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

- Agree with this:

“they hold up better in rain and wind, but they cost more.”

I’ve seen too many folks trust felt and regret it after a surprise storm rolls through - especially in the Midwest, where “chance of rain” means “it’s definitely going to pour.” Synthetics are pricey, yeah, but I’d rather pay up front than deal with soggy felt peeling off my roof. That said, I get the grip thing - synthetic can feel slick, especially if there’s any dew. Still, with how unpredictable the weather’s been lately, I’m not risking it with old-school felt unless the job’s tiny and the forecast is bone-dry.

I totally get the hesitation with synthetic being slippery - almost wiped out myself trying to walk on it before sunrise. But man, the price difference is real. Has anyone found a budget-friendly synthetic that actually holds up? I keep hearing about felt failing in storms, but my neighbor’s roof (with felt) survived last year’s hail just fine. Is it really just luck, or does install quality matter more than the material? I’m in central Illinois, so weather’s all over the place... not sure what’s worth the gamble.

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

I hear you on the synthetic being slick - nearly ate it myself stepping onto a neighbor’s roof after a rain. That said, I’ve gotta push back a bit on the idea that install quality is everything. Sure, a good crew can make almost anything last longer, but there’s only so much you can do with certain materials when the weather goes sideways.

Here’s how I look at it, especially for central Illinois where you get those wild swings - ice one week, tornado sirens the next:

1. **Material matters**. Felt’s been around forever and it’s cheap, but it absorbs water and breaks down faster when it gets wet repeatedly. Synthetics don’t soak up moisture the same way, so if you get a leak or wind-driven rain under your shingles, synthetics won’t turn to mush as quickly.

2. **Install still counts** - but only up to a point. If someone rushes the job or doesn’t overlap layers right, even the best synthetic won’t save you from leaks. But I’ve seen felt literally tear off in big gusts where synthetic just flapped around and stayed put.

3. **Budget options exist**, but some of the super-cheap synthetics are thin as tissue paper and just as useless once they’re torn. I tried one roll from a discount supplier last year - saved $40, but it ripped during install and had to be replaced anyway.

4. **Green alternatives** are out there now too - some recycled-fiber underlayments that aren’t as slippery as plastic-based synthetics and hold up better than felt in storms. They’re not always easy to find at big box stores, but local supply yards sometimes carry them.

I wouldn’t say it’s all luck when a felt roof survives hail or wind; sometimes it’s just that the storm hit at the right angle or missed the worst spots. But over time, especially with all this freeze/thaw stuff we get in Illinois, I’ve watched felt roofs need patching way sooner than synthetic ones.

If cost is tight, maybe look for a mid-grade synthetic or ask around about those recycled options. And if you go with felt anyway, just make sure whoever installs it really knows their stuff - tight overlaps, no shortcuts.

Hope that helps clear things up a bit... roofing always feels like rolling dice no matter what you pick.

That’s really helpful, thanks. I’m in my first house and the roof’s due for new shingles soon - leaning toward synthetic after hearing about felt tearing in storms. Has anyone noticed a difference in attic temps or ventilation between the two? Wondering if that matters much.

Has anyone noticed a difference in attic temps or ventilation between the two? Wondering if that matters much.

I’ve been up in a lot of attics after both felt and synthetic installs, and honestly, I haven’t seen much of a difference in attic temps or ventilation just from underlayment choice. Ventilation’s more about your soffit and ridge vents than what’s under the shingles. Synthetic’s tougher in storms for sure - seen felt rip right off in a bad wind, but never noticed it changing attic heat one way or another.

I’ve always leaned toward synthetic for durability, especially here in the Midwest where storms can get wild. Like you said, I’ve seen felt peel up or even disintegrate after a few wet/dry cycles, while synthetic just hangs tough. But I do wonder if anyone’s noticed issues with synthetic getting slick during install? Some of my crew have complained about footing, especially on steeper pitches.

As for attic temps, I agree - never really noticed a difference tied to underlayment. It’s all about airflow and insulation up there. What I have seen is felt starting to wrinkle or buckle if it gets soaked before shingles go on, which can make the finished roof look a little off. Curious if anyone’s had long-term issues with synthetic breaking down under shingles after 10+ years? Haven’t torn off enough old synthetics yet to say for sure…

I hear you on the synthetic getting slick - my neighbor’s crew had a guy slip last fall, so it’s definitely a thing. Still, I’d rather deal with that than felt turning to mush after a week of rain. Haven’t seen any old synthetics fail yet, but I’m watching too.

- Price was my main reason for sticking with felt last time - synthetic was almost double at my local yard.
- But yeah, after two bad storms, the felt started curling up and I had to patch it.
- Haven’t tried synthetic myself, but I’m wondering if it’s worth the extra up front.
- Anyone notice a difference in how long the synthetic actually lasts before you need to reshingle?
- Midwest weather here - lots of freeze/thaw, if that matters.

But yeah, after two bad storms, the felt started curling up and I had to patch it.

