Another roof assembly question
I am building a 10′ x 28′ house on a trailer. Steel 2×4 framing, 16 on center in both the walls and roof panel. I’m in C zone 3 which calls for R-30 in the ceiling which I’m assuming includes the roof assembly. With the height restrictions at 14′ I have little room on top. This is a shed roof, minimum pitch.
The architect suggests the following:
Inside to outside
1. 1/2″ (min) gypboard
2. 3 1/2 CFS Framing with Rockwool between joists . (R13)
3. 9/16 verco shallow decking 26 g.
4. 2″ rigid insulation (R10)
5. Waterproof membrane underlayment
It’s obvious that I could increase the R value by adding more rigid insulation on top but I’d rather not. If anyone has some brilliant workaround solution for increasing the r value, I’d love to hear it!
Also, will I need a vapor barrier somewhere in the roof assembly or is the membrane on top sufficient?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part