I get what you’re saying about ventilation, but I’ve seen a couple properties where the synthetic underlayment still had issues even after the attic airflow was sorted out. Maybe it’s just our climate (humid summers, cold winters), but felt seemed to handle the temperature swings a bit better in those cases. Anyone else notice synthetic getting brittle after a few years?
I’ve actually seen the opposite in a few projects up here in the northeast.
—I get where you’re coming from, but I’ve pulled up synthetic that was 8-10 years old and it looked almost new, even after some wild freeze/thaw cycles. The trick seems to be which brand you use and how it’s installed. Some of the cheaper synthetics do get brittle, but the higher-end stuff with UV resistance holds up. Felt always seemed to wrinkle or tear on me when things got damp. Maybe it’s just luck of the draw or installer habits...“synthetic underlayment still had issues even after the attic airflow was sorted out”
I had the same debate when I bought my place last year. Pulled up a corner of the roof (don’t ask) and found felt that was basically mush. My roofer swears by “the good synthetic stuff”—he said,
. I guess if you cheap out, it’s a gamble either way, but I’d rather risk brittle than soggy.“the higher-end stuff with UV resistance holds up”
- Had the same dilemma a few years back—my old felt was basically falling apart after 15 years (humid summers here didn’t help).
- Switched to synthetic when I re-roofed. The installer used a higher-end brand with UV protection, and it’s held up great so far—no leaks, no weird smells, even after a couple of nasty storms.
- Only thing: synthetic can get slippery if you’re up there, so heads up if you’re DIY-ing.
- I get the “brittle vs soggy” thing...but honestly, soggy felt was a pain to deal with. Synthetic seems less likely to rot or turn to mush.
- Price was a bit higher, but for me, worth not having to worry about it for a long while.
