1-year-old home with a low-slope shed-style roof: Lots of condensation is leaking in during cold snaps
Hello all, what a great website this is. So much useful information. We had our 2 story about 3000 sf home built in Ontario. Moved in Jan 2018. We have a low slope (4/12 i think) shed style roof. Its a simple roof its just one big low sloping roof with 2×12 roof rafters, plywood sheating, water and Ice membrane, greyish/bluish shingles. Interior 2nd floors ceilings start at about 7 feet at one side of the house and end up at about 14 feet at the other end of the house. We have an HRV system. 2018 no condensation issues or at least none that I could see in the ceilings. this winter Jan 2019, after a recent cold snap (ie it was -30 c or so outside then went down to above 0 over a day or 2), in multiple areas I could water leaking through the ceiling. About 5 different areas of the 2nd floor ceiling. 2 of the areas where around pot lights in the 2nd floor ceiling. (yes My builder put leaking non airtight pot lights in the 2nd floor ceiling just below the attic). 99% sure its not a leaky roof its condensation. Leading up to this, I had the humidifier cranked so high, all my windows had ALOT of condensation on them. My mistake Fast forward to the next cold snap, again temps went down to -30 c then above 0 again and again, there were leaks in the same spots as well as a few new ones. And this time, it sounded like it was raining all over my ceilings. I thought it was raining outside, I looked out and saw NO RAIN and stepped out and there was no rain. The attic space has R31 batt insulation, and then maybe 2 -3 inches of baffles from soffit to soffit for “ventilation”. And thats it. So now, my builder is prosposing we rip off the entire 2nd floor ceiling, get rid of everything (ie drywall, insulation and baffles) and make it an unvented attic with closed cell spray. Ive done a lot of research and now I see that low slope/crammed attic style roof are notoriously difficult to insulate and ventilate. i just want to know if theres anything majorly wrong with unventilated attics. I know shingles will cook off faster but I mean low slope roofs barely ventilate properly anyway. Pls advise!!
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