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

I totally get the guilt about all the plastic waste - synthetic does feel a bit like cheating the environment. But after dealing with a couple of insurance claims from leaks (thanks, Midwest storms), I’ve started leaning toward synthetic for rental properties. It just holds up better if the roofers get delayed or we get surprise rain. That said, it’s not perfect - slippery as heck to walk on, and yeah, it’s more landfill fodder. I wish someone would invent a biodegradable version that actually works...

Slippery is right - I nearly did the splits last summer trying to cross a roof with synthetic down. Not my proudest moment, but at least nobody got it on video, right? I hear you on the guilt, though. It’s weird knowing this stuff will outlive me (and probably my grandkids), but man, after seeing what Midwest rain does to old felt, I get why people go synthetic for rentals.

One thing I noticed - felt tears super easy if you’re dragging bundles or tools across it, especially when it’s hot and sticky. Synthetic seems to bounce back unless you really gouge it. But then again, every time I’m up there and it rains, I feel like I’m ice skating... not exactly OSHA-approved.

Has anyone actually tried those “eco” underlayments? I saw one at a supply house that claimed to be biodegradable, but the rep just kind of shrugged when I asked if it actually held up in storms. Curious if anyone’s risked it or if it’s just marketing fluff.

Has anyone actually tried those “eco” underlayments? I saw one at a supply house that claimed to be biodegradable, but the rep just kind of shrugged when I asked if it actually held up in storms.

I’ve tested a couple of those “eco” options on smaller sheds, but honestly, durability’s still a big question mark. They break down faster than synthetics, especially if exposed before shingles go on. Not sure I’d risk them on a full house yet, especially in storm-prone areas. Synthetic’s still the safer bet for now, even if it’s a little guilt-inducing.

They break down faster than synthetics, especially if exposed before shingles go on.

That’s been my experience too. Tried one of those “eco” felts on a detached garage last year, just as a test run. Looked good out of the wrapper, but after a week of rain and wind (didn’t get shingles on as fast as planned), it started curling at the edges and got soft in spots. Not what you want to see.

I get the appeal of going green, but if you’re in an area where storms can roll in with little warning, synthetics are still way more forgiving. They don’t wrinkle up or turn to mush if they get wet for a few days. Felt’s okay for quick jobs or mild climates, but I’d be nervous using anything “biodegradable” unless you’re 100% sure you’ll get it covered right away.

Honestly, until they come up with something that holds up like synthetic but breaks down when you actually want it to, I’m sticking with what works - even if it means feeling a bit guilty about the landfill.

Yeah, I’ve had a similar run-in with the “green” felt stuff. Tried it on my shed, thinking I was doing the planet a favor, but after a few days of drizzle and one good gust, it looked like a soggy tortilla. Had to scramble to get the shingles on before it turned into compost right there on my roof.

I get wanting to be eco-friendly, but honestly, synthetic’s just less stressful if you can’t predict the weather (which, let’s be real, is most of us). I’ve left synthetic underlayment exposed for almost two weeks once - thanks to a surprise family emergency - and it was still flat and solid when I finally got back to it. Felt would’ve been toast.

Only thing I’ll say is synthetic can be a little slippery if you’re up there in the morning dew. Nearly did the splits once - my neighbor still laughs about it. But for holding up under unpredictable skies? I’ll take that trade-off over soggy felt any day.