finally found an underlayment that lasts - what's your experience?

I hear you on the felt tearing - seen that happen more than once after a windy night, and it’s a pain. I’m still a little skeptical about all the plastic in synthetics, though. Some of those brands claim to be “eco-friendly,” but I haven’t found one that really breaks down or recycles well. I do like the sanded ones for grip, but I wish there was a truly green option that didn’t turn into a slip-n-slide or a landfill problem. Maybe one day...

I get where you’re coming from on the plastic thing. I’ve been wrestling with that myself - my wallet loves the idea of a synthetic underlayment that actually survives more than two winters, but my conscience isn’t thrilled about adding more plastic to the world. I tried one of those “eco” brands last year (can’t remember the name, green label, lots of promises), and honestly, it still felt like glorified tarp. Didn’t tear as fast as felt, but it’s not exactly composting in my yard either.

The sanded ones are nice for grip, but man, when it rains hard, they get slicker than I expected. Nearly took a tumble up there trying to patch a vent. I keep hoping someone will invent something that’s tough, affordable, and doesn’t stick around for 500 years after you’re done with it. Until then, I’m just picking whatever keeps the leaks out and doesn’t break the bank... not perfect, but at least my living room stays dry.

I get the plastic guilt, but honestly, I’m not convinced the “eco” options are all that much better - at least not yet. I tried a recycled-fiber underlayment on my shed last fall, and it started curling at the edges after the first big freeze. Maybe it’s just our Midwest winters, but I ended up patching more than I’d like. I’d rather use something that lasts longer, even if it’s synthetic, than have to replace it every couple years. It’s a tradeoff, but constant repairs seem just as wasteful in the long run.

- Gotta say, I’ve had the opposite experience with the recycled stuff. Used a recycled-fiber underlayment on my garage roof (also Midwest), and it held up fine through two winters so far.
- Maybe it’s a brand thing? Or install method?
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“I’d rather use something that lasts longer, even if it’s synthetic, than have to replace it every couple years.”

- Seen a lot of recycled underlayments go both ways, honestly. Some hold up, some don’t. Always wonder if it’s more about the installer or just luck with batches.
- Midwest winters can be brutal - ice dams, freeze/thaw cycles, all that. I’ve seen synthetic rip up in crazy wind, but I’ve also seen felt disintegrate after a couple years.
- Brand does matter, but prep and install are huge. Did you guys use cap nails or staples? I’ve noticed staples tear through way easier when things get gusty.
- Noticed any issues with moisture getting trapped under the recycled stuff? Had one job where it didn’t breathe as well as advertised, and we ended up with mold.
- Anyone try those hybrid underlayments - part recycled, part synthetic? Curious if they’re actually splitting the difference or just marketing hype…

Had a client last year dead set on using recycled underlayment - trying to be eco-friendly and all that. Install went smooth, but about six months in, we had some weird condensation issues right where the north side got zero sun. Mold city. Maybe it was the batch, maybe just that spot, who knows. Anyone else notice the “breathable” claims don’t always pan out? Still better than felt in some ways, but I’m low-key skeptical about those hybrid options... are they just splitting the problems too?

I’ve wondered the same thing about those “breathable” claims. We tried a hybrid underlayment on our garage roof - supposed to be the best of both worlds, but honestly, it still had some moisture issues in shaded spots. Not as bad as felt, but not perfect either. Anyone actually seen a hybrid hold up well over a few years, especially in damp climates? I’m in the Pacific Northwest, so shade and moisture are just part of life here.

Anyone actually seen a hybrid hold up well over a few years, especially in damp climates? I’m in the Pacific Northwest, so shade and moisture are just part of life here.

I’ve seen similar issues - hybrids seem promising on paper, but in spots that never dry out, moisture still sneaks in. Did you notice any difference in how fast the underlayment dried after a storm? Sometimes I wonder if “breathable” just means it lets vapor through both ways... which isn’t always good. Have you checked for mold or rot under those shaded areas yet? That’s usually where problems show up first.

Sometimes I wonder if “breathable” just means it lets vapor through both ways... which isn’t always good.

That’s a fair point. “Breathable” can be a double-edged sword, especially where you’ve always got shade and dampness. I’ve seen hybrids do okay for a couple years, but the real test is those spots that never see the sun. If you haven’t found any mold or rot yet, you’re ahead of the game - most issues start small and hide under the surface. Keep an eye out, but it sounds like you’re on the right track.

“Breathable can be a double-edged sword, especially where you’ve always got shade and dampness.”

That’s spot on. I’ve replaced underlayment in valleys where the sun never hits, and even the “breathable” stuff can trap enough moisture to cause headaches. Once had a north-facing dormer that looked fine for years - until a big storm hit and water found its way in through some pinholes. Sometimes I wonder if we’re trading one problem for another with these new materials, but at least they’re lighter to haul up a ladder.

That’s been my experience too - sometimes the “breathable” stuff just isn’t enough if you’ve got a spot that never dries out. I had a patch behind my chimney where the underlayment basically turned into mush after a few years, even though it was supposed to let moisture escape. I do like how much easier the new rolls are to handle, but I’m still not convinced they’re always better than old-school felt in tricky spots. Guess it’s always a bit of a gamble, depending on your roof and weather.

