How to stop a Cathedral ceiling from sweating
Newly constructed home in upstate New York (Cold Climate) with cathedral ceilings throughout. R38 paper faced batts with Sheetrock and T&G pine cover the entire ceiling. After the long winter months have past the warmer weather causes water to come streaming down the inside of the valleys and down the walls for at least 5-6 hours. A roofing contractor said it was caused by ice damning so I replaced the shingles, s&i guard etc. in both valleys and I had a leak this past Sunday afternoon (no rain or snow). I don't know what to do besides rip down the ceiling and spray foam. Would a bad insulating job at or near the valley allow enough water diffusion to cause this kind of leak? I also have can lights which may be contributing to the problem, however, I have known leaks above and beyond the lights. In the one spot where I was able to access the bottom of the roof sheathing it was wet in both cavities. On average the RH in the peak is between 45% and 55%, a little high but I don't think it is the cause.
I also installed styrofoam baffle vents in the valleys from the ridge to the LVL valley rafter, which if anything is probably hurting the situation but I really don't know.
I'm beside myself, if anyone can help it would be greatly appreciated.
Posted Dec 6, 2011 10:39 AM ET
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