If underlayments could talk: which one would outlast the others?

I get where you’re coming from, but I still lean toward synthetic for the long haul, especially with all the freeze/thaw cycles we get. I’ve seen felt hold up, sure, but it always seems to get brittle or tear up around the fasteners after a few years. Maybe it’s just the way my roof faces the wind, but I’ve had to patch felt more than once. I do agree, though - if the flashing’s a mess or the vents are blocked, it’s game over no matter what you put down. Still, I’d rather start with something that gives me a fighting chance.

I’ve seen felt hold up, sure, but it always seems to get brittle or tear up around the fasteners after a few years. Maybe it’s just the way my roof faces the wind, but I’ve had to patch felt ...

That’s been my experience too - felt just doesn’t handle the temperature swings well. I’ve seen it start curling up or cracking at the seams after a couple of rough winters. The synthetic stuff seems to lay flatter and doesn’t soak up moisture, which probably helps in our climate. That said, I’ve also noticed install quality matters a lot. Even with synthetic, if the fasteners aren’t right or the laps aren’t tight, wind will find a way in. I’d still take synthetic for the durability, but nothing really saves you if the flashing’s not done right.

If underlayments could talk: which one would outlast the others?

Honestly, I’ve torn off more felt that looked like dried lasagna noodles than I care to remember. Synthetic’s definitely tougher in my book, but if you skip the cap nails or overlap like you’re gift-wrapping a football, it’ll still blow right off. Flashing’s the real MVP though - mess that up and you’ll be chasing leaks no matter what you put underneath.

Had a call last winter - old bungalow, original felt underlayment from the ‘80s. Looked like someone left a stack of burnt tortillas up there. But what really got me was the flashing around the chimney... or what was left of it. Water had been sneaking in for years, rotting out the decking. Even with the fanciest synthetic, once that flashing fails, you’re just buying time. I see it all the time - underlayments matter, but flashing’s where most folks get burned.

- Gotta agree with this part:

Even with the fanciest synthetic, once that flashing fails, you’re just buying time.

- I get why folks love synthetics (lighter, easier to handle, supposed to last longer), but honestly? If you’re on a budget like me, it’s hard to justify double or triple the price when most leaks I hear about are from bad flashing or missing shingles - not the underlayment itself.

- My place is a ‘90s ranch, original felt under asphalt. Midwest winters and all. Had to patch a couple spots last year, but the felt was still doing its job where everything else was sealed up right. Not pretty, but not leaking either.

- Flashing is always where things go sideways. Chimneys, valleys, skylights... doesn’t matter what’s underneath if water’s getting in at those spots.

- If I had to pick:
- Felt = cheaper up front, works fine if you keep up with maintenance
- Synthetic = lighter and maybe lasts longer (if nothing else fails first), but costs more
- Ice & water shield = great for trouble spots (eaves/valleys), but not cheap

- For me? I’d rather spend extra making sure the flashing’s done right and maybe add ice & water shield in the worst spots than blow my whole budget on fancy underlayment everywhere.

- Not saying underlayments don’t matter - they do - but if you’re pinching pennies, focus on what actually keeps water out day-to-day. That’s usually metal and caulk, not just what’s rolled out underneath.

- Just my two cents as someone who’d rather fix things once than pay for “upgrades” that don’t solve the real problem.

You nailed it with the flashing focus. I’ve seen too many folks drop cash on “premium” underlayments, but then a lazy flashing job ruins the whole thing. I’m all for greener, longer-lasting materials, but if the metalwork’s sloppy, it’s just landfill in a few years anyway. Your approach - prioritize the spots where leaks actually start - makes way more sense than chasing marketing claims.

That’s exactly what I ran into last year - spent extra on a “lifetime” underlayment, but the real headache was tracking down a leak from a poorly done chimney flashing. Honestly, I’d rather have basic felt with solid flashing than the fanciest underlayment and shortcuts around the vents. It’s wild how much marketing overshadows the basics sometimes...

Honestly, I’d rather have basic felt with solid flashing than the fanciest underlayment and shortcuts around the vents.

I get where you’re coming from - flashing is non-negotiable, and a bad install there will ruin any roof, no matter what’s underneath. But I wouldn’t write off high-end underlayments entirely. In my experience, especially on low-slope roofs or spots that see ice damming, the right synthetic or self-adhered membrane can be a lifesaver. Basic felt just doesn’t hold up to standing water or wind-driven rain the way some of these newer products do.

That said, I’ve seen plenty of “lifetime” underlayments fail early because someone skipped the basics - like not sealing around pipe boots or using cheap caulk at penetrations. It’s not really an either/or situation. You need both: quality materials and proper detailing. Marketing does oversell some of this stuff, but there’s a reason codes are pushing for better underlayments in certain climates. If you’re in a spot with heavy snow or wild temperature swings, it’s worth considering more than just felt - even if it costs more upfront.

I get the whole “don’t skimp on flashing” argument, but I gotta say, I’m not totally sold on the pricier underlayments for every situation. Like, I live in central Illinois - lots of wind, some snow, but nothing like what folks up north deal with. When I had my roof redone five years ago, the contractor tried to upsell me on some fancy synthetic stuff. I ended up sticking with 30# felt because, honestly, my budget was already stretched. I did make sure they didn’t cut corners on the flashing and around the chimney, though.

