That attic heat trap thing is so real—my place is a 1950s ranch, and before I beefed up the insulation, it was like living under a broiler in July. I totally get what you’re saying about underlayment not really making a dent in cooling costs. I used to think a fancy underlayment would help with summer heat, but honestly, after crawling around up there with a staple gun and a headlamp, it was the insulation (and air sealing all those weird gaps around the chimney) that actually made the house feel less like a sauna.
That said, I do think underlayment earns its keep during our freeze-thaw cycles. We had a nasty ice dam year a while back, and the folks down the street with just old felt underlayment got leaks, while my newer synthetic stuff held up. But for the day-to-day comfort and utility bills? Insulation’s the MVP. And yeah, my back still remembers those insulation rolls—who knew they’d be heavier than they look?
Interesting you mention the difference with synthetic underlayment—I’ve only ever used the old asphalt felt, and it’s never been great during those freeze-thaw cycles. I’ve patched a couple leaks near the eaves after rough winters. Did you notice any difference in install time or difficulty with the synthetic stuff? I’ve heard it’s lighter but can get slippery. Wondering if it’s worth switching next time I redo the roof, or if just bumping up the insulation even more would make a bigger impact overall.
Did you notice any difference in install time or difficulty with the synthetic stuff? I’ve heard it’s lighter but can get slippery. Wondering if it’s worth switching next time I redo the roof, or if just bumping up the insulation even more would make a bigger impact overall.
I get where you’re coming from. I used the old felt for years too, mostly because that’s what my dad always did, and I figured why mess with it. But after the last time I had to patch a leak in February (not fun, by the way), I finally tried the synthetic underlayment when we did the garage roof.
Honestly, it went on way faster. It’s way lighter—like carrying a roll of wrapping paper compared to those heavy felt rolls. Didn’t kill my back. But yeah, it’s slick if you’re not careful. We had a dry day and it was still kind of like walking on a tarp. My brother nearly went off the edge, so if you go that route, definitely watch your step or get those grippy boots.
As far as performance, the synthetic stuff seems to hold up better through the wild temperature swings. No weird bubbling or tearing like the felt used to get after a few months. Haven’t noticed any leaks yet, but it’s only been two winters so far.
On insulation—if your attic is drafty or you’re getting ice dams, adding more up there probably helps more with the freeze-thaw problems than just swapping underlayment. But if you’re already pretty well insulated and still getting leaks at the eaves, I’d say the synthetic underlayment is worth a shot. Price isn’t that much more, at least where I am. For me, the time saved and not having to wrestle with soggy felt was worth a little extra.
If you’re on a tight budget, maybe just do the synthetic on the problem spots (like eaves and valleys) and stick with felt everywhere else. That’s what my neighbor did and he seems happy enough. Just my two cents.
For me, the time saved and not having to wrestle with soggy felt was worth a little extra.
Interesting point about the insulation—have you ever had issues with condensation in the attic after switching underlayments? I’ve heard stories about synthetic stuff being less “breathable” than felt, but not sure if that’s just old-school thinking or if it actually matters.
I get where you’re coming from—there’s definitely some debate about synthetic underlayments and attic moisture. I’ve seen a lot of homes with synthetics and, honestly, if the attic’s got proper ventilation, condensation usually isn’t a problem. Sometimes people blame the underlayment when it’s really blocked soffit vents or not enough airflow. Old-school felt does breathe a bit more, but I haven’t noticed major issues unless something else was off. If your attic’s dry now, you’re probably in good shape.
