Had a house last summer where the seller swore up and down their “premium” shingles were failing because of the brand. Turns out, the attic vents were basically decorative… barely a whisper of airflow. I tell folks, you could put a metal roof on there and it’d still be a sauna underneath. Ventilation’s like socks with shoes—ignore it and you’ll regret it sooner or later.
And yeah, synthetic underlayment’s been a lifesaver around here. I’ve seen felt turn into something that looks like wet tissue paper after just one good storm.
I get where you’re coming from about ventilation being a big deal, but I’m not totally convinced it’s always the main culprit when shingles go bad. I’ve managed a few properties where the attic airflow was less than ideal—think tiny gable vents and not much else—but the shingles still held up for 15+ years. Maybe it’s our milder winters here, or maybe just luck with the batches we got. I do wonder if some brands are more forgiving than others when it comes to poor ventilation.
On the underlayment front, I’m a bit on the fence. Synthetic definitely holds up better in storms, no argument there. But I’ve had a couple of contractors swear that the old-school felt “breathes” better, especially in older houses that weren’t built as tight. One place I look after had synthetic put down, and now there’s this weird musty smell in the attic that wasn’t there before. Coincidence? Maybe. Or maybe it’s trapping more moisture than the felt did. Hard to say without tearing everything up, which isn’t happening anytime soon.
Curious if anyone’s actually seen a difference in shingle lifespan between felt and synthetic, or is it mostly about how well the roof is installed in the first place? Sometimes I think we blame the materials when it’s really just a rushed job or corners cut somewhere else.
Curious if anyone’s actually seen a difference in shingle lifespan between felt and synthetic, or is it mostly about how well the roof is installed in the first place? Sometimes I think we blame the materials when it’s really just a rushed job or corners cut somewhere else.
That’s honestly been my experience too. I keep coming back to installation quality over materials, at least in most of the issues I’ve had to sort out. I’ve seen roofs with basic 15# felt last decades, and others with fancy synthetic underlayment start having problems after a couple years—usually because someone got lazy with flashing or didn’t nail things down right. It’s hard to separate out what’s really the underlayment and what’s just a sloppy install.
The musty attic thing you mentioned is interesting. I had something similar happen after switching to synthetic on an old duplex. The attic never smelled before, but about a year later, there was this damp, stale odor that wouldn’t go away. We checked for leaks, found nothing obvious, but I still wonder if the new underlayment changed how moisture moves up there. Maybe older houses just need that little bit of “breathability” from felt? Or maybe it’s just coincidence and there’s something else going on—hard to say without ripping things apart.
As for ventilation, I’m with you that it gets blamed for everything. Sure, it matters, but I’ve got a couple places with barely any venting (old houses, tiny eaves), and the shingles are still going strong after 18 years. Maybe climate is a big piece of it—hotter places probably see more issues from trapped heat and moisture than somewhere mild.
I do wonder if some brands are just tougher than others when it comes to less-than-ideal conditions. Tamko, CertainTeed, GAF—they all have their loyalists who swear by them in rough situations. But again, maybe that’s more about luck or installer skill than anything else.
It’d be great if there was some way to really know whether synthetic or felt makes a difference long-term...but unless someone wants to fund a 30-year side-by-side test on identical roofs, we’re all kinda guessing based on what we see day-to-day. For now, I’m sticking with “it depends”—on the house, the crew, the weather...and maybe just plain luck sometimes.
I’ve been down the rabbit hole on this since buying my place last year. The roof’s only about 8 years old, but I started noticing a faint musty smell in the attic after a heavy rain, which freaked me out. Turns out, the previous owner had synthetic underlayment put in during a re-roof. No leaks, but I can’t help wondering if it’s trapping more moisture than the old felt would have. I read somewhere that synthetics are less “breathable,” but then again, maybe it’s just my imagination or something else entirely—like you said, hard to know without tearing things apart.
I’ve also heard people swear by CertainTeed or GAF, but my neighbor’s Tamko roof is holding up just as well as mine, and his house is older. He did mention his installer was super picky about flashing and nailing patterns, so maybe that’s the real secret sauce.
Honestly, I’m starting to think installation trumps everything else unless you’re in some extreme climate. Still, I wish there was a way to know for sure if swapping underlayment would actually make a difference or if I’m just chasing ghosts.
That musty smell after rain is all too familiar. I ran into something similar when we redid our roof a few years back—swapped out the old felt for synthetic underlayment because the installer swore by it. No leaks, but I started noticing a damp, almost earthy smell in the attic during humid stretches. At first, I blamed the underlayment, but after poking around, it turned out my soffit vents were half-blocked by insulation. Fixed that up, and the smell mostly disappeared. Sometimes it’s not just the materials, but how the whole system works together.
I get the whole “synthetic is less breathable” argument, but honestly, I think ventilation plays a bigger role than most people realize. You can have the best shingles—Tamko, GAF, whatever—but if the attic can’t vent, moisture’s gonna linger. I’m a big fan of going as green as possible, so if I had to do it again, I’d look at recycled-content underlayments or even metal roofing, but only if the installer actually knows what they’re doing. The pickiest roofer I ever hired was also the one whose work never gave me headaches down the line. Maybe that’s the real trick.
