I have a 18 x 20 foot crawl space under an addition next to unfinished full basement space. The crawl space is unheated and I want to insulate the floor and walls so that the addition above it stays warmer. The crawl space walls are cement block, and the floor is concrete poured over a vapor barrier. Based on some articles I read, I am going to close off the 2 small block vents and insulate the walls and joists. I can access the crawl space through a 3 x 2 foot pass-through into the full basement, which I use as a workshop. The basement has 2 dehumidifiers. I plan on keeping the access to the craw space open for wood and material storage.
Here is my question: I planned on using 2″ (Blue) foam panels for the walls, which are 2- 3 feet high and above ground. Do I need to put a vapor barrier between the walls and the foam board? The walls are not wet or damp, but the outside is exposed to the rain and weather.
Thanks in advance for any advice.
Replies
I had the same situation when I purchased my current house. I considered your solution strongly but ended up calling a insulation contractor to spray the walls with foam. It cost a little more but saved a lot of aggravation and tightened up the crawl space nicely. I then installed batts in the floor.
I don't believe a vapor barrier is necessary between the foam and the board unless you anticipate a moisture problem, and that would already be obvious IMO.
Doesn't foam require something fireproof over it???Bud
Not quite sure I understand. In a crawlspace? Yes it is required to be covered in a mechanical room or living space but not so sure about a crawlspace. I was told by the BI that it wasn't, but they have provided misguided info in the past.
I was not saying that it did need to be covered. Just a question,
because I originally thought it needed to be covered,and was asking for my own reference...I am considering the same thing as the OP..
Bud
Just did a crawl space where the BI was wanting firerock over the icynene.Our installer satified the requirement by spraying a coat of FireFree88 over the icynene as an ignition barrier
Barry E-Remodeler
In a living space, yes.
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Edited 7/17/2007 5:27 pm ET by Piffin
Here, also required in a crawlspacethough some may live there
Barry E-Remodeler
I do this all the time. Around here, (Detroit area) were required to run the rigid above grade, and cover that with 1/2" drywall for a fire barrier.
If I were you I would not insulate the floor. Just run a couple of heats in there. Treat it like a basement.
Insulation between the two areas would only (maybe) keep the crawl space a little quieter. Essentially you'd be insulating between two conditioned areas.
That type of foam IS a VB so no you don't need another.
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I agree with MSA1, insulate the above grade walls, close off vents and forget about insulation in the floor. Basically what you have is a short basement. As far as fire code our building department requires a fire resistive barrier over the foam, or maybe look at alternate insulation types. I have seen the encapsulated batts, but installation is a mess, have to secure somehow to the top of the wall on the plate and they hang down and look like a mess.