Need roofing ventilation advice


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Old 04-07-23, 03:48 PM
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Need roofing ventilation advice

We have a cape code home built in the late 1980s with a lofted cathedral ceiling on one half of the house and one upstairs bedroom. Our roof rafters do not have baffles, wasnt code at the time, and are basically stuffed with insulation all the way to the roof sheathing. (only one area on the back of the house where there is an upstairs bedroom was retrofitted with baffles where, when getting new shingles 17 years ago, wet plywood was discovered. That was baffled, new insulation installed with new sheathing and that was resolved). Anyways, the rest of the entire house, cathedral ceiling and front of house with front porch again, no baffles and packed insulation. Someone once said it was so hot and dry it smelled like kindling wood. Weve not noticed any moisture or wet areas on the ceiling or plywood, but the insulation is filthy dirty, especially in the front area where the porch runs across the house and cathedral ceiling attic section, it smells awful, and when it gets hot outside or the sun shines, the entire house smells like hot wood and dirty insulation. So, fast forward to now, we are scheduled to get another new shingle job done due to getting cosmetically defective shingles (warranty covered) a couple of years ago and I spoke to the roofer about the lack of air flow and hit wood smell backing up in the house. He said they would basically have to pull all the plywood off, all the old insulation out, re-insulate, install baffles, then reroof. He said it would help alleviate the smell but after 30+ years, probably not totally stop it. Its either that, or he said fix it from the inside by ripping all the Sheetrock out and then doing everything from the inside. (As a side note, when the roof was reshingled a couple of years ago, all the plywood was fine. So, my question is, is it worth it to replace the old insulation and get more air flowing?
 
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Old 04-07-23, 04:09 PM
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You would be reducing R value if you reduce the amount of insulation just for the sake of ventilation. More ventilation but a colder ceiling. So no, I would not do it. For cathedral ceilings the best thing to do is tackle it from the inside with closed cell spray foam. You'd remove the drywall someday, remove your insulation and get it professionally spray foamed.
 
 

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