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

I’ve got a low-slope roof in the Midwest, and after a nasty ice dam a few years back, I’ll never skip ice and water shield in the valleys again. The first time, I just used standard felt - big mistake. Water found its way in and I ended up replacing a section of decking. Since switching to a thicker shield, not a single issue, even with heavy snow. I do think some folks go overboard with full coverage, but in those trouble spots, it’s worth every penny.

Ice and water shield in the valleys is like giving your roof a bulletproof vest - especially around here where winter likes to throw curveballs. I’ve seen felt just give up and wave the white flag after one bad freeze-thaw cycle. Full coverage everywhere seems overkill, but those trouble spots? Worth every cent, unless you enjoy surprise indoor waterfalls.

- Ice and water shield in valleys? No-brainer, especially with our freeze-thaw mess.
- Full coverage everywhere... eh, I’ve seen it drive up costs fast, and not always needed unless you’ve got a super low slope or chronic leaks.
- Standard felt just doesn’t cut it in the valleys - seen too many rot-outs after a rough winter.
- Synthetic underlayment’s tougher than felt, but still not a match for ice and water in the real problem spots.
- I’d say: valleys, eaves, and around chimneys - shield it. Rest of the roof? Depends on your budget and how paranoid you are about leaks.

I’m with you on not going full ice and water everywhere - my last quote for that was wild. I did shield in the valleys and around the chimney, then synthetic for the rest. Anyone had issues with synthetic getting slippery or tearing during install? I’ve heard mixed things, but it seemed fine on my 6/12 pitch.

Title: If Underlayments Could Talk: Which One Would Outlast the Others?

I’ve been eyeing synthetic underlayment too, mostly because the price for full-coverage ice and water was just out of reach for my budget. I did a combo last summer - ice and water in the valleys, around the eaves, and synthetic everywhere else (roof is about a 7/12). Didn’t notice any major slipping or tearing either, but I was careful and it was a cool, dry week. I’ve heard stories about synthetic being slick, though, especially if it gets wet during install. Did you do yours in dry weather?

One thing I’m still not sure about is how these synthetics actually hold up after ten years under shingles compared to felt. I read somewhere that some synthetics can get brittle over time, but then again, felt seems to rot if there’s even a hint of moisture. Has anyone done a tear-off on a roof with older synthetic underlayment and seen how it holds up? Does it actually last as long as they claim? I’m not planning on re-roofing for a while, so I’d rather not find out the hard way.

Also curious if anyone’s insurance company cared what underlayment you used? Mine didn’t mention anything, but I’ve heard of some pushing for full ice/water in certain areas. Not sure if that’s just sales talk from contractors or if it actually impacts coverage.

For what it’s worth, the main issue I had was the staples not holding as well in some spots - maybe I should’ve used cap nails everywhere, but that would’ve added up fast. Anyone else run into that? Or am I just being too picky?

I’ve wondered the same thing about how synthetics actually hold up long-term. I helped my uncle tear off a roof last fall - house was built around 2011, so about 12 years on it. They’d used a synthetic underlayment (I think it was Titanium UDL or something similar) under architectural shingles. Honestly, it looked way better than the felt we pulled off his garage from a previous re-roof. The synthetic was a little faded and had some spots where it got brittle, especially near the ridge where the sun probably cooked it more, but it hadn’t disintegrated or stuck to the deck like old felt tends to. The felt on the garage, on the other hand, was basically paper mache in the valleys - just fell apart if you looked at it wrong.

One thing I’ll say is, synthetic is definitely slick if you get any dew or rain on it. I nearly ate it stepping onto a patch that was still drying out in the morning. Not my most graceful moment. I’d rather deal with that than felt turning to mush, though.

On the insurance front, I haven’t heard of anyone getting denied or dinged for using synthetic instead of felt, at least not around here (Midwest). The only time I’ve seen insurance get picky is after big hail storms - they want ice and water shield in certain spots before they’ll sign off on coverage, but usually just in valleys and eaves. Full-coverage ice/water is nice for peace of mind, but yeah, that price tag hurts.

As for fasteners, I’ve had staples pull out too, especially if you catch a knot in the sheathing or if the staple gun’s not set right. Cap nails definitely hold better, but I get what you mean about the cost and time. My boss always says “use cap nails where it matters most” - edges, valleys, anywhere wind might get under. Rest of it, staples if you’re careful. Maybe that’s just old-school thinking, but it’s worked for us so far.

