EPS/XPS or ??? on interior side of cathedral roof in zone 7
I have a vented R40 cathedral ceiling (parallel scissor truss). It currently has two layers of R20 fiberglass batt insulation above the drywall. I would like to add some insulation; the only option is to add it to the interior..
Can I do this and if so how much EPS/or XPS or ??? can I add? I have room to add 6 inches of rigid foam or similar.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part