I’m looking for some advice on the best way to insulate and drywall a cathedral/vaulted ceiling in our house.
The ceiling gets very hot, so I’d like to add insulation and then install drywall underneath. The house was built in the 1960s in Hawaii, and the existing construction is a little different from a typical newer house.
Here are the measurements:
- Existing ceiling beams/rafters: 5-3/16" thick
- Inside spacing between beams: approx 46-3/8"
- It’s a vaulted/cathedral ceiling with the existing beams exposed on the interior.
- There isn't a conventional framed attic space above it.
My main questions are:
What would be the best way to insulate this ceiling?
Should I frame between the existing beams with additional lumber to create cavities for insulation?
What type/thickness of insulation would you recommend for a hot Hawaii climate?
Would I need to leave an air channel/ventilation space between the insulation and the roof sheathing?
What would be the best way to attach drywall when the existing beams are spaced 46-3/8" apart?
Would you recommend adding furring strips/strapping across the bottom of the existing beams before hanging drywall?
I'm trying to do this correctly rather than just stuffing insulation between the beams and covering it up.
What would you do if this were your house? Any advice on the proper assembly, framing, insulation, vapor/air control, and drywall attachment would be greatly appreciated.