That’s exactly what pushed me toward synthetic the last time we did a roof. The upfront cost stings, no argument there, but I’ve seen way fewer call-backs for leaks or repairs since making the switch - especially after those freeze/thaw cycles you mentioned. Has anyone actually had felt last more than 7-8 years in Midwest winters? I’m curious if it’s just our area, or if others are seeing the same thing.

Interesting question about felt lasting more than 7-8 years in Midwest winters. I’ve only seen it hold up that long if the roof pitch is steep and there’s zero shade or pooling, but even then, curling edges seem pretty common after a few rough seasons. Has anyone tried layering felt with an ice & water shield in trouble spots? Wondering if that combo gets you a bit more mileage, or if it’s just delaying the inevitable.

Has anyone tried layering felt with an ice & water shield in trouble spots? Wondering if that combo gets you a bit more mileage, or if it’s just delaying the inevitable.

I’ve patched a few valleys and low spots with both, hoping to squeeze out another year or two. It did help with leaks after heavy snow, but honestly, the felt still started curling at the edges after a couple of rough winters. Midwest weather just seems brutal on anything that isn’t synthetic. Still, I get wanting to stretch things - sometimes you just need a little more time before a full redo.

I’ve definitely noticed the same thing with felt - it just doesn’t hold up once you get a couple freeze-thaw cycles. I tried doubling up in a few problem spots on an older duplex, but the wind still managed to get under the edges eventually. The synthetic stuff seems to stay put better, but it’s pricier upfront. Has anyone had issues with synthetic getting slick to walk on during install? That’s been my only gripe so far...

Yeah, I’ve had the same issue with synthetic underlayment getting slick - especially if there’s any dew or frost in the morning. What I do now is keep a pair of those cheap rubber-grip gloves handy and try to avoid stepping on the seams. It’s definitely more stable than felt once it’s down, though. I will say, if you’re working on a steeper pitch, it’s worth taking your time and maybe even chalking out your path before you start laying shingles. The price stings, but I haven’t had to go back and patch wind damage like I did with felt.

I get what you’re saying about synthetic being more stable once it’s down, but I’m honestly still on the fence. My house is only a few years old, and the builder went with felt underlayment under asphalt shingles. We’ve had a couple of nasty windstorms here in the Midwest, and I haven’t noticed any issues with the felt shifting or tearing, even though I keep hearing about wind damage. Maybe it’s just luck, or maybe it’s because the roof isn’t super steep.

One thing I do like about felt is it doesn’t get nearly as slippery when it’s damp. I tried helping a neighbor with synthetic underlayment last fall, and I was surprised how slick it got just from morning dew. Even with grippy gloves, I felt like I was skating around up there. I know synthetic is supposed to last longer and be more tear-resistant, but for a DIYer like me, the safety factor with felt is hard to ignore.

I guess it depends a lot on your climate and how steep your roof is. For now, I’m sticking with felt, but I’m definitely watching how the synthetic holds up for others.

- Totally get what you mean about felt being less slippery. I’ve nearly wiped out on synthetic a couple times, especially early in the morning when there’s dew.
- Around here (central Illinois), most of the older roofs still have felt and seem to hold up fine unless there’s a really bad storm.
- Synthetic is lighter and easier to haul up, but yeah, it can be sketchy to walk on. I’ve seen some brands with more grip, but not all of them are great.
- For DIY, I’d probably stick with felt too unless you’re dealing with a super steep pitch or crazy weather.
- One thing - synthetic does seem to last longer if the shingles get delayed, but if you’re shingling right away, felt’s just easier to work with.

I get where folks are coming from about felt being easier to walk on, especially when it’s damp. But I’ve seen a lot of storm damage over the years, and honestly, synthetic has saved a few jobs for me when the weather turned ugly and shingle delivery got delayed. Someone mentioned,

“synthetic does seem to last longer if the shingles get delayed, but if you’re shingling right away, felt’s just easier to work with.”

If you’re in an area where storms pop up out of nowhere or contractors are booked solid, synthetic might be worth the hassle of being a little slicker underfoot. Some brands have a sandpaper-like texture now, which helps a bit. I still keep a pair of those grippy shoe covers handy just in case. Not saying felt’s bad - just that synthetic’s weather resistance has bailed me out more than once.

I’ve had both on my place - felt years ago, synthetic more recently. Up here in the Midwest, storms are unpredictable, and synthetic just holds up better if things get delayed. It’s a little slick, but I’ll take that over replacing soaked felt any day.

I’ve noticed the same thing with synthetic, especially during those stretches where rain keeps popping up in the forecast. It definitely seems to handle moisture better than felt, but I do wonder about long-term UV exposure if the shingles get delayed for weeks. Has anyone had synthetic underlayment exposed for a month or more? Curious if there’s any breakdown or curling over time, since I’ve only had mine uncovered for about two weeks before finishing.

I’ve had synthetic underlayment exposed for just over a month last summer when my contractor got delayed. It held up way better than I expected - no curling or tearing, even with a couple of nasty storms. The color faded a bit, but nothing major. I was worried about UV too, since the packaging said “30 days max,” but honestly, it looked fine. Felt always seemed to wrinkle and get soft if it rained, so I’m sticking with synthetic for now, even if it costs a bit more upfront.