Quoted:
Quoted:
Quoted:
Quoted:
How big of an area? Square footage?
ETA:
Just saw your last post. With closed cell foam, you need at least 1" for it to be a vapor barrier. 2" if you are worried about exposure to moisture, which you should be since it's under a house.
I would highly recommend you get a quote from a pro. They should be around $1.80/ sqft for the first inch, then $.10-.30 after that for every additional inch. This varies alot from region to region. Just a guideline.
We dont know what moisture is here, in another environment I would be worried about moisture, but not here.
Trust me. You want 2". This is what I do.
I understand, I was in construction for most of my life. 2" would be the best, 1" would be the minimum, but 1/2 to 3/4 would probably accomplish what I want. Are you saying the foam is going to wick up moisture and hold it against the wood if I go less than 2". I have been under my house in all our weather cycles and I have never seen a hint of anything but bone dry powdery dust, I have been under many houses, in many parts of the country, none like it is here. If it will wick and trap moisture I will re think as we could get in a wet cycle for 4-5 years and this could become a concern.
Anything less than a full 1" of closed foam can't be classified as a vapor barrier. Whatever humidity you do experience can penetrate the foam over time, and it will hold it there for a while.
At 2", you can call it a moisture barrier, though you can't use it for submerged applications. They do make foams for that though.
What sets foam apart from other insulations is the foams ability to stop air/vapor from passing through floor boards, walls, roof. If you don't put at least 1", you may as well use batts.
The reason I recomend 2", is because no matter how good the applicator is, you will have some low spots; especially since he is spraying overhead.
The extra 1" is insurance, and extra insulation. If you go to a reputable installer, the extra inch should only be a few cents/ft more.