Still, if you don’t tack it down right, even the fanciest stuff will flap like a flag in a storm... learned that the hard way.
That’s the truth—doesn’t matter how high-end the underlayment is, if it’s not fastened well, wind’ll find a way to mess with it. I’ve seen synthetic hold up better than felt in most cases, but I’ve also had a roll of “premium” synthetic tear loose because someone got lazy with the cap nails.
I’m curious—has anyone here actually used those self-adhered ice & water membranes as a full underlayment? I know they’re overkill for most jobs and cost a fortune, but I did one low-slope porch with it last year and it was basically bulletproof. Only downside was getting it straight on a hot day... once it sticks, there’s no going back. Wondering if anyone’s run into issues with breathability or trapped moisture when using peel-and-stick everywhere?
I’ve seen a few full-coverage ice & water jobs, usually after major leaks or on really shallow pitches. Haven’t run into breathability issues myself, but I do wonder about long-term moisture if there’s any trapped humidity in the decking. Anyone notice decking rot under peel-and-stick after a few years? That’s my main concern—especially in places with big temp swings.
Peel-and-stick underlayment is like that friend who means well but sometimes overstays their welcome. I’ve seen it do wonders after hailstorms—keeps the water out, sure, but if your decking’s even a little damp when it goes down, you’re basically shrink-wrapping the problem. Couple years later, you might peel it back and find that weird black rot creeping in, especially if you’re in a place with wild temp swings. Minnesota roofs, for example... yikes.
I get why folks go full-coverage on shallow pitches or after leaks—it’s peace of mind when you’re staring down another thunderstorm. But I’m always a little twitchy about breathability. If the roof can’t “exhale,” that trapped moisture just sits there, plotting its revenge.
I’ve had better luck with hybrid setups—ice & water on eaves/valleys, then synthetic up top. Costs a bit more time, but at least the wood can dry out if it needs to. Not saying peel-and-stick is evil, but if there’s even a hint of moisture in your decking? Might wanna think twice before sealing it up tight.
That’s exactly why I get nervous about peel-and-stick on the whole roof, especially in places with wild humidity swings. I’ve seen a neighbor’s deck go soft after just a few years—looked fine from the outside, but underneath? Mush city. I’m a big fan of letting things breathe, even if it means a little more work up front. Anyone tried those newer “breathable” membranes? Curious if they actually help or if it’s just marketing.
Breathable membranes aren’t just marketing fluff—at least, not all of them. I’ve been following the green building crowd for a while, and there’s real science behind letting a roof assembly dry out. The old-school peel-and-stick stuff is basically wrapping your roof deck in a plastic bag. Sure, it keeps water out, but if anything gets in (and something always does, eventually), it’s stuck there. That’s how you get mushy decks and mold.
I put a “vapor-open” underlayment on my own place a few years back—steep metal roof, humid summers, cold winters. It wasn’t cheap, but I wanted to see if it lived up to the hype. So far, zero issues with condensation or rot. I actually cut a test hole last fall and the wood looked and smelled fresh, which is more than I can say for the old felt I tore off (that stuff was nasty).
Not all breathable membranes are created equal, though. Some are just glorified housewraps, and they’ll tear if you look at them funny. The better ones have real perm ratings and can handle foot traffic during install. You’ve got to watch the details—if you go breathable but then slap ice-and-water shield everywhere, you’re back to square one.
I get why folks like peel-and-stick for the “set it and forget it” factor, but if you care about longevity and you’re in a climate that swings between damp and dry, letting the roof assembly breathe makes a ton of sense. It’s more work upfront—flashing details matter, and you can’t just rely on sticky sheets to bail you out—but it pays off in the long run.
Bottom line: breathable underlayments aren’t a gimmick, but you’ve got to do your homework on which one you pick and how you install it. If you want a roof that lasts more than a decade without hidden surprises, it’s worth considering.
