That’s a good point about warranties—I hadn’t really thought about how an overlay might limit coverage down the road. We’re in central Illinois, so the freeze/thaw thing is real. I’m leaning toward a tear-off for peace of mind, but I keep getting conflicting advice from contractors. Some say my decking looks fine from the attic, others warn there could be hidden issues you won’t see until the shingles come off.
One thing I’m not sure about: if you do go for a full tear-off, is it worth upgrading to synthetic underlayment instead of regular felt? I’ve read mixed things—some say it’s overkill unless you have a low slope, others swear by it for moisture protection. Anyone here actually notice a difference? Just trying to figure out what’s worth the extra cost and what’s just marketing.
One thing I’m not sure about: if you do go for a full tear-off, is it worth upgrading to synthetic underlayment instead of regular felt?
Honestly, I’ve seen both hold up fine, but synthetic definitely sheds water better if you get caught mid-job by a surprise storm. Around here, with all the freeze/thaw cycles, moisture sneaking in is what kills roofs early. Felt’s been around forever and works, but it tears easier and can wrinkle up if it gets wet. Synthetic’s not magic, but it’s tougher. I wouldn’t call it overkill—more like cheap insurance, especially if you’re already paying for a tear-off. Just my two cents.
Synthetic’s not magic, but it’s tougher. I wouldn’t call it overkill—more like cheap insurance, especially if you’re already paying for a tear-off.
That’s pretty much how I see it too. The extra durability is nice, especially if you’re in a spot where weather can turn fast. One thing I’m curious about—has anyone noticed a difference in attic temps or ventilation after switching to synthetic? I’ve read some brands claim better breathability, but I’m not sure how much that matters in real-world use.
I switched to synthetic underlayment when I did a full tear-off last year (asphalt shingles, Midwest climate). Honestly, I haven’t noticed a big difference in attic temps—maybe a couple degrees at most, but nothing major. My attic vents are the same as before. The main thing I did notice was during installation: the synthetic stuff was way easier to walk on, even when it got damp. As for breathability, I’m still skeptical. The marketing makes it sound like a game-changer, but in practice, I think proper ventilation matters more than what’s under the shingles.
I did a full tear-off about five years ago—also Midwest, and also asphalt shingles. I went with synthetic underlayment too, mainly because the installer swore up and down it was safer and more durable than the old felt. Like you, I didn’t see any real change in attic temps. Maybe a degree or two, but nothing that made a difference to my heating or cooling bills. I think a lot of the “breathability” claims are just marketing noise, honestly.
One thing I did notice: when we pulled off the old layers (there were two), there was some hidden rot around a couple of vent pipes that I never would’ve spotted if I’d just added another layer. That alone made the tear-off worth it for me. Plus, the roof looks flatter—no weird bumps or waves from stacking shingles.
The only real downside was the mess and cost. Full tear-off took longer and generated a ton of debris. Felt like every nail ever driven into that roof ended up in my yard. But long-term, I’m glad I went that route. The warranty’s better, and I don’t have to worry about weight issues or covering up problems.
I get why people just add a new layer—it’s cheaper and less hassle up front. But after seeing what was lurking under my old shingles, I’d be nervous about skipping the tear-off, especially on an older house. Ventilation still seems like the bigger deal for attic temps anyway... underlayment is more about install convenience and maybe durability if you get a leak.
Curious if anyone’s actually had issues with synthetic underlayment breaking down over time? Mine still looks fine from what I can see, but it hasn’t been that long yet.
