Air sealing sheathing around dormer window
tjones1014
| Posted in General Questions on
CZ 3A/4A (N GA area)
2001 gut reno
We have a dormer window in our upstairs bonus room, and I’m not sure what to do where the roof sheathing meets the angled wall sheathing around the dormer window (circled in red).
Do I need to caulk? Tape? Leave it be?
I included a closeup pic as well
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Replies
It is hard to tell from the photo if the light-colored spot is day light, then you have a flashing\roofing problem if the light spot is the shiny back of the metal flashing that would be normal.
Your “bonus room” makes your home a half story building with cathedral ceilings. Yours is one of the few times I think closed cell spray foam is a good idea. Mostly because air sealing half story building is a nightmare at best and the sloped ceiling leave you so little space for the required R38 insulation foam is almost the only way to fit it in.
https://www.greenbuildingadvisor.com/article/insulating-a-cape-cod-house
https://www.greenbuildingadvisor.com/article/five-cathedral-ceilings-that-work
Walta
The light spot is the metal flashing.
We won't be going the spray foam route.
Do I need to air seal that gap on the interior where the flashing is showing?
tjones,
That's not great. The roofing underlayment should run up the wall so the flashing should not be visible.
Any help with what we can do as it is would be greatly appreciated! The roof was not replaced, as it's still in good shape overall.
tjones,
Tape the joint as you are doing with other gaps in the exterior sheathing.
Tape from the interior?
tjones,
The interior is the only place you have access to.
Correct. I just wanted to be sure we were on the same page. Thanks!
On the taping subject, is it worth it to tape small sections of the top plate that I can reach? We caulked the tops of the stud bays and down 6" on each side like you suggested in a previous post, since we couldn't reach from the exterior. I can touch the top of the OSB within each roof rafters bay, but it would only be in those small reachable sections. Is it worth it to tape what I can, or is it diminishing returns at this point since the interior portion is caulked?