I get the appeal of breathable membranes, but I’m still a little skeptical about skipping peel-and-stick, especially in places with wild storms. When we bought our house last year (asphalt shingles, low slope, Midwest), the inspector pointed out a few spots where wind-driven rain had snuck under the old felt. The roofer we hired swore by peel-and-stick for the eaves and valleys, said it’s the only thing that really holds up when ice dams hit. Maybe it’s not perfect for the whole roof, but I’d be nervous relying just on a vapor-open layer in our climate. Anyone else feel like the “let it breathe” approach could backfire if you get a big leak?
If underlayments had a race, felt would probably trip over its own shoelaces halfway through and breathable membranes would be jogging with a fancy water bottle, while peel-and-stick is just stubbornly crawling over the finish line with duct tape on its knees. That’s how it feels in the Midwest anyway.
I get the anxiety about skipping peel-and-stick, especially after seeing what ice dams can do. I’ve patched up more than a few attics where water found its way in through supposed “bulletproof” layers. But here’s the thing—I’ve also seen peel-and-stick turn into a sticky nightmare when someone needed to do repairs down the road. Ever tried prying that stuff off plywood after five years? It’s like wrestling a roll of chewing gum in July.
The “let it breathe” crowd does have a point, though. Last spring I was called out to a place where they’d gone heavy on peel-and-stick everywhere, and sure, no leaks from above... but the attic was sweating like a gym sock. Mold on every rafter. Turns out, trapping all that moisture inside can backfire if your house isn’t vented just right or you’ve got sneaky humidity from below.
Honestly, I’m not convinced there’s a one-size-fits-all answer. My own place (asphalt shingles, 4/12 pitch, Indiana) has peel-and-stick in the valleys and eaves—because yes, those are always trouble spots—but I went with synthetic underlayment for the rest. Breathable enough to keep things dry underneath, but not so open that rain gets ideas.
If you’re in tornado alley or somewhere with wild freeze-thaw cycles, maybe belt and suspenders makes sense: peel-and-stick where it counts, something lighter everywhere else. Just don’t let anyone tell you their way is foolproof. Water always finds a way... usually at 3am during the worst thunderstorm of the year.
That’s a pretty solid breakdown—had me laughing with the chewing gum in July bit. I’ve been on both sides of this, too. When I re-roofed my place (old Cape Cod, Michigan), I was totally convinced peel-and-stick was the only way to go for the whole thing. Figured if a little is good, more’s gotta be better, right? Well, fast forward a few years and I had to swap out a vent. That stuff did NOT want to let go. Ended up gouging the plywood in a couple spots just trying to get it off. My neighbor came over and just shook his head. “Told you so,” was all he said.
On the flip side, my brother went with just synthetic underlayment on his place (ranch style, also Michigan but a bit further north), and he’s had a couple leaks around the chimney after some ice damming last winter. Not catastrophic, but enough to stain the ceiling and make him wish he’d done peel-and-stick at least in that area.
I’m starting to think the mix-and-match approach is the sweet spot, like you mentioned. Use the sticky stuff where the water’s most likely to sneak in—valleys, eaves, around chimneys—and then the lighter, breathable stuff everywhere else. Seems like a good compromise between future repair headaches and keeping the attic from turning into a sauna.
I’m curious if anyone’s had luck with those newer “hybrid” underlayments? I keep seeing ads for ones that claim to be self-sealing but also breathable. Sounds almost too good to be true. Anyone actually tried them, or is it just marketing hype?
And on the venting thing—how do you all keep your attics dry when you’ve got a lot of peel-and-stick? I added a ridge vent and more soffit vents, but I still get a bit of condensation when it swings from cold to warm real fast. Maybe it’s just the joys of Midwest weather...
Tried one of those hybrid underlayments last year on a detached garage—brand claimed it was both self-sealing and “vapor open.” Honestly, install was easy, but I’m not convinced it’s much different from high-end synthetics. No leaks yet, but time will tell. As for attic moisture, even with more vents, I still get some frost on the nails during those wild Michigan temp swings. Just seems like part of the deal here.
