I'm looking for suggestions about how to upgrade a vented cathedral ceiling covered with very nicely finished (albeit leaky) tongue and groove pine. Some specifics:
About 1/2 the assembly is vented from eave to ridge. The other 1/2 is tied into an accessible attic flat. Presumably, the 14" TJI's have poorly installed styrofoam proper vents. I don't believe they go all the way to the ridge and are not air sealed at all.
The 14" TJI is insulated with faced FGB (12"). The facing is installed to the warm side of the home.
There is a metal roof and the customer has no intention (or budget) to remove it and install rigid on the roof.
The tongue and groove is finished nicely with several coats of clear coat. It's a high end home and this assembly needs to be put back together perfectly.
The ceiling is peppered with recessed lights.
Each slope is 14' long and the room is 26' long.
I've noodled around with a few options based on the customer's budget and what we're hoping to achieve. They run the gamut from removing the T&G and FGB, installing sheetrock as an air barrier, dense packing the cavity, and re-installing the T&G. The ridge and eaves would be blocked and we'd have a hot roof. Moisture load in the home in low and managed.
Another option was to access the eave and ridge and 2 other area but removing strips of T&G. We'd then remove the FGB, block eaves and ridge, install 1" of CCF on the back side of the T&G (as an air barrier) and dense pack the cavity with cell. Might trap moisture, though?
How about removing sections of the T&G, removing FGB, and adding 3" of CCF to the underside of the roof then dense packing and re-installing T&G? Not a perfect air barrier but the likelihood of condensation is reduced from the foam.
Straight up dense pack the assembly? Just block the soffits/ ridge and keep the FGB?
I think creating a hot roof makes sense as it would be challenging to install a continuous vent from eave to ridge.
Like all T&G, the corners are leakiest although in this assembly, it was all leaky during my BD test.
Tongue and groove cathedrals without a proper air barrier (and poorly/ incorrectly vented) are a bugger! If anyone has any ideas on a reasonable way to make this assembly perform better, I'm open to suggestions.