Floor and ceiling

bpress54 · 11-12-2012, 04:51 PM

I just purchased a bungalow that was used as a summer residence. The previous owner insulated the walls, but the ceiling is open rafters with 1x6 tongue and groove plank roofing (under tar paper and shingles) and has no insulation at all. The building is on a crawl space that is only about a foot high and for all intents and purposes, is inaccessible. I want to convert this to a year round residence and I'm thinking of using rigid foam insulation between the rafters to insulate the ceiling, but I don't know what to do about the floor, short of ripping it up to install insulation, which I'd rather not do. Does anyone have any suggestions? I live in New Jersey so it does get fairly cold here in the winter.

funfool · 11-12-2012, 05:36 PM

rigid foam is good for some situations.
Problem is, only get about r-7 from it.
If your rafters are at least 2x4, rolled fiberglass will give you r-13.
2x6 rafter you can get r-19.
You want to get as much r value as you can, and rigid foam is not cheap.

joecaption · 11-12-2012, 05:43 PM

Most heat is lost out the windows and doors, next would be the walls and ceiling, last would be the floors.

Windows on Wash · 11-13-2012, 09:52 AM

Quote:

Originally Posted by funfool

rigid foam is good for some situations.
Problem is, only get about r-7 from it.
If your rafters are at least 2x4, rolled fiberglass will give you r-13.
2x6 rafter you can get r-19.
You want to get as much r value as you can, and rigid foam is not cheap.

Rigid foam gets you and R-7 per inch in some cases. The R-13 you are referencing is from 3.5" of fiberglass that also has no air barrier aspect or moisture barrier (if unfaced).

The best and easiest thing (usually equals the most expensive as well) would be to condition the crawl and spray foam the stem walls and the inside of the roof with CC SPF.

Vapor barrier and insulation layer in on shot.

You will still have cold rafters and they will be condensation locations but you could cover the rafters with a rigid foam and drywall the ceiling if you have already sprayed the rafters with foam.

bpress54 · 11-13-2012, 11:53 AM

What do you mean by "condition the crawl space?" And what is a stem wall? I'm not familiar with that term. Thanks

Windows on Wash · 11-13-2012, 12:56 PM

If you search this forum, you will find a ton of threads on crawlspaces.