Which holds up better over time: felt or synthetic underlayment?

- Seen the same thing with synthetics getting slick - especially early mornings with dew.
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“Curious if anyone’s had trouble with synthetic tearing around fasteners over time?”

I get why folks lean toward synthetics, but honestly, I’m still not convinced they’re always better long-term. My place is in the Midwest, and after a couple of rough winters, the synthetic underlayment started curling up at the edges - especially where the wind hits hardest. Felt might not be perfect in heavy rain, but at least it didn’t get as brittle in the cold for me. Maybe it’s just the brand or installer, but I’m not totally sold on synthetic being the clear winner everywhere.

- Seen the same curling with synthetic on some of our north-facing properties - wind just gets under there after a few freeze-thaw cycles.
- In my experience, felt does stay more flexible in subzero temps, but it can get soggy if the install drags out.
- Installer technique seems to matter a lot. If they don’t fasten the edges well, even the pricier synthetics can lift or wrinkle.
- We’ve had better luck with heavier-weight synthetics, but they’re not all created equal... some cheaper rolls are basically plastic tarps.
- Midwest winters are brutal on anything exposed. I wouldn’t call synthetics a slam dunk either, at least not for every roof or budget.

Installer technique seems to matter a lot. If they don’t fasten the edges well, even the pricier synthetics can lift or wrinkle.

You nailed it - installer skill is half the battle. I’ve seen “premium” synthetics flap around like a car dealership balloon man after a lazy staple job. Midwest wind doesn’t care what you paid for the roll. Hang in there... sometimes it’s just about picking your battles (and your installer).

I’ve managed both types on different properties, and honestly, I’ve seen felt outlast synthetic when the install was meticulous, especially on lower slopes. But with a good installer, synthetics really do hold up to foot traffic and moisture better over time. Curious if anyone’s had issues with synthetics getting brittle after a few years? That’s been my only reservation.

Curious if anyone’s had issues with synthetics getting brittle after a few years? That’s been my only reservation.

I’ve seen that too, especially on properties where the attic gets super hot - synthetic can get kind of crispy over time. Here’s what I usually look for: 1) check the manufacturer’s temp ratings, 2) see how much direct sun exposure it’ll get before shingles go on, and 3) ask around about local installs. Has anyone noticed if certain brands hold up better in high heat? I’m still not convinced synthetics are always the answer, especially for older buildings with poor ventilation.

I kind of get what you’re saying about synthetics getting brittle. When we bought our place (built in the late 70s), the inspector pointed out that the old felt underlayment was still holding up okay under the shingles - just a few spots where it had worn thin. We’re in central Texas, so summers are brutal. I went with synthetic for a patch job last year because everyone said it was “the new standard,” but now I’m second-guessing it after reading stuff like:

synthetic can get kind of crispy over time

I crawled up there last month and noticed the exposed edge already felt stiffer than I expected, and it’s only been a year. Maybe it’s just the brand, but I’m starting to think felt might actually be better for older houses like ours, especially since our attic ventilation isn’t great. Not sure if anyone else has seen this, but I’m definitely watching for any signs of cracking or curling at the seams. Sometimes “newer” doesn’t mean better, I guess...

I crawled up there last month and noticed the exposed edge already felt stiffer than I expected, and it’s only been a year.

Yeah, I’ve noticed that too with the synthetic stuff. We did a small repair on our shed roof last spring using synthetic because it was lighter and easier to handle, but after one Texas summer, it’s already looking kind of warped at the edges. The old felt on our main roof is still hanging in there, even though it’s probably 15+ years old. Maybe felt just handles the heat better, especially if your attic isn’t vented well. I’d keep an eye on those seams, for sure. Sometimes “new standard” just means “cheaper to ship,” not necessarily better for every house.

