Cathedral ceiling and ridge vents
I have a variant of what seems to be common questions about cathedral ceilings. I’m new to the site and tried to research as much as I could. My plan is to air seal the rafter bays – the 4 electrical boxes, 1 plumbing vent, caulking all wood-to-wood joints, reinforcing any tape joints I see in the plastic plus run a bead of open cell foam along the plastic sheet and rafter to air seal if any joints on the rafter, insulate the top plate with rigid insulation (which will also cover any missing sheathing), and install a soffit baffle using rigid insulation (about 1 to 1.5” gap). In the attic area, there are 4 fans and 2 recessed lights plus the chimney to air seal around and of course check the plastic.
Am I missing anything? Should I change our gable vent to a ridge vent? If so, what kind? I’ve read about baffled ridge vents – are they preferred? Ridge vents are new for me as always used other kinds. Should I add a ridge vent to the part of the house with no upper vents?
I live in Lansing, NY (climate zone 6). We have a ranch built in 1992 with a loft and partial cathedral ceilings (12’ from the eave to a flat section that is 8’ across). Our current profile is tongue & groove ceiling, plastic sheeting, and unfaced fiberglass insulation in the 2×8 rafters (guessing R19). The shingles are due for replacement, so am trying to take care of some of our air leakage. There is no attic access so I will remove some roof decking (well, probably most – one at a time) to get access. No evidence of moisture problems.
Current ventilation is soffits vents and gable end vents (the vinyl siding is louvered but I haven’t made it up to look at them yet) in the main part of the house (with a loft). The baffles looked positioned more to force air through the fiberglass than to keep it next to the decking. There are soffit vents, but no roof vents in the shorter part of the house (living room over the garage). We hear a lot of popping (assuming the truss) from this attic space when the temps get real cold.
I have looked in some of the soffit vents and removed a half sheet of roof decking to get a peak at what was inside. Found out our cold wall had sheathing installed 1.5” short of the top plate, so that is likely the cause of our air moving straight in from outside where it goes in the soffit vent and down the wall instead of up the rafter bay.
Not going to do anything with the ceiling, am going to avoid adding insulation above the rafters which will affect the skylights, and can’t afford to spray foam everything right now.
I have read several articles on here about cathedral ceilings and air sealing. I know I will be short on insulation in the rafter bays – should be about R25. So there will be some heat going to the roof deck, but I haven’t seen evidence of ice dams but our roof is clear of snow relatively quickly. I will add insulation to the flat area to ensure we are at least the R49.
Sorry for the length of the details. Thanks for your input.
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