finally found an underlayment that lasts—what's your experience?

I get what you’re saying about synthetic lasting longer, but honestly, I’ve found felt way easier to work with, especially on steep pitches. Those synthetic rolls are so slippery—almost wiped out last fall. Maybe it’s just what you get used to, but I’d rather swap out felt every few years than risk a fall.

Those synthetic rolls are so slippery—almost wiped out last fall.

That’s exactly what I ran into. First time up on my roof, I went with synthetic because everyone said it’d last longer and was “the new standard.” But man, on a 7/12 pitch, it felt like walking on ice in sneakers. I ended up crawling more than standing, and I’m not even scared of heights. Ended up with bruises just from sliding around.

Here’s what worked for me after that mess:

1. Tried felt the next time—way easier to get a grip, especially when you’re carrying tools or a bundle of shingles. It’s heavier, but at least you don’t feel like you’re about to take a ride off the edge.
2. For steep pitches, I started using toe boards (just 2x4s nailed in temporarily). Makes a world of difference no matter what underlayment you use, but especially with synthetic.
3. If you do stick with synthetic, those roofing shoes with sticky soles help a bit, but honestly, nothing beats the felt for traction.

I get why people like synthetic—my neighbor swears by it since he had a leak with felt after just five years. But for me, not worth the risk of falling. Maybe if I had a flatter roof or was hiring pros, I’d think differently.

One thing I noticed: after two summers and a couple storms, the felt did start to look rough in spots. But replacing it wasn’t as bad as I thought—just pulled up the old stuff and rolled out new in an afternoon.

Guess it comes down to what you’re comfortable with. I’d rather do a little extra maintenance than end up in the ER. If anyone’s doing their own roof and worried about slipping, felt’s definitely easier to handle... at least that’s been my experience so far.

- Totally agree about the toe boards—makes a huge difference, especially on anything steeper than a 6/12.
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“I’d rather do a little extra maintenance than end up in the ER.”

Toe boards are a game changer, no question. I’ve seen too many folks get a little too confident on a steep pitch and end up regretting it—sometimes in the ER, sometimes just with a bruised ego. I’m always telling people, you can’t put a price on safety, even if it means a bit more time setting things up.

On the underlayment side, I’ve noticed a pretty big difference between synthetics and the old-school felt, especially under metal roofs. Synthetics seem to hold up better to foot traffic and don’t tear as easily when you’re dragging panels around. That said, I’ve had a couple of jobs where the synthetic got slick as ice when there was morning dew or a light rain. Not fun. Felt isn’t perfect either, but at least you know what you’re getting—just have to watch for it wrinkling or tearing if you’re not careful.

Durability-wise, the synthetics win out for me, especially in places with wild temperature swings. I’m in the Midwest, so we get everything from blazing sun to ice storms. The felt just doesn’t last as long under those conditions, especially if the roofers can’t get the metal on right away. But traction is hit or miss depending on the brand. Some of the cheaper synthetics are downright dangerous when wet.

One thing I’ve run into with metal roofs is condensation issues if the underlayment isn’t up to snuff. Had a barn where they used bargain-basement synthetic and it started breaking down after just a couple years—ended up with leaks and mold in the attic. Not fun to explain that one to the owner.

I’d say if you’re working with metal, spend the extra for a good synthetic, but don’t assume they’re all created equal. And always check how grippy it is before you start walking around up there. Sometimes I wish manufacturers would actually test these things in real-world conditions instead of just slapping “high traction” on the label.

Curious if anyone’s found a synthetic that actually stays grippy when wet? That’s been my biggest gripe so far...

Sometimes I wish manufacturers would actually test these things in real-world conditions instead of just slapping “high traction” on the label.

That’s exactly what I was thinking when I started looking into underlayment for our place. I’m in the Northeast, so we get a lot of freeze/thaw and random rain, and I was surprised how much the “high traction” stuff can still feel like a slip-n-slide if there’s any moisture. I went with a synthetic (I think it was Titanium UDL30?) because the roofer swore by it, but even then, he was super cautious about working early mornings or after a drizzle.

Here’s what I learned step-by-step:
1. Ask to see a sample before they install—actually touch it, maybe even pour a little water on it if you can.
2. Check the warranty and see if it covers breakdown from condensation or UV exposure. Some of the cheaper rolls don’t.
3. If you’re DIY-ing, lay out toe boards or roof jacks, even if it feels like overkill. The one time I didn’t, I nearly slid off the porch roof.

I agree synthetics last longer, but I wish there was a better way to know which ones are safe when wet. It’s kind of trial and error, which is nerve-wracking when you’re up there.