Here’s what I’ve seen over the years, especially after big storms: synthetic underlayment is lighter and easier to roll out, but it just doesn’t seem to take heat and UV like old-school felt. You get a few months of direct sun - especially somewhere hot like Texas - and those edges start curling or stiffening up. I’ve even seen some synthetics get brittle and crack if they’re left exposed too long before the shingles go on.

Felt’s heavier, yeah, but it seems to “settle in” better and doesn’t mind a little moisture or heat. If there’s a leak or a shingle blows off, felt usually holds up long enough for you to fix it before water gets inside. With synthetic, I’ve seen water sneak under the seams if they start to lift.

If you’re in a spot with wild temperature swings or lots of sun, I’d lean toward felt unless you need something super lightweight for a tricky install. Either way, check those seams every season - especially after storms. A little maintenance now beats a full tear-off later... trust me.

You nailed it - felt just seems to hang in there when the weather gets wild. I’ve had synthetic peel up on me after a couple months of Texas sun, but the old felt just shrugs it off. Maintenance is a pain, but you’re right... beats a waterfall in the living room.

I’ve had synthetic peel up on me after a couple months of Texas sun, but the old felt just shrugs it off.

That’s been my experience too. I put synthetic underlayment on my shed roof a few years back, thinking it’d be a set-it-and-forget-it deal. By the second summer, it was curling at the edges and letting dust in. Meanwhile, my main house still has felt from the early 2000s - sure, it needs patching now and then, but it’s weathered hail and some nasty windstorms without giving up. Maintenance is annoying, but at least I know what to expect with felt. The synthetic stuff just didn’t handle our heat as well as advertised. Maybe up north it’d be different?

I’ve got to say, I’m a little surprised by how quickly some of these synthetics break down in the heat. I manage a handful of rental properties here in central Texas, and when we reroofed a duplex four years ago, the roofer talked up synthetic underlayment like it was the future - lighter, tougher, “guaranteed” to last longer than felt. Fast forward to last summer: we had a string of 100+ degree days, and I started getting calls about leaks. Went up to check and sure enough, the synthetic was curling at the seams and even tearing in spots where it had baked under the shingles. Not what I expected after all that sales talk.

Meanwhile, there’s an old house down the street with felt underlayment from the late ‘90s still holding up (more or less). It’s not perfect - there are spots that need patching every few years, especially after hail - but at least it doesn’t just peel off or get brittle in the sun. You kind of know what you’re getting with felt. It’s not fancy, but it’s predictable.

I do wonder if this is just a southern thing. Maybe those synthetics are better suited for places where you don’t get months of brutal sun? Or maybe there’s a difference in brands - I’ve heard some folks swear by certain synthetics, but my experience hasn’t matched up. Plus, with felt, even if you have to patch it now and then, it’s cheap and easy to work with.

Honestly, if I’m reroofing anything that’s going to sit in direct Texas sun for years on end, I’m leaning back toward good old felt. At least until someone comes out with a synthetic that can actually handle these summers without falling apart...

“with felt, even if you have to patch it now and then, it’s cheap and easy to work with.”

Right? I’ve patched more felt than I care to admit, but at least it doesn’t just turn into potato chips after a couple summers. Tried synthetic on my garage roof - figured I was being all modern - and it basically melted where the sun hits hardest. Maybe I got a dud brand, but I’m not eager to try again. Texas roofs are a different beast...

Man, I feel you on the Texas sun. I thought synthetic was supposed to be the “set it and forget it” option, but mine started curling up at the edges after just a couple years. Maybe it’s just not made for this kind of heat? Felt isn’t perfect, but at least when it gets beat up, you can slap a patch on and call it a day. I’m starting to think “old school” sometimes wins out down here.

I get where you’re coming from, but I’m not totally convinced felt is the answer either, especially with these crazy storms we get. I’ve seen felt tear up and blow off way easier than synthetic, and once water gets under there, it’s a mess. The curling edges on synthetic are annoying, yeah, but I wonder if it’s a brand or install thing? Some of the newer synthetics are supposed to be more UV-resistant. I’d rather deal with a little curling than have the whole underlayment rip off in a windstorm...