Anyway, you’re not being too picky. If you’re up there doing the work yourself, you want it done right. No shame in sweating the details - beats worrying about leaks down the road.

The synthetic was a little faded and had some spots where it got brittle, especially near the ridge where the sun probably cooked it more, but it hadn’t disintegrated or stuck to the deck like old felt tends to.

That’s what sold me on synthetic too. I pulled up a section of felt from my attic hatch (installed 2008) and it was basically glued to the OSB - total mess. Synthetic seems to age more gracefully, even if it gets a bit crispy in the sun. Still, that slipperiness is no joke... I almost did a full cartoon banana peel slip last summer. I’ll take a little extra caution over scraping felt off plywood any day.

Yeah, that slipperiness is no joke. I nearly slid right off a low slope last fall - synthetic felt feels like ice if there’s even a little dew. But honestly, I’d rather deal with that than the nightmare of scraping old black felt off the decking. The stuff just welds itself on after a few years, especially in humid spots. I’ve noticed synthetic holds up better around vents and edges too, where felt always seemed to crack or curl on me. Still, I kinda miss how felt would soak up a bit of water during install... synthetic just beads it up and runs it right into your boots.

That “ice rink” feeling with synthetic is real - first time I stepped on it, I nearly did the splits. Here’s how I try to keep things sane: 1) Always check the forecast and avoid early morning dew if you can. 2) Use those grippy shoes, not your old sneakers (learned that the hard way). 3) For edges and vents, I’ll tape or double-layer synthetic since felt always curled up there for me too.

I do miss how felt would just kind of hug the deck, especially during a humid install. But man, scraping off old felt is a nightmare... It’s like it fuses into the plywood. Synthetic’s easier when it’s time to redo things, at least in my experience. Still not sure about water running straight into my socks though - there’s gotta be a trick for that, right?

- Totally agree about synthetic being slick - seen a few close calls on job sites, especially with morning dew.
- For water sneaking into socks, I’ve had luck overlapping seams a bit more than the manufacturer says, plus rolling out in the afternoon when things are drier.
- Felt is definitely a pain to scrape up. I’ve seen it take hours, especially on older decks where it’s basically glued down from years of heat.
- One thing I’ll say: synthetic holds up better against wind before shingles go on, but I do miss how felt just settles and stays put in humid weather.
- If you’re worried about leaks at vents or valleys, flashing tape underneath has saved me more than once. Not perfect, but it helps.

I get the appeal of synthetic, especially with how it stands up to wind, but I’m still not sold on the price tag. I used felt on my last roof (asphalt shingles, Midwest winters), and yeah, it was a pain to tear off after 15 years, but it did its job. I do wonder if all the new synthetics really last that much longer in real-world conditions or if it’s just marketing. Also, that slickness is no joke - my neighbor’s roofer nearly took a tumble last fall. For me, felt’s mess is worth the peace of mind, at least for now.

I’m right there with you on the felt. I’ve done two roofs now - both with asphalt shingles, both Midwest winters - and while tearing off the old felt was a sweaty mess, it held up fine for 18 years on my last place. I looked at synthetic this time around, but the price made me pause too. Maybe it’s just me, but I’d rather deal with a little extra cleanup than pay double for something that might not actually outlast the shingles themselves.

That slickness is no joke either. My cousin’s crew had to lay down extra boards just to keep from sliding off when they tried synthetic last year. Not worth the risk in my book, especially if you’re doing any of it yourself.

I get why folks like synthetic - lighter rolls, less tearing in wind - but for my money, felt’s still got a place. Maybe if I lived somewhere with constant rain or crazy winds I’d think different, but here? Felt’s messy but reliable.

Felt’s definitely got a track record, especially in the Midwest where you’re not dealing with constant moisture. I’ve seen plenty of roofs where the felt outlasted the shingles by a few years, which says something. The synthetic stuff is tempting for the weight and wind resistance, but that slick surface is a real hazard - especially if you’re not used to it. Honestly, unless you’re in a spot with wild weather or super steep pitches, sticking with felt makes sense. Cleanup’s a pain, but at least you know what you’re getting.