Funny enough, my neighbor across the street went all-in on the “lifetime” synthetic underlayment. His roof is only three years old and he’s already had leaks around his skylights. Turns out, the crew didn’t bother sealing the flashing right - just like you said:

“I’ve seen plenty of ‘lifetime’ underlayments fail early because someone skipped the basics - like not sealing around pipe boots or using cheap caulk at penetrations.”

Not saying the new stuff doesn’t have its place. If I lived somewhere with crazy ice dams or a super low slope, maybe I’d think differently. But for a standard roof and a tight wallet, I’d rather spend extra making sure the install is done right than on a product that’s only as good as the guy nailing it down. Maybe that’s just me being stubborn, but I’ve seen too many “upgrades” go sideways because someone got lazy with the basics.

If I ever have to do it again, I might look at the newer membranes just for the peace of mind. But only if I trust the crew to actually do it right. Otherwise, I’ll stick with what’s worked and put the savings toward something I can actually see - like gutters that don’t leak every spring.

- Totally get where you’re coming from.
- I’ve seen more issues from sloppy installs than from the underlayment itself, honestly.
- You nailed it - flashing and details matter way more than the brand of felt or synthetic.
- My last roof was 30# felt too, and it’s still solid after a decade.
- Sometimes the “latest and greatest” just means more expensive headaches if the crew cuts corners.
- Gutters that actually work? Now that’s money well spent...

Sometimes the “latest and greatest” just means more expensive headaches if the crew cuts corners.

That’s been my experience too. I’ve seen fancy synthetics wrinkle up or tear because someone rushed the job. Meanwhile, old-school felt just keeps hanging in there if it’s put down right. Details really do make or break it.

Meanwhile, old-school felt just keeps hanging in there if it’s put down right.

I’ve patched up more than a few roofs after storms where the only thing holding back leaks was that old felt. One job, the shingles were half gone but the felt underneath was still doing its job - probably because the installer took their time. I get why folks like synthetics, but if you don’t lay them flat or fasten them right, they can bunch up or even rip in high winds. Sometimes “new and improved” just means more ways for things to go sideways if you’re not careful.

Funny thing - I’ve seen both felt and synthetics hold up, but it really does come down to how careful you are with the install. I’ll admit, I’m partial to the newer recycled-fiber underlayments, especially when you’re trying to keep things eco-friendly and still want decent water resistance. But yeah, if you rush it or skip a few fasteners, even the fanciest stuff can flap around like a loose tarp in a storm. Sometimes the “old ways” stick around for a reason...

I’ve had a similar experience - recycled-fiber underlayments are my go-to these days, mostly because I feel better about the environmental impact. That said, I learned the hard way that if you don’t overlap and fasten properly, even the “green” stuff can let you down. Had a section peel up during a windy week last fall... lesson learned. The old felt rolls are forgiving, but man, they’re heavy and messy to haul around.

I hear you on the weight of felt - lugging those rolls up a ladder is no joke. I’ve had better luck with synthetic underlayments lately, especially in our wet springs, but I’m still not sure how they’ll hold up long-term. Anyone tried both on a low-slope roof? I wonder if one handles pooling water better than the other...

I’ve put both to the test on a 2/12 pitch, and honestly, synthetics have been less stressful during install - lighter, easier to handle. But when it comes to pooling, traditional felt still seems to tolerate standing water a bit better before the shingles go on. Synthetics can get slick and don’t always seal around fasteners as well, at least in my experience. If you’re in a spot with a lot of freeze-thaw or heavy rain, I’d still lean toward something with a solid water barrier rating, maybe even consider a self-adhered membrane for those trouble spots.

Felt’s definitely old reliable when it comes to standing water - seen it outlast a few surprise storms before the shingles went on. But man, those synthetics are a back-saver. Ever had one of those windy days where the felt just wants to become a kite? Curious if anyone’s had luck with peel-and-stick on low slopes - does it hold up long-term, or just a pain to repair later?

Peel-and-stick’s actually held up better than I expected on low slopes, especially in spots prone to ice damming. It’s a pain if you ever have to tear into it for repairs, though - sticks like crazy and can pull up decking if you’re not careful. Still, for long-term water resistance, it’s hard to beat in tricky areas. Just don’t skimp on prep or you’ll regret it later.

Peel-and-stick is wild stuff. I used it on a porch roof with barely any pitch and, honestly, it’s been bombproof against leaks - even after a couple of gnarly ice storms. But yeah, if you ever have to patch something, it’s like wrestling a sticky octopus. I learned the hard way - pulled up a chunk of plywood by accident. Prep is everything, though. If there’s even a hint of dust or moisture, you’ll be cursing later when bubbles show up.

- Peel-and-stick is a beast for low-slope spots, no doubt.
- But man, once it’s down, it’s down... I’ve seen more than one repair job turn into a full deck replacement because of that tenacious grip.
- I’ll take the hassle over leaks, but for bigger roofs, I still go synthetic - way easier if you need to patch later.
- Prepping the surface is everything. One time, a roofer skipped cleaning and the whole sheet bubbled up after a summer rain. Rookie move.