Expert: Michael Hughes - 2/24/2008

Question
We are building in SW Louisiana. I am considering poly urethene in the attic, our builder is against it  as would not be able to tell if roof was leaking. wouldn't 'ice and water shield' protect sufficiently.
The walls are 2x4 and builder claims he can get R-19 with blown fiberglass, from what I've read this is not possible unless we have 2x6 exterior framing. If necessary, how difficult would it be for my builder to do 2x6 versus 2x4 exterior framing? Thanks!

Answer
I prefer "insulsafe" blown insulation in the attic. The wall framing should not effect your attic insulation only your wall insulation. You can get up to R-15 in a 2x4 wall but R-15 is not a commodity item and is expensive.R-13 interior wall and an insulated sheathing on the exterior will get you an acceptable R value.
Ice and water guard are required if you are in a freeze thaw climate and you are not using a "cold roof" design (soffit and ridge vents).
You should not make a decision based on the possibility of a roof leak. New roofs should not leak for many years and probably never if the home is maintained.
I don't know if I have answered your question but I hope I have provided enough information.
Hope this helps.
M Hughes