Had a job last spring where the homeowner insisted on synthetic because his buddy swore by it. Fast forward to a surprise thunderstorm mid-install and half the crew ended up sliding around like it was an ice rink - one guy nearly took out the chimney. I get the appeal, but for basic Midwest roofs, felt’s just less drama. Cleanup’s a pain, but at least you’re not risking a trip to the ER every time it rains.

“half the crew ended up sliding around like it was an ice rink - one guy nearly took out the chimney.”

That’s exactly what I worry about with synthetics - sure, they’re lighter and don’t wrinkle as much, but the slip factor is no joke. I had a crew do my garage last year and they switched to synthetic halfway through because of a supply issue. Even just morning dew made it sketchy for them. For a simple gable roof in the Midwest, felt might be messier, but at least you know where your footing is. Maybe on steeper pitches or fancier roofs the trade-off makes sense, but for most houses around here, I’d rather deal with a little tar paper cleanup than a busted leg.

That “ice rink” feeling is real - synthetics can be downright treacherous, especially when there’s dew or a bit of frost. I get why folks like felt for walkability. Still, I’ve seen synthetics save a ton of headaches in wet climates since they don’t soak up water and wrinkle like felt does. On my last job, we used a textured synthetic with a bit more grip and it made a noticeable difference, but I’d never trust the super-slick stuff on a steep pitch. Guess it depends if you’re prioritizing safety during install or long-term durability... sometimes it’s a toss-up.

- I get the safety concern with slick synthetics, but honestly, I’ve had more issues with felt tearing or shifting in high winds than slipping on synthetic.
- In my area (lots of rain, not much frost), felt just doesn’t hold up - ends up soggy and brittle after a season or two.
- Textured synthetics are a game changer for grip, but even the basic stuff is easier to patch if it gets damaged.
- For me, long-term durability outweighs the install-day walkability... but I can see why folks working on steep roofs might feel differently.
- Maybe it’s just what you get used to, but I’d rather deal with a little slipperiness than have to replace underlayment after every storm.

For me, long-term durability outweighs the install-day walkability... but I can see why folks working on steep roofs might feel differently.

I get the durability argument, but my wallet starts sweating when I see the price tags on some synthetics. I’ve patched felt with duct tape and crossed my fingers through a few storms - sometimes it holds, sometimes not, but at least it’s cheap to replace. Maybe I’m just stubborn, but if I can squeeze another year out of felt for half the cost, I’ll risk a little sogginess. My roof’s not that steep, though, so maybe I’m just lucky (or cheap).

I hear you on the cost - synthetics can sting, especially if you’re used to rolling out felt and calling it a day. I’ve seen plenty of patched-up felt limp through a storm or two, but after a big hail event last spring, the folks with synthetics had way fewer leaks to chase. On a low-slope roof, though, you might get away with felt for longer... just depends how much risk you’re willing to take when the weather turns ugly.

I’ve been weighing this exact trade-off for a while now, especially after managing a couple of buildings with different underlayments. The cost difference is real - synthetics are pricier up front, but I keep coming back to the long-term math. After a few years, the felt roofs seem to need patching or even full replacement sooner, especially after heavy storms. I’ve had tenants call about leaks where the only failure point was the old felt curling up or tearing at the seams.

But then again, on a low-slope roof, like you mentioned, felt can hang in there if you’re not in a high-wind or hail-prone area. I’ve got one flat-roofed property with basic felt that’s held up for almost a decade, but it’s in a pretty mild climate - rarely any hail, and wind isn’t much of an issue. Still, I’m always a little on edge during storm season, wondering if this is the year it finally gives out.

One thing I’m curious about: has anyone actually tracked the maintenance costs over time for both types? I’ve seen some numbers tossed around by contractors, but they’re all over the place. My experience is that synthetics cut down on emergency repairs, but you’re paying more up front and maybe not seeing the savings until year 7 or 8. Does that line up with what others have seen?

Also, how are folks handling warranties? Some manufacturers won’t honor shingle warranties if you use felt instead of their branded synthetic underlayment. That’s been a headache for me when dealing with insurance claims after storms - insurers love to find reasons not to pay out.

I get why people stick with felt for budget reasons, but I’m starting to lean toward synthetics for anything with a steeper pitch or in areas where weather is unpredictable. Still not sure it’s worth it for every roof, though... especially if you’re just trying to get another five years out of an old building before a bigger renovation.