Choosing Between Two Roof Assemblies
Hi. I am in zone 4a (Nashville area).
I would appreciate a sanity check on my shop building/in-law suite building. (Pic below)
- If I go with the polyiso over the roof, how do I install it?
- Do seams need to be taped?
- What goes on bottom layer and what goes on top layer?
- My 2″ thick polyiso has a white skin on it. (Pic below)
- My 1.5″ polyiso has a black felt (Pic below)
- Is it foolish to only have 3.5″ of foam and I should go with vented attic and blow in cellulose?
I am weighing two roof assembly options:
- Blow-in cellulose over ceiling with vented attic
- 3.5″ Polyiso on top of OSB
I have the recycled polyiso on hand. The cellulose will be about $1400 (very affordable)
The polyiso route will give me a much more spacious feeling with 5 extra feet of space to peak. The trusses are 8ft OC (post frame).
The cellulose will give me a much higher R-Value
I will be making a pretty air tight assembly. Sealing with 3M 8067 and Dymonic 100.
I also have 2″ of recycled Fomular 250 25psi foam board under concrete.
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