I get where you’re coming from, but I’ve actually had better luck with the newer synthetics in those tough spots - especially if you double up or use a peel-and-stick membrane around chimneys and valleys. The trick is making sure the flashing detail is solid and overlaps are tight. Felt’s got its place, but I’ve seen it break down faster than some of the new stuff, especially after a few freeze-thaw cycles. Maybe it’s just our crazy Midwest weather, but I’d take the lighter rolls any day for steep pitches.

Interesting, I’ve had similar issues with felt in the Midwest - seems like it gets brittle after a couple of winters. I switched to synthetic last time just because it was lighter and way easier to handle solo, especially on a steep roof. Have you noticed any difference in noise during storms with synthetics vs. felt? My attic seemed a bit quieter, but maybe that’s just me.

That’s interesting about the noise difference. I’ve always wondered if the underlayment actually makes much of a difference with sound, or if it’s more about the insulation and what’s going on in the attic itself. When I switched from felt to synthetic (I’m in northern Illinois), I didn’t notice a huge change in noise, but my attic is pretty packed with old boxes and insulation, so maybe that muffles things anyway. Did you notice any difference in temperature up there, or just the sound?

I totally get what you mean about handling the synthetic rolls solo - felt was such a pain, especially when it got windy. The lighter weight made a big difference for me too. I do wonder if the synthetic stuff holds up as well long-term, though. Have you had any issues with it tearing or breaking down after a few years? I’m only on year three, so I’m still kind of waiting to see how it does through more Midwest winters.

I’ve wondered about the noise thing too, honestly. When I first put down synthetic underlayment (I’m in central Iowa, so not far from you), I was half-expecting it to make a bigger difference with rain and wind sounds. But like you, my attic’s basically a storage unit at this point - boxes everywhere and a ton of blown-in insulation - so maybe that’s what’s really soaking up the sound. I didn’t notice any real change in temperature either, but I guess I wasn’t expecting much there since the insulation does most of the heavy lifting.

Handling those felt rolls solo was a nightmare... I remember chasing one halfway down the driveway during a gust. The synthetic stuff is so much easier to manage, but I do get what you mean about long-term durability. Mine’s only been on for about four years, so not a huge difference from yours. So far, it’s holding up fine - no signs of tearing or weird wear, and I’ve checked after a couple of nasty storms. I was nervous at first because it just feels so much thinner than the old felt, but it’s tougher than it looks.

One thing I did notice is that the synthetic doesn’t seem to hold moisture the way felt did. I had a minor leak after an ice dam last winter, and the synthetic dried out fast, whereas the felt used to stay damp forever and get kind of gross. Not sure if that matters long-term, but it made cleanup less of a headache.

I’m still waiting to see how it does after a decade or so - Midwest winters are no joke, and I’ve heard mixed things from neighbors. But for now, I’m glad I switched. It’s nice not having to wrestle with those heavy, soggy felt rolls anymore.

You nailed it about the synthetic drying out faster. I’ve seen the same thing - felt just soaks up water and stays damp, which can lead to rot if you’re not careful. Synthetic’s a lot lighter to haul up a ladder too, which my back appreciates. I do think some of the older guys are right to be skeptical about long-term durability, but so far I haven’t seen any real issues, even after some brutal Midwest storms. The only thing I’d watch is making sure seams are tight - wind-driven rain will find any weak spot. Otherwise, I’d take synthetic over felt any day.

I get where you’re coming from about the seams - had a nasty surprise last spring when a gusty thunderstorm found its way under a loose edge of synthetic I’d put down myself. Lesson learned, I double up on fasteners now, especially near the eaves. I’m still a bit on the fence about longevity, though. My neighbor’s roof is only 7 years old with synthetic, and it’s holding up, but I’ve seen felt last decades if it stayed dry. Maybe it’s just luck or local weather... anyone else notice synthetics getting brittle after a few years in the sun?

anyone else notice synthetics getting brittle after a few years in the sun?

Seen that a few times, especially on south-facing slopes where the sun just bakes everything. Some brands seem to hold up better than others, but I wouldn’t say they’re all immune. Doubling up on fasteners is smart - wind loves to find weak spots. I’ve had felt last ages too, but only if it stayed bone dry, which isn’t always realistic around here.

I’ve actually had the opposite experience with felt - mine started curling and tearing after just a couple of wet seasons. Maybe it’s the humidity here, but I couldn’t keep it dry no matter what. The synthetics I tried held up better, though I did notice some brittleness after about five years, like you mentioned. I wonder if ventilation plays a bigger role than we think... I started leaving a bit more gap at the ridge and it seemed to help. Not perfect, but less cracking so far.

Humidity’s a real killer for felt, especially if you’re anywhere near the coast or get those long, damp spells. I’ve seen more roofs rot out from trapped moisture than actual storm damage some years. Ventilation’s huge - honestly, most folks underestimate it. Leaving that ridge gap is smart, but I’d also check your soffit vents and make sure nothing’s blocked up with insulation or debris. Synthetics do get brittle, but at least they don’t turn to mush like felt in wet climates. If you’re still seeing cracking, maybe try a hybrid underlayment? Some of the newer ones balance flexibility and moisture resistance better, though they’re pricier.