Curious if anyone’s actually measured attic temps before and after adding vents? I’ve always wondered if the difference is as dramatic as people hope. Also, has anyone had issues with blown-in insulation blocking soffit vents over time? That’s tripped me up more than once...
has anyone had issues with blown-in insulation blocking soffit vents over time? That’s tripped me up more than once...
Yeah, that’s a big one. I’ve had to go back up there with a flashlight and a broom handle more than once because the insulation crept over the baffles. I measured attic temps before and after adding two extra roof vents—went from 140°F down to about 120°F on a hot day. Not as dramatic as I hoped, but it did help with the musty smell and shingle curling. Anyone else notice that blown-in stuff just migrates no matter how careful you are?
Anyone else notice that blown-in stuff just migrates no matter how careful you are?
Yeah, I’ve run into that too. Even with baffles in place, it’s like the insulation has a mind of its own—especially after a few years and a couple of windy storms. I’ve tried stapling mesh along the rafters near the soffits, but honestly, it’s not 100%. The migration slows down, but doesn’t totally stop.
Your attic temps dropping by 20°F is actually pretty solid, even if it’s not as dramatic as you hoped. In my experience, once you get below about 120°F up there, you start seeing less shingle damage and fewer weird smells. I do wonder if some of those musty odors are just from old insulation holding moisture, not just heat.
One thing I’ve noticed—if you’re in a humid area, even minor vent blockages can make a big difference. I’m in the Midwest and sometimes just clearing out a handful of blocked soffits made more impact than adding another roof vent. It’s a constant battle, but worth it for roof life and indoor air quality.
Funny how the insulation always finds a way to sneak where it shouldn’t, right? I’ve got cellulose up there and it’s like it’s got legs—one good windstorm and suddenly the soffit vents are half buried again. I tried using that mesh too, but after crawling around in the attic and sweating buckets, I’m not convinced it’s a perfect fix. It definitely helps, but like you said, it’s not foolproof.
You’re spot on about attic temps. I used to obsess over getting it as cool as possible, but after a while I realized that just keeping it under 120°F makes a noticeable difference for the shingles and the weird attic funk. I’d get that musty smell every August, and it turned out to be old insulation that’d soaked up some moisture after a roof leak a few years back. Pulled out the worst of it, tossed in a few bags of fresh stuff, and the smell improved a ton.
The vent thing is wild. I’m in Ohio, and the humidity here is no joke in summer. I thought adding more roof vents would be the answer, but honestly, just making sure the soffits weren’t blocked by insulation or bird nests did more than I expected. It’s not glamorous work, but those little blockages add up fast. Once I cleared them, the attic felt less like a sauna and more like... well, still hot, but not “bake your tools” hot.
One thing I don’t totally agree on—I’ve seen some folks swear by those powered attic fans, but for me they just pulled conditioned air from the house and made things worse. Passive airflow plus good insulation seems to be the sweet spot for my setup. Every house is different though, and sometimes you just have to tinker until you find what works.
Anyway, it’s always something with attics. I swear, if I ever build again, I’m going with spray foam and skipping the blown-in circus altogether...
I’ve got cellulose up there and it’s like it’s got legs—one good windstorm and suddenly the soffit vents are half buried again.
That made me laugh—mine does the same, like it’s migrating south for the winter. I’ve tried those cardboard baffles, but they end up looking like a toddler put them in after a few months. I’m with you on the powered attic fans. Tried one, and my AC bills went up. Passive airflow just seems more reliable, even if it means crawling around up there every spring. If I ever win the lottery, spray foam all the way...