You nailed it with the “belt and suspenders” bit. I’ve got peel-and-stick just in the valleys and around the chimney, and honestly, that’s where I sleep better at night. Full coverage? I get why folks do it, but unless you’re in hurricane alley or have a super low pitch, it’s a lot of extra cost and hassle for not much gain. I had to patch a section last fall, and man, getting those shingles up without shredding the underlayment was a pain.
Totally agree on synthetic over felt—felt just doesn’t last in humid spots. I used to see it curl up or get soft after a couple summers. Synthetic’s lighter too, which my back appreciates.
Peel-and-stick is great insurance in the right spots, but for most of the roof, synthetic does the job just fine. Sometimes more isn’t always better... just heavier and pricier.
I hear you on the felt—down here in the southeast, I’ve seen it basically melt into mush after a couple of hot, humid summers. Synthetic’s been a game changer for most folks I inspect for, especially when they’re worried about longevity. I do see some people go overboard with peel-and-stick everywhere, but honestly, unless you’ve got ice damming or crazy wind-driven rain, it’s just adding weight and cost. Valleys and penetrations? Absolutely worth it. The rest? Synthetic holds up just fine in most cases. Funny how sometimes “more protection” just means more headaches down the line...
Funny how sometimes “more protection” just means more headaches down the line...
That’s been my experience too. I once managed a place where the previous owner had peel-and-stick everywhere—looked great on paper, but when we had to do repairs, it was a nightmare getting through all those layers. Synthetics have held up better than I expected, especially in our muggy summers. Valleys and penetrations are where I still won’t skimp, though.
I need to replace the original (1988) underlayment on my "S" clay tile roof here in SoCal. So far, the roofers around here are big on peel and stick and some of the old school guys are not comfortable with it and rather go with 2 layers of TU-35 (plus either torch down or peel&stick for the valleys).
Thoughts?
The original underlayment lasted this long and honestly in 2025, I would like to use material to push this closer to a 50yr roof. Is that even feasible?
While I am at this, should I consider a solar powered vented fan on the deck? Currently, it has 674SQin of net free ventilation (required = 475SQIN) by using one gable and two dormers.
Thanks!
If underlayments had a race: which one would cross the finish line last?
I’ve been through a couple roof projects on older clay tile buildings here in LA, and it’s always a toss-up between peel & stick and the double-layer felt crowd. Peel & stick is definitely the new favorite—faster install, less mess, and it really hugs those weird spots around valleys. But I’ve seen some old-school TU-35 jobs still holding up after 30+ years, so I get why some folks swear by it.
Pushing for a 50-year lifespan is ambitious, but not totally out of reach if you’re meticulous about flashing and ventilation. The tiles themselves will last forever, but the underlayment’s always the weak link. If you go peel & stick, make sure it’s rated for high temps—SoCal sun is brutal.
On the vent fan… with your current setup, you’re already over code for ventilation. A solar fan might help on those crazy hot days, but honestly, unless you’re seeing heat buildup or moisture issues in the attic, it might just be another gadget to maintain. I’d probably put that money toward better underlayment or flashing details instead.
Curious to see what you end up choosing—roofing debates never get old around here...