Sometimes simple just works.
That’s been my motto for years, honestly. I went with felt too—mainly because my dad swore by it and, well, he was usually right about this stuff. But I keep hearing folks rave about synthetic being lighter and easier to install. Anyone actually notice a difference with heat in the attic or is that just marketing fluff?
I’ve wondered about the heat thing too. My neighbor switched to synthetic last year and swears his attic feels cooler, but I’m not sure if that’s just because he finally added some insulation up there. I’ve only ever used felt—old habits die hard, I guess. Anyone notice if synthetic actually holds up better after a few years, especially in places with wild temperature swings?
I’ve seen a lot of claims about synthetic underlayment making attics cooler, but honestly, most of the time it’s the insulation or ventilation doing the heavy lifting there. Synthetic does tend to resist tearing and UV damage better than felt, especially if your roof sits exposed for a while before shingles go on. But in places where temps swing from freezing to blazing hot, I’ve noticed some synthetics can get brittle over time—depends a lot on the brand and thickness. Has anyone actually pulled up old synthetic after 5+ years to see how it compares to felt in real-world conditions? I’m curious if the adhesives or coatings start to break down with all that expansion and contraction...
I’m right there with you on the insulation and ventilation being the real game changers for attic temps. I’ve heard the same marketing pitch about synthetics keeping things cooler, but honestly, I think that’s a stretch. What I do like about synthetic is how much easier it is to work with—lighter, less messy, and it doesn’t wrinkle up like felt if it gets damp before shingles go on.
But yeah, the long-term durability is still kind of a question mark for me too. My neighbor had his roof redone about six years ago with synthetic (not sure which brand), and when he had a small section opened up after a tree limb fell, the underlayment looked fine—no cracking or peeling. That said, we’re in a milder climate, so maybe not the best test case.
I get what you’re saying about brittleness in extreme temps. Some of the cheaper synthetics feel almost plasticky and I’d worry about them getting brittle after years of freeze/thaw cycles. Felt isn’t perfect either though—it can dry out and turn to dust if there’s any moisture intrusion. Honestly, I wish there was more real-world data out there instead of just manufacturer claims...