I get the concerns about synthetic, but I’ve had the opposite experience on my last project. Up here in the Midwest, we get a ton of freeze/thaw and felt just didn’t hold up for me—got brittle and tore after a couple winters. The synthetic was definitely slicker when wet, but I found if you use the right shoes and take your time, it’s manageable. Price stings for sure, but not having to redo it every few years saved me more hassle in the long run. That said, tracking down leaks is a pain—felt does seem to “telegraph” issues sooner, you’re right about that.
The synthetic was definitely slicker when wet, but I found if you use the right shoes and take your time, it’s manageable.
That slickness caught me off guard the first time—nearly did a cartoon banana peel move. I started using those grippy roofing shoes and it made a world of difference. I do miss how easy it was to spot a leak with felt though... with synthetic, I feel like I’m playing hide and seek every spring. Still, not having to patch up torn underlayment after every rough winter is a win in my book.
I get what you mean about leaks being harder to spot with synthetic. For me, though, the trade-off is worth it—felt always seemed to tear up around the vents and edges after a couple of freeze-thaw cycles. I actually started using a combo: synthetic on the main roof, but I still put felt around the chimney and valleys where I want to keep an eye on things. Not sure if that’s overkill, but it’s worked so far. Anyone else try mixing materials, or am I just making more work for myself?
I actually started using a combo: synthetic on the main roof, but I still put felt around the chimney and valleys where I want to keep an eye on things. Not sure if that’s overkill, but it’s worked so far.
That doesn’t sound like overkill to me, honestly. I’ve been tempted to do something similar, but mostly because I’m always trying to stretch my dollar and avoid having to redo stuff every few years. My place is an old ranch with a low slope, and the last time I used all felt, it was a mess after two winters—edges curling up, and I swear the stuff just disintegrated around the vent pipes. I switched to synthetic last time, but I’ll admit, it’s a little unnerving not being able to spot leaks as easily. I’m always paranoid I’ll miss something until it’s too late.
Mixing materials seems smart, especially around the chimney and valleys. Those are always the trouble spots for me, too. I had a buddy who did something similar—he used ice and water shield just in the valleys and around the skylights, then synthetic everywhere else. He swears by it, but I always wondered if that’s just making things more complicated (and expensive) than they need to be.
Did you notice any big difference in cost or install time doing it that way? I’m always trying to balance “do it right” with “don’t spend a fortune.” Sometimes I feel like I’m just making more work for myself, but then again, I’d rather patch a little felt than rip up a whole section of synthetic if something goes wrong.
Curious if anyone’s had issues with warranties when mixing underlayments? I’ve heard some shingle manufacturers get picky about that, but maybe that’s just the big brands trying to cover themselves.
Mixing underlayments isn’t as wild as some folks make it sound. I’ve done synthetic for the main field and ice/water shield in valleys and around penetrations, and honestly, it’s held up better than anything else I’ve tried. My roof’s a 5/12 pitch with a couple of dormers, so those valleys are leak magnets if you don’t baby them.
Cost-wise, the synthetic rolls go down faster and cover more area per roll, so labor was actually quicker for me. The ice/water shield is pricier but you’re only using it in the high-risk spots. I probably spent an extra $100-150 on materials overall, but I’d rather pay that than deal with rotten decking later.
Warranties are a gray area. Some shingle brands want you to use their whole system or they get fussy if you mix products. I called GAF when I did mine, and as long as the underlayment met code and was installed right, they didn’t care. But yeah, always check the fine print... some companies love loopholes.
Honestly, patching felt is easier if there’s a problem, but synthetic just doesn’t seem to fail as fast. I’ll take the tradeoff.
