R30 Rigid Insulation source
ScottShelley
| Posted in Energy, Heating & Insulation on
Hello,
I am looking for a good inexpensive source for R30 rigid insulation. I have a job here in California that calls for rigid insulation in a Cathedral ceiling framed with 2x8s. I am finding that it cost 4 times as much to have this insulation installed as opposed to Cathedral Batts. It would be less expensive for me to frame the roof with 2x10s and insulate it with regular insulation. I am however a little reluctant to do this, as the town we are working in is very particular about changing things on an approved set of plans. In some towns I work in I would not hesitate to do this…not here. Any good sources?
Replies
Best would be e.g. Thermax or similar polyisocyanurate. Best R-value per inch for the money, I think. R-7 per inch (aprox). You could easily get an R-35 in 6 inches leaving some ventilation above. It can be cut w/ a table saw accurately. If framing is really good, it can go in just fine. It is expensive, but you get what you pay for.
If space is not an issue and you aren't doing the framing, You could add to the framing. Or like you said, switch to a larger rafter ... but it would have to be 2x12s I think for the R-30 ... or go high density. A lot less effort. Some may say less affective, too, but we aren't talking a full blown attic w/ lots of free air flow. I used thick rigid insulation once where I felt I wanted every inch of space, but if you don't need it, you should be able to lose a few inches.
Consider at least asking the client for some latitude, but otherwise get the good rigid and have at it!
Edited 4/7/2009 9:53 pm ET by Clewless1