Yeah, nail spacing gets skipped a lot—seen it way too many times on jobsites. Even with synthetic, if the fasteners are off, you’re just asking for trouble when the wind picks up. I’ve mostly worked with architectural shingles, but I’m seeing more folks try metal lately. Anyone notice if synthetic underlayment holds up better under metal roofs versus asphalt? I’ve heard mixed things, especially in humid spots.
I’ve seen synthetic underlayment hold up better under metal, but only if the install’s done right—especially in humid areas. Metal roofs can trap more heat and moisture underneath, so if the synthetic isn’t high quality or it’s not sealed well, you’ll get curling or even mold. I’ve had a couple properties where the felt just disintegrated after a few years under metal, but synthetic lasted longer. Curious if anyone’s had issues with condensation buildup under metal when using synthetic? That’s been a headache for me in the Southeast.
- Just did my first roof (metal, Florida—humidity’s a hobby here)
- Went with synthetic, but installer kinda rushed it... now I’ve got some weird sweating in the attic corners
- No mold yet, but I keep checking like a paranoid raccoon
- Felt looked ancient when we pulled it off, just crumbled—synthetic’s holding up better so far, but man, that moisture is sneaky
Synthetic’s definitely tougher than old-school felt, especially in Florida’s swampy air. But if the install gets rushed or ventilation’s off, you’ll get attic sweat no matter what’s under there. I see this all the time—metal roofs trap heat, and without good airflow, moisture just hangs around. Synthetic buys you time, but it won’t fix bad venting. Might be worth checking your soffit and ridge vents... sometimes installers skip details when they’re in a hurry.