You’re not wrong about felt being vulnerable in high winds. I’ve seen plenty of cases where traditional 15# or even 30# felt just couldn’t hold up once the shingles started to lift, especially on steeper slopes or in open areas where the wind really gets under there. Once water finds its way beneath, it’s a headache - rot, mold, you name it.

The curling on synthetics is a pain, but in my experience, it’s often tied to how it’s installed and sometimes the specific product. Some of the budget synthetics don’t lay flat, especially if they’re left exposed too long before shingles go on. The newer UV-resistant synthetics are definitely an improvement, though. I’ve inspected roofs where the underlayment was exposed for weeks and still looked fine.

If I had to pick, I’d lean toward a good-quality synthetic for storm-prone areas, even with the occasional curling. It’s not perfect, but it tends to stay put better than felt when the weather gets wild. Just make sure whoever’s installing it knows what they’re doing - fastener spacing and overlap make a big difference.

Had a similar debate with my contractor a few years back when we re-roofed after a nasty windstorm. I was leaning toward felt just out of habit - my old man always used it - but the last storm peeled half of it up like a sardine can. Water got in, and next thing I knew, I was dealing with stained ceilings and a musty smell that wouldn’t quit.

We went with synthetic the second time around. Not gonna lie, there was some curling at the edges where the crew rushed things, but overall it held up way better when another round of storms hit. I’m in Oklahoma, so wind is just part of life here. The synthetic didn’t tear or let water through, even after sitting exposed for almost two weeks while we waited on shingles.

I do think you get what you pay for, though. My neighbor tried to save a few bucks with bargain-brand synthetic and ended up with more problems than he started with - stuff shriveled up in the sun and tore at the fasteners. If you’re in a windy spot, I’d say spend a little extra for the good stuff and double-check how it’s installed. It’s not perfect, but it’s been less hassle for me than felt ever was.

the last storm peeled half of it up like a sardine can. Water got in, and next thing I knew, I was dealing with stained ceilings and a musty smell that wouldn’t quit.

That’s rough. Wind can be brutal on felt, especially if it’s not nailed down just right or gets left exposed too long. I’ve seen more than a few jobs where the old-school felt just couldn’t keep up with Oklahoma gusts - one time, we had to chase it halfway down the block.

You nailed it about synthetic holding up better, though. The stuff’s lighter, but somehow tougher against tearing and UV. I’ve noticed the same thing with bargain brands, though - sometimes they’re so thin you can see daylight through them. Not worth the headache.

I do think felt still has its place, especially for quick jobs or if you’re shingling right away. But for anything that might sit exposed, synthetic’s been way less drama in my experience. Just gotta watch those edges and make sure the crew isn’t rushing - curling can sneak up on you fast.

Props for sticking it out after that first mess. Roofing’s never boring, that’s for sure...

I’ve seen synthetic take a beating and still hang on, but I’ve also had a roll of it tear right down the ridge when the wind picked up - guess it depends on the brand and install. Has anyone noticed if certain synthetics handle hail better than others?

I’ve seen the same thing - synthetic can be tough, but it’s not all created equal. Some brands really do seem to handle hail better, especially the heavier stuff with more reinforcement. I’ve noticed the cheaper rolls tend to get shredded or even punctured by bigger hail, while the pricier ones just get a few dents and keep going.

Install makes a difference too. If it’s stretched too tight or not fastened right, wind or hail will find a way in. I had one job where we used a mid-range synthetic and after a hailstorm, there were little craters everywhere but no leaks. On another roof with basic felt, it just tore right through.

Honestly, I think climate matters too - down south where hail is more common, folks seem to go for the thicker synthetics. Up north, I still see a lot of felt because it’s cheap and easy to work with, but it doesn’t hold up as well long-term if you get a bad storm.