First, let me ask...along with installing foam insulation, what are you going to do to solve the moisture issue in your crawl space?
Spray foam insulation on the sub-floor does not address the main issue in a crawl space- moisture from the dirt beneath the home. The wood members in the crawl space will still be exposed to ground moisture. There are only two primary ingredients needed for rot and mold to thrive: one is organic material, like the wood beneath a home, and the second is water. Replacing the wood in a house is practically impossible, and very costly. So, the only avenue to preventing structural damage and those musty smells is to eliminate the moisture by installing a CleanSpace Encapsulation System.
A local spray foam contractor recently told me that they had a previous job in which the foam insulation that was applied to the subfloor actually locked in the moisture in the crawl space and created a bigger moisture and mold problem in the crawl space. Not the outcome they expected!
_______________________________________
Second... foam insulation applied on the subfloor renders the wood members unaccessible or "no longer visible" for an inspection.
Some pest control companies will void your termite warranty if the sub-floor wood is no longer accessible or visible for an inspection. Check with your pest control company before choosing this option. (With the CleanSpace system, our liner is installed a minimum of 3" down from the top of the wall so that termites cannot get into the framing without being seen.)I recently spoke with a customer that stated her friend had her house inspected for a pending sale. She was requested to cut out and remove some of the foam insulation so the home inspector could visually inspect the sub-floor wood members in the crawl space WOW! I bet that customer didn't plan on spending all that money to foam insulate their crawl space and to later cut it out. Ouch!
A more effective approach to spray foam insulation is to insulate the foundation walls, rather than the sub-floor, provided a proper encapsulation system has been installed.
As stated on the U.S. Department of Energy's website, to effectively insulate your crawl space for energy efficiency and to create a comfortable home, you need to properly control moisture in your crawl space.
Our goal at Clean USA is to fix your damp dirt crawl space...FOR GOOD!