I get the appeal of synthetic—lighter, easier to handle, and yeah, not a total disaster if it gets wet. But I do wonder about the environmental side of things. Most synthetics are plastic-based, and while they might last longer under shingles, what happens when the roof eventually gets replaced? Felt’s not perfect, but at least it breaks down over time. I’ve also seen some synthetics get brittle after a few years in hot climates... maybe not failing outright, but definitely not as tough as day one. Just makes me question if we’re trading one problem for another.
I hear you on the environmental side—plastic waste is a legit concern. But honestly, I’ve torn off plenty of old felt that was just a soggy mess, and it didn’t really “break down” in any useful way. It just sort of turned to mush and made cleanup a pain. Some of the newer synthetics are actually recyclable, at least in theory, though I don’t know anyone who’s actually recycled them yet. Hot climates are rough on everything, but I’ve seen felt literally bake onto the sheathing too. Not sure there’s a perfect answer here... just tradeoffs depending on what matters most to you.
I get what you’re saying about felt turning to mush—definitely seen that mess myself. But I wonder about the recyclability claims for synthetics. Even if it’s possible, how many local places actually accept them? I’m always weighing cost too, and felt’s usually cheaper upfront, even if it’s not as tough in the long run. Sometimes it feels like you’re just picking your poison depending on what you can afford and how long you plan to stay in the house.
I hear you on the cost factor—felt is definitely easier on the wallet upfront, and if you’re not planning to stick around for decades, it can seem like the obvious choice. But I’ve seen a lot of roofs in my time, and honestly, the difference in how they hold up is pretty striking. Felt just doesn’t bounce back after a few years of heat and moisture cycles. I’ve peeled back shingles on 10-year-old roofs and found felt that’s basically turned to paper mache. Not a great feeling when you’re trying to figure out where that leak is coming from.
The recyclability thing with synthetics is a fair point. Most places don’t have a bin for “roofing underlayment” at the curb, and I doubt many folks are hauling it to a special facility. But here’s the thing: synthetic underlayments tend to last so much longer that you’re not replacing them nearly as often. Less waste overall, even if it’s not technically getting recycled every time. Plus, some brands are starting to use recycled content in their products, which is a step in the right direction.
I get that it feels like picking your poison, but I’d argue that if you can swing the extra cost, synthetics are less of a gamble in the long run. Especially if you’re in a spot with wild weather swings or heavy rain—felt just can’t keep up. I’ve seen synthetic underlayment still holding strong after 15+ years, while felt would’ve needed replacing at least once in that time.
If you’re flipping the house or know you’ll move soon, maybe felt makes sense. But if you’re planning to stay put, or just want to avoid headaches down the road, I’d lean synthetic. It’s one of those things where spending a bit more now can save you a lot of hassle (and maybe money) later. Just my two cents from crawling around too many attics and tearing up too many soggy roofs...
That lines up with what I’ve seen, especially after big storms—felt just doesn’t recover once it’s soaked through a few times. I’m curious, though: has anyone actually had luck with the newer “high-performance” felts? Some of the manufacturers claim they’re more durable, but I haven’t seen much real-world evidence yet. Also, for folks in colder climates, have you noticed any difference in how synthetics handle ice dams compared to felt? That’s been a pain point on a few jobs for me.
