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

- Had the same debate last year. Ended up going with synthetic, even though it cost more.
- My old roof (asphalt shingles, Midwest climate) had felt for 25+ years. It did its job, but I noticed it started to wrinkle and break down under a few leaks.
- Synthetic’s lighter and way easier to handle, especially on steeper slopes. Didn’t tear as easily when I was crawling around up there.
- Yeah, felt can last ages if installed perfectly, but I’ve seen it fail early after a bad storm or two.
- Honestly, if you’re planning to stay in the house long-term, that extra cost for synthetic might be worth it... less landfill waste too.

Had the same dilemma when I replaced my roof a few years back (asphalt shingles, northern Illinois). Ended up going with synthetic too. The weight difference alone made a huge difference - felt was always a pain to haul up the ladder, especially on windy days. One thing I noticed: after a couple of rough winters, the synthetic didn’t show any of the bubbling or tearing I used to see with felt. That said, if you’re on a tight budget and your roof isn’t super steep, felt can still do the job... just gotta keep an eye out for leaks and fix them quick.

I get the appeal of synthetic, but I’ve seen a few jobs where it actually got slippery as heck when wet - made repairs a pain. Felt might not last as long, but sometimes it’s just easier to patch up if you spot an issue early. Guess it’s a trade-off, especially with all the freeze-thaw cycles up here.

That slippery synthetic is no joke - nearly wiped out trying to patch a spot after a rainstorm last fall. I do like that it’s lighter and goes down faster, but I’m with you: felt’s easier to cut and patch, especially when you’re up there solo. Ever notice if the synthetic gets brittle after a couple winters? I’ve only used it on one shed so far, so not much long-term data yet...

Yeah, that synthetic stuff is like trying to walk on a greased-up slip’n’slide - ask my bruised ego from last summer. I’ve had it on my garage roof for about three years now, and honestly, it’s holding up okay, but I do notice it feels stiffer than when I first put it down. Not cracking yet, but I’m in the Midwest, so we get those freeze-thaw cycles. Felt always seemed more forgiving if you had to patch or overlap. Synthetic’s lighter, sure, but sometimes I miss the old-school stuff when I’m up there cursing at the wind.