Totally get what you mean about sliding around—had a guy nearly end up in the neighbor’s yard trying to lay peel-and-stick on a 10/12 in July. I’ll take synthetic any day, especially after seeing how felt just turns into mush after a couple storms. Cap nails are annoying, but man, at least you know it’s not going anywhere when the wind picks up.
Had a similar situation last summer—steep pitch, mid-July, and the felt just wouldn’t stay put. Guys were slipping all over the place, and by the time we finished, half of it was already wrinkling up. Switched to synthetic after that and haven’t looked back. Yeah, cap nails slow things down a bit, but I’ll take that over having to redo the whole underlayment after a windy night. Felt just doesn’t hold up in this climate, not worth the hassle.
I get where you’re coming from with felt, but I’ve actually had better luck with it than synthetic in a few cases. On my garage roof (pretty steep, northeast), the heavier 30 lb felt held up fine for a week before shingles—no wrinkles or blow-offs. Maybe it’s just luck, or maybe the way it was installed, but I still think felt can work if you’re careful and the weather cooperates. Synthetic’s easier to handle, sure, but it can be slippery as ice on a steep pitch... not a fan of that.
Synthetic’s easier to handle, sure, but it can be slippery as ice on a steep pitch... not a fan of that.
That’s my main gripe with synthetic too—on anything over a 6/12 pitch, it feels like you’re working on a skating rink. I’ve seen more than one guy take a slide. As for 30 lb felt, I’ll admit it’s held up for me in stretches, but I’ve also had it wrinkle up in humid weather or after a hard rain. Did you use cap nails or just staples? Sometimes the fastener choice makes all the difference. Weather’s such a wildcard though...
Synthetic’s definitely slick, but I’ve got to push back a bit on the felt side. Seen just as many issues with felt as with synthetic, especially after a storm rolls through.
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As for 30 lb felt, I’ll admit it’s held up for me in stretches, but I’ve also had it wrinkle up in humid weather or after a hard rain.
- That’s the kicker for me. Down here (Gulf Coast), humidity and sudden downpours are the norm. Felt just can’t keep its shape. Once it wrinkles, you’re fighting leaks before you even get the shingles on.
- Cap nails help, but I’ve still watched felt blow off in a good thunderstorm. Staples are even worse—seen whole sections peel up like a bad sticker.
- Synthetic’s slippery, no doubt, but I’ve found the newer textured stuff (like Sharkskin or Titanium) gives a bit more grip. Not perfect, but better than the old blue tarps they used to call underlayment.
- On steep pitches, I just use roof jacks and harnesses. Not ideal, but I’d rather deal with that than have to redo felt after every rain.
- Cost-wise, synthetic’s a little more upfront, but I’ve saved on labor and repairs. Haven’t had to replace a single sheet mid-job since switching.
- One thing nobody talks about: synthetic doesn’t soak up water, so if you get caught in a storm mid-roof, it dries out fast. Felt turns into mush.
Not saying synthetic’s perfect, but for storm-prone areas, I’ll take slippery over soggy any day. Just my two cents.
