That’s wild, I’ve seen the same thing—felt just doesn’t stand a chance in that kind of heat. I inspected a place last August where the felt had basically fused to the OSB, and it took the crew hours to get it off. The synthetic right next to it looked brand new, like you said. I do agree about the slipperiness though... nearly lost my footing more than once. Haven’t tried those premium felts yet either, but honestly, after seeing what regular felt does in a heatwave, I’m skeptical they’d hold up much better. Still, for quick patches or spots that’ll be covered fast, felt’s hard to beat for convenience.
I’ve had the same experience with felt turning into a sticky mess after just a couple days of summer sun. The last time I did a shed roof, the felt was basically glued down by the time I got back to it. But I do like how easy it is to roll out and tack in place for small jobs. Has anyone noticed if synthetic underlayment makes much noise in the wind before the shingles go on? That’s one thing I’ve wondered about, especially for bigger projects where it might sit exposed for a week or two.
I’ve run into that same sticky felt issue, especially during the hotter months. It’s wild how quickly it can basically melt onto the decking if you get a stretch of sun. I get why folks still use it for quick jobs—super easy to handle and cheap—but for anything that’s going to be exposed for more than a day or two, I’ve started leaning toward synthetics.
On the noise front, yeah, synthetic underlayment can definitely flap around if it’s windy and you haven’t got shingles on yet. I had a job last summer where we had to leave the synthetic exposed for almost two weeks (thanks to a delivery delay), and there were a couple of nights where it sounded like someone was shaking a tarp on the roof. Not enough to keep anyone up, but you’d notice it if you’re nearby. The trick is getting enough fasteners in—most of the newer synthetics have those printed nail lines, and if you follow them closely, it helps keep things tight. Some brands are stiffer than others too, so the noise varies.
One thing I do like about synthetics is they don’t turn into that gummy mess, even after baking in the sun for days. Plus, they’re lighter and way less likely to tear if you get a gust of wind while you’re working. That said, I’ve seen some folks complain about them being slippery when wet, so that’s something to watch out for if you’re up there after a rain.
If you’re thinking long-term durability, synthetics seem to hold up better—especially if there’s any chance your project might get delayed or you’re dealing with unpredictable weather. Felt still has its place for quick fixes or small sheds, but for bigger roofs or anything that might sit exposed, I’d go synthetic every time. Just be ready for a bit of flapping if the wind picks up before the shingles go down...
I get the appeal of synthetics, but I’ve actually had felt last just as long under shingles on a couple of my older roofs—one’s pushing 18 years now and still dry underneath. Maybe it’s the milder climate here, but I haven’t seen it break down unless it’s left exposed too long. Synthetics are lighter, sure, but I find them a pain to walk on if there’s any dew or frost. For me, felt’s still got a place for more than just quick fixes.
I hear you on the felt—I've seen it hold up surprisingly well, especially when it's covered quickly and not exposed to heavy UV. In milder climates, felt can absolutely go the distance under shingles. One thing I've noticed, though, is after major storms or wind-driven rain, synthetics tend to resist water intrusion a bit better if the shingles get compromised. But yeah, walking on synthetic when it's slick is no joke... I've nearly ended up on my back more than once. For certain jobs, old-school felt still makes sense.
