seeing synthetic hold up that well after 15 years is making me question if it’s worth the extra cost.
I hear you. I used to swear by felt, but after seeing how synthetic handled a couple of nasty hailstorms here in Texas, I’m starting to lean that way too. The upfront cost stings, but not having to patch leaks every few years is a big plus. Still, I’ve seen some older felts outlast the shingles themselves, so it’s not always cut and dry. Depends a lot on your weather and how picky you are about maintenance.
Depends a lot on your weather and how picky you are about maintenance.
That’s a key point. In my area (Pacific Northwest), the constant moisture really tests underlayment. I’ve seen synthetic resist mold and rot way better than felt, but it does get slick if you’re up there working. Curious if anyone’s noticed a difference in energy efficiency between the two? I’ve heard some synthetics reflect heat better, but haven’t seen hard data.
I’ve actually wondered about the energy efficiency thing too. I swapped out old felt for synthetic on my shed roof a couple years back—nothing fancy, just asphalt shingles over the top. Didn’t notice any real difference in the temp inside, but then again, it’s not insulated or anything. The synthetic I used was supposed to have a reflective layer, but honestly, in the PNW, it’s more about keeping the rain out than reflecting heat.
One thing I did notice: the synthetic held up way better after a couple of those classic sideways-rain storms. The felt on my main house roof (installed maybe 12 years ago) started curling and breaking down where water pooled near the eaves. No mold yet, but it’s looking rough. The synthetic on the shed still looks brand new, even after a winter where I forgot to clear off the moss.
I’ve heard some folks say synthetics can make a difference in hotter climates, but up here, I’d say durability and moisture resistance are the bigger wins. Energy savings? Maybe not so much unless you’re in a spot that really bakes in summer.
The felt on my main house roof (installed maybe 12 years ago) started curling and breaking down where water pooled near the eaves. No mold yet, but it’s looking rough. The synthetic on the shed still looks brand new, even after a winter where I forgot to clear off the moss.
- Seen this exact thing on a lot of inspections around here (I’m in western WA). Felt just doesn’t seem to hold up once you get a few years of real rain and those freeze/thaw cycles.
- Had one client with a 15-year-old comp roof—original felt underneath was basically paper mush at the eaves. Meanwhile, their neighbor’s newer roof with synthetic was bone dry underneath, even after some gnarly wind-driven rain last fall.
- Energy efficiency is kind of a non-starter up here unless you’re packing in insulation or have a metal roof that really bakes. Most folks don’t notice much temp difference just from underlayment.
- Durability-wise, synthetic wins out most times. It doesn’t wrinkle or tear as easy when installers walk on it, either. That said, I’ve seen cheap synthetics get brittle after a few years if they’re exposed to sun for too long before shingles go on.
- Only downside I’ve noticed: some synthetics can be pretty slick when wet—had a roofer take a spill last year because of that.
Honestly, in our climate it’s all about moisture resistance and how well the underlayment handles pooling at the eaves/gutters. If you’re not dealing with crazy heat, I’d lean synthetic every time just for peace of mind during those sideways-rain months... which is like half the year here anyway.
I’ve pulled up a lot of old felt that was basically falling apart at the eaves—especially after a few years of pooling water. Synthetic definitely holds up better in wet climates, but you’re right about it being slick when wet. I always warn crews about that. If you go synthetic, just make sure shingles go on soon after, since UV can break down the cheaper stuff pretty quick.