Home>Discussions>INSULATION & HVAC>Moisture Problems in Crawl Space: Is Spray Foam a fix?
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Moisture Problems in Crawl Space: Is Spray Foam a fix?

I'm in the process of fixing up an old 1880's stage coach house that suffered severe fire damage two years ago and sat vacant since then. As a result of the fire fighting efforts the house also sustained significant water damage to the basement and i'm still working to remedy these issues.

The basement is 3 courses brick on the north face and wet set stone for the other three (approximately 21" thick) the first step in renovating was completely gutting the old basement down to the foundation, reframing with 2x6 and spray foaming (2") then insulating / drywall. The north face of the foundation is above grade but the rest are below and it seemed much of the moisture at the time was due to condensation on the walls. Since then i am still noticing a lot of moisture coming in through the floor, the previous owner had dug out a crawlspace under the house to install supports and help deal with the moisture problem pre fire.

I have two 600SF foam kits left from doing the basement and i'm wondering if my best bet is to spray foam the entire ceiling of the crawl space. If so do i have to worry about moisture being trapped between the spray foam and the floor joists / supports?

I have also heard i should spray foam all the walls of the crawl space but not the ceiling.

What is the best way to go in terms of efficiency / moisture??

Any advice would be greatly appreciated!

Re: Moisture Problems in Crawl Space: Is Spray Foam a fix?

How's the ventilation in the crawl space? In my city, a crawl space must have unobstruced vent openings.

Re: Moisture Problems in Crawl Space: Is Spray Foam a fix?

That's right, In most cities you must have venting. If not, then you may get your exact problem. It is also average to have older homes without venting. Is it a granite or field stone foundation? It could be easy to add venting.

Re: Moisture Problems in Crawl Space: Is Spray Foam a fix?

The spray foam wouldn't trap moisture in the wood. IT would dry to the inside of the home and reach equilibrium with indoor humidity levels.

You will still want to vent the crawlspace wince the ground is probably dirt. and you have stone and brick walls. To hard to completely seal it up. SO sealing under the floor is a good idea.

Re: Moisture Problems in Crawl Space: Is Spray Foam a fix?

Thanks for the replies, the crawl space has four 3"x12" vent holes around the perimeter, in addition it seems like the old owner was in the process of installing a blower to help with air circulation.

I was told by a local contractor that i want the vent holes open in the winter and blocked in the summer unless i was going to force some air movement. It seems the previous owner was running dehumidifiers in the crawlspace 24/7 and never had the power hooked up to the blower.

Would my best bet be to spray foam the ceiling of the crawlspace and run the blower with the vent holes open.

Thanks for all the replies!

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