglass will sag and fall.
It is the favored insulation for crawl space inside walls.
This makes it an efficient choice for many applications, especially in basement walls.
All avenues to the outside are shut off or sealed with caulk.
Redirect downspouts that may be forcing water alongside the foundation walls.
Look at Interior Sources of Moisture
Water can also come from within the house.
Look at pipes running through or within joists.
Load up the caulking gun with exterior-grade caulk and insert caulk into cracks and holes.
In some areas where radon gas is a concern, the space shouldn’t be completely sealed.
Seal Rim Joists and Sills
Go inside the crawl space during the day.
Turn off the flashlight briefly and examine rim joists and sill areas for outside light shining through.
With the light back on, seal up these cracks with the silicone caulk.
For large cracks, use low-expansion foam insulation.
Aim for as few seams as possible by installing large sheets of foam.
Seal seams between the boards with PVC tape.
Make cut-outs for every protrusion such as piers and posts.
launch the vapor barrier up against these protrusions and seal them tightly with the butyl tape.
Seal seams between separate vapor barrier sheets.
If you live in a humid area or flood zone, encapsulation may not be a good idea.
Encapsulation is more costly.
Thefoam boardfor the walls is typically considered avapor barrier, as well.
The project can be especially difficult due to limited access to the crawl space.
