Hi All,

I am in the process of re-modeling the 3rd story of a home in Oregon (zone 4 or 5). I opened the ceiling to create a cathedral ceiling. I have never insulated a cathedral roof so I have spent a few weeks reviewing all the post here and think I have the solution, but I would like some input if possible. First of all, there may be better solutions, such as spray foam, but budget constraints dictate the need for coming up with a workable and affordable solution.

The rook wad framed with 2x8s so I added 2×4 cross braces (strapping) to add depth and to even out the ceiling, which was off by as much as 1/2 an inch from rafter to rafter. I decided to go with a vented roof versus a hot roof even though it will be difficult at best. There are soffit vents on the two long sides, but not on the short sides. I plan on adding a ridge vent later this year. I am thinking that the best way to help ventilation in the cavities with soffit or ridge vent access is to drill 1″ holes to increase air flow from the vented cavities. Any better ideas?

As for the insulation, I was thinking of doing a ventilation chute, R 30 rock wool, 1″ XPS, strapping, and then drywall. I would have to notch the rock wool to fit around the 2×4 strapping, which will be time consuming since they are placed 12″ apart.

Is there anything that I am missing or could do better within a reasonable budget? I have considered dense cellulose, but I have never done it before and I’m a little worried that I may not be able to achieve the needed density or leave part of the cavity open by mistake. Thanks in advance for the advice!