cathedral ceiling sweats

bethmc

We have a log home with a cathedral ceiling. The problem is it sweats when the temperatures are in the single digits and the sun pops out. Not only does it sweat but on the shed dormer, the pitch of the roof doesn't let the water drain, so it drips in the house into the loft, bedroom and bathroom. The ceiling is 2x6 tongue and groove, 3 1/2 " insulation panels with an R value of 18, 1 1/2" air space, plywood, felt then shingles. From what I gather we should have had a layer of felt put on between the 2x6 tongue and groove and the insulation. Well anyway, we are trying to solve this problem. From what I can find out, 1 way would be to remove the shingles, felt and plywood. Fill in the 1 1/2" air space with insulation, then install the plywood, felt and shingles so there would be no air space. Also, we have had a couple of contractors come out and they think that if we would leave the roof the way it is, install bubble wrap directly on the shingles, then put a metal roof on, this would also eliminate the problem and be less costly. Any thoughts on this as I would like to fix this once and not have to do it again!!!! Any help here would be greatly appreciated....thanks beth

OldNBroken

I sure hope you didn't seriously listen to those contractors.
From what you are describing, Your roofdeck is constructed correctly. This sounds like a bad ventilation issue to me.
As far as the low slope area, it sounds like it needs more attention. It should have a low-slope membrane instead of the shingles. Properly applied and running 2 feet up the transition to the steeper pitch, then the shingles on the steeper pitch should start over the top of that, just above the actual transition.

No, you should not need felt between your t&g and your insulation and, NO, you do not want to fill in your 1 1/2" void.
You need to have proper soffit ventilation AND proper ridge ventilation along with that 1 1/2" space. Without both, your roofdeck is not properly ventilated.

You never mentioned how old the roof is or what the pitches of the decks are. As long as it is in good shape, you shouldn't let anyone sell you a new roof. You need to find a contractor knowledgeable in proper roof ventilation to inspect it and go from there. Just because someone calls themself a roofer, does not mean they know anything about all aspects of a proper roof. There are wayyy too many shingle bangers out there, that's all they know is how to install shingles.

Ed the Roofer

A vapor barrier under the warm heated side of the insulation would have been appropriate, but not felt paper.

As ONB already stated, the problem lies in the ventilation flowage.

A properly Balanced Intake and Exhaust Ventilation system should be a part of the ceiling system, which is vaulted, but I do not know if there are rafters or if it is hung by beams.

Ed

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bethmc

We have beams that you can see in the house. The the ceiling and roof built as described before. We did have our ridge vent replaced earlier in the spring. The old one sat very close to the house with shingles over them. The new one sits up probably about 3". When you put your fingers in the vents under the overhang, you can feel the air flow and it feels like it is pulling well. We haven't gone thru another winter after the new ridge vent was installed. Maybe we should wait and see.....I just don't want another rain forest again (not quite that bad, but it seems like it is at the time)....thanks so much for both of your replies..beth

Ed the Roofer

So, it has not sweated the condensation since the newer Ridge Vent was installed?

I would wait and see too.

You may have solved your problems with that remediation work.

Ed

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