What Are My Options For Crawl Space Insulation?
1) Fiberglass Batt Insulation:
Fiberglass batt insulation installed under floors can be done but please remember that it is rated for R19 inside an air tight closed cavity which is never the case in a crawl space. One side is always exposed to air. With the ability for air to travel directly through the insulation and sides of it, it's R value is drastically lowered in a crawl space. Most likely between R2-R5. Also if the crawl space has high humidity, mold will begin to grow on the fiberglass insulation and paper backing. Fiberglass insulation also collects moisture and begins to fall down due to the added weight of the moisture.
2) Spray Foam Insulation:
Spray foam insulation is an air tight and moisture resistant insulation so it does have great benefits over fiberglass insulation. The cons associated with spray foam insulation is that termites can travel through it undetected by the homeowner and it doesn't have a silver radiant barrier to reflect radiant heat back into the crawl space. Most applied spray foam insulation in a crawl space has very little fire resistance so it does catch fire quickly and off gases poisonous fumes in the process.
IT IS NEVER RECOMMENDED TO INSTALL SPRAY FOAM INSULATION UNDER YOUR SUBFLOOR. If you do this, any kind of plumbing leak whether it's small or large will begin to move water sideways on the flooring system instead of leaking straight down to the crawl space floor. So even the smallest plumbing leak can cause thousands of dollars in water damage.
3) Board Foam Insulation (2 inches thick):
2 Inch thick board foam insulation has a true R10 value for the foundation walls being air tight and moisture proof. Our board foam insulation has a termite treatment mixed right into the insulation itself. If termites crew through it they will die. The silver radiant barrier on the face of the insulation reflects up to 95% radiant heat back into the crawl space which does wonders in the winter time protecting cold air from contacting your plumbing pipes, duct work, and subfloor. Board foam insulation is fire resistant.
