I actually asked about that when we had our roof done last fall. Our contractor used cap nails on the synthetic, said it holds up better in wind than staples, especially since we get those crazy gusts off the lake. I’ve heard some folks say staples are fine if you use enough, but I wasn’t convinced. Has anyone noticed a difference in noise or leaks between felt and synthetic? Ours seems quieter during rain, but maybe that’s just me.
We had a similar debate at our place when we re-roofed a couple years back—our old felt underlayment was a mess after one bad winter, so I figured synthetic had to be worth a shot. Ended up going with synthetic and cap nails too, mostly because my neighbor’s roof actually lost a chunk of felt after a big storm (he’d used staples). Haven’t had any leaks since, and honestly, I think the noise is less noticeable during heavy rain compared to the old felt. Could just be my imagination, but it does feel quieter.
One thing I did notice: when we walked on the roof before the shingles went down, the synthetic seemed a lot less “crunchy” than felt. Maybe that’s why it sounds different in the rain? I’m curious if anyone’s seen how these synthetics hold up after 10-15 years—does it break down under shingles over time, or is it really as tough as they claim?
I’ve torn off a few roofs with synthetic underlayment that were 12-15 years old, and honestly, most of them looked almost new under the shingles—no weird brittleness or tearing like felt gets. That being said, I’ve seen some cheaper synthetics start to curl or get brittle if there’s a leak and water sits on them for months. The higher-end stuff seems to hold up better. Haven’t seen one totally fail yet, but I’d be curious what happens at the 20-year mark... might depend on how much sun sneaks in around the edges too.
I’ve seen the same thing with synthetics—they usually look way better than old felt, even after a decade or more. But I agree, the cheap stuff can go downhill fast if it gets wet. Around here (lots of sun), edges are always the first to go. Sometimes you’ll see shrinkage or curling where the underlayment’s exposed, especially if the drip edge isn’t tight. I’m curious too what 20+ years will look like... shingles usually give up first anyway.
I get where you’re coming from, but I’ve actually seen some of the newer high-temp felt underlayments hold up surprisingly well, even in spots with a lot of sun exposure. Synthetic does look cleaner, but if you’ve got a tight drip edge and good overlap, quality felt can still go the distance. The real killer seems to be improper installation—once water gets underneath, it doesn’t matter what you used. Edges and valleys always tell the story first...