Closed Cell In My Unvented Gable Roof 5.5 in or 4 in To Save Money???
My name is Hazen and I’m going through the motions on a new construction build of a mini home on trailer. The home will be in Washington state climate zone 5. I’ve 99% decided to have a local spray foam contractor put in closed cell in the 2×6 unvented ceiling rafters after pondering flash and batt. Walls are rockwool. Floor is rockwool and foamular.
4in quoted at $1,350 R28
5.5in quoted at $2,050 R38
Is the money savings worth going down to 4in? R38 is code, but then again, it’s rare that a tiny house ever has R38 in the roof, whether below or above the sheathing, because of height and weight restrictions.
I’ll hang 1/4in drywall after to seal out inside air and then finish with some wood t & g of some kind.
On the other side of my roof is OSB, titanium PSU 30 ice and water shield, standing seam metal.
4in of closed cell will do the trick to prevent condensation yeah?
Thanks for feedback.
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