Felt’s like that old friend who shows up when you’re broke—reliable until it rains sideways. I’ve seen more than a few jobs where the felt just gave up after a storm or two, especially if the shingles didn’t go on right away. Synthetic’s definitely grippier and shrugs off rain better, but I’ve had it flap around if the wind picks up and it’s not fastened down well. Honestly, nothing’s perfect, but I’d take the synthetic over a tarp any day... unless you’re into blue roofs, I guess.
I’ve always wondered if felt would even make it halfway around the track if we’re talking about a real race. Every time I’ve had to patch up with felt, it’s like a countdown until the first gust of wind or sideways rain. But then, with synthetic, I’ve seen it bunch up if you don’t get enough cap nails in, especially on steeper slopes. Has anyone actually had synthetic last more than a couple weeks uncovered, or is that just marketing hype? I’m still trying to figure out which one’s less of a headache when you’re stuck waiting on shingles.
Felt’s like that friend who promises to help you move, then bails when it starts raining. I’ve had it blow off in a light breeze—super annoying. But yeah, synthetic isn’t perfect either. I left some uncovered for almost a month (thanks, backordered shingles) and it held up, but only because I went wild with cap nails. Still, I’d pick synthetic for less stress if you’re stuck waiting... just budget for extra fasteners.
I get the frustration with felt, especially if you’re dealing with unpredictable weather. But honestly, I’ve had just as many headaches with synthetic underlayment, especially on bigger commercial jobs. The wind resistance is better, sure, but only if you’re using a ton of fasteners and making sure every seam is tight. I’ve seen crews get a little too confident with synthetic, thinking it’s bulletproof, and then a gust comes through and half the sheet’s flapping around. That’s a nightmare when you’re managing multiple units and trying to keep everything on schedule.
One thing I don’t see mentioned much is self-adhered underlayment. It’s pricier, but for projects where you know the roof might sit exposed for a while—like when you’re juggling trades or waiting on inspections—it’s been a lifesaver. No worries about wind, and it actually seals around the nails. Downside is it’s a pain to reposition once it’s down, and in hot weather it can get messy, but I’ll take that over chasing blown-off sheets across a parking lot.
I’m in the Midwest, so we get everything from heavy rain to high winds to snow. For steep slopes, synthetic’s fine if you’re diligent with fasteners. On low-slope or flat roofs, though, I’d rather pay extra for something that’s not going to move at all. And honestly, if you’re dealing with insurance claims or warranty issues later, having documentation that you used a higher-grade underlayment can save a lot of back-and-forth.
Felt’s cheap and easy, but I only use it now if I know the shingles are going on the same day. Otherwise, it’s just not worth the risk or the callbacks. Synthetic’s a step up, but it’s not set-and-forget either. Just depends how much hassle you want to deal with if the weather turns on you.
Last summer I got my first real taste of what happens when you trust felt for too long. We had a couple days of pop-up storms in the forecast, but the plan was to finish shingling before anything rolled in. Of course, nothing went as planned—half the tear-off was done when the sky turned black. We scrambled to get the felt down, but by morning, water had seeped through where it wrinkled up and pooled. The callbacks after that weren’t fun.
Lately, I’ve been helping out on jobs where they use synthetic. It’s way lighter to carry up a ladder, which is a win for me, but I’ve noticed if you don’t put enough cap nails or staples, it’ll catch wind and start flapping. One guy on our crew thought he could just tack it every few feet—bad idea. We spent an hour chasing it across a neighbor’s yard.
Self-adhered stuff is expensive, like you said, but when we used it on a complicated dormer job last fall, it stuck tight even when we got hit with a windstorm overnight. It’s sticky as heck if you mess up your line, but at least nothing blew off. If I had to pick the slowpoke in this “race,” felt would be dragging way behind... especially on days where weather’s unpredictable.
