Man, I hear you on the double felt mess. Had a crew try that on one of my rentals a few years back—looked fine until we had a week of rain and then it was like peeling off a sticky fruit roll-up. Decking was stained, smelled weird, and the tenants kept asking if something died in the attic. I’m all for extra protection, but honestly, synthetic’s been way less drama for me. And yeah, ventilation’s the unsung hero... learned that the hard way after a summer with attic temps hotter than my grill.
Interesting—I've actually had the opposite experience with synthetic. Maybe it's just my area (humid summers, lots of storms), but I found the synthetic stuff got a little too slick for the roofers and a couple seams ended up letting water in during install. Ever try one of those heavier felts, like 30#? I know it's old school, but it seemed to hold up better for me during a long rainy stretch. Curious if anyone else has had issues with synthetic wrinkling or shifting before shingles go on... or maybe I just had a bad batch.
Curious if anyone else has had issues with synthetic wrinkling or shifting before shingles go on...
Yeah, I’ve definitely seen synthetic wrinkle up when it’s humid and the sun comes out right after a storm. I’m in the southeast, so it’s a constant battle with moisture. The heavier 30# felt always seemed to stay put better for me too, especially if there was any delay before the shingles went down. Only downside is it’s heavier to lug up the ladder, but I’ll take that over leaks any day. Maybe it’s just one of those “depends on your weather” things...
- Noticed synthetic underlayment gets wavy here too, especially if it sits more than a day or two before shingles go on.
- Seen it lift at the seams after a windy night—makes me wonder how much it’s really helping if there’s a delay.
- Felt is heavier, yeah, but at least it doesn’t look like a potato chip after a hot afternoon.
- I still check for staples or fasteners every time… some crews get lazy and that’s when things go sideways.
- Maybe I’m old school, but I trust the old felt more than most of these new synthetics. Just my two cents.
I’ve run into the same thing with synthetics curling and lifting, especially when there’s a gap between install and shingles. Did an inspection last month—brand new roof, but the underlayment had been on for three days during a stretch of windy, humid weather. By the time the crew got back, half the seams had bubbled up and there were spots where it looked like the stuff just wanted to peel itself right off. Not the best look for something that’s supposed to be the “improvement” over felt.
Felt isn’t perfect, but I’ll admit I see fewer issues with it going wavy or tearing if it’s properly fastened. It’s heavier, sure, but that actually seems to help in those early days before the shingles go on. I’ve also noticed some synthetics are super slippery—almost wiped out once just trying to get a closer look at a vent pipe. Never had that problem with old-school felt.
One thing I do see a lot is crews skimping on fasteners with synthetic. Maybe because they think it’s lighter and doesn’t need as many? Either way, I end up flagging a lot of loose seams or spots where water could sneak in if there’s a delay. It’s not always about the material—sometimes it’s just how carefully (or not) it gets put down.
I get why people like synthetic—lighter rolls, easier to handle, doesn’t tear as easy when you’re walking on it. But honestly, I’m with you: if there’s any chance of weather rolling in before the shingles are on, I’d rather see felt up there. At least until someone invents a synthetic that actually stays put in real-world conditions...
