If underlayments could talk: which one would outlast the others?

Has anyone tried any of those newer “biodegradable” options? Or is that just greenwashing?

I get what you mean about the eco side. I was tempted by the “green” underlayments too, but honestly, I’m a bit skeptical. My neighbor went with one of those biodegradable types on his garage roof last year - he wanted to feel better about the landfill thing. It did go down easy and didn’t have that chemical smell, but he’s already seeing some weird curling at the edges after our last wet spring. Not sure if it’s a fluke or just early days, but it made me pause.

I know synthetic isn’t perfect for the environment, but in my case (asphalt shingles, Midwest winters), I’d rather not risk leaks or early failures just yet. Maybe in a few years these eco options will catch up, but right now it feels like a bit of a gamble. Sometimes “green” labels don’t mean much if you have to redo the whole job sooner…

- Used a plant-based underlayment on my shed roof last fall (Pacific NW, lots of rain).
- Install was smooth, no strong odors, and it felt solid underfoot.
- After a brutal winter, it’s holding up fine - no curling or leaks so far.
- I do wonder about long-term durability, though. Some brands seem more robust than others.
- Honestly, I get the hesitation. If it fails early, that’s not very “green” either... but tech’s moving fast.
- For smaller projects or lower-risk spots, I’d try eco options again. Main house? Still on the fence.

I get the hesitation on using plant-based underlayments for bigger projects. I put down a recycled-fiber one on my garage last year - rainy Oregon coast, so similar climate - and it’s still looking good.

“If it fails early, that’s not very ‘green’ either...”

That’s exactly the dilemma I keep running into. The recycled-fiber stuff is tempting, especially with the sustainability angle, but I’ve seen a couple jobs where early breakdown led to leaks - and then you’re right back to square one, with more waste. Has anyone here actually seen a plant-based underlayment hold up past five years in a wet climate? I’m still leaning toward synthetics for anything critical. Maybe it’s just risk tolerance, but I’d rather not gamble on my main building roofs yet...

I hear you on the risk side - nobody wants to be the guinea pig on a big roof. I actually tried a cellulose-based underlayment on a detached garage about six years ago (Pacific Northwest, so plenty of rain), mostly because I wanted to see how it’d handle our winters. It’s still holding up, but I do see some fraying at the edges where the drip line is. No leaks yet, but I’m not sure I’d trust it for a main house, especially with a low pitch.

What’s interesting is that the installer said the key was making sure the ventilation was dialed in - apparently, moisture from inside can be as much of a problem as rain from above. I wonder if that’s why some of these “green” options fail early? Maybe it’s less about the material and more about how it’s installed and what kind of roof it’s on.

Has anyone tried mixing materials - like plant-based underlayment for most of the roof, but synthetic in the valleys and eaves? Or is that just asking for trouble down the line...