I’m right there with you on the old rolled roofs—mine’s probably pushing 25 years and every time I’m up there, I feel like I’m tiptoeing through a minefield. The binocular trick is handy for the obvious stuff, but I get what you mean about missing the subtle dips or soft spots, especially after a heavy rain.
On the liquid-applied membranes, I’ve tried two brands for patching around my chimney and a skylight. Prep seems to make or break it. The first time, I just brushed off the area and slapped it on—peeled within six months. Second go-around, I scrubbed with a wire brush, let it dry out for a day, then primed before applying. That patch is still holding after two winters (I’m in upstate NY, so lots of freeze-thaw). Not sure if it’s brand or just better prep.
Mesh tape plus elastomeric has worked okay for me too, but like you said, nothing lasts as long as you’d hope. At this point, I just plan on checking every spring and fall... seems like that’s the only way to stay ahead of leaks.
Spotting Wear and Tear on Used Gear: My Quick Routine
That’s pretty much my approach too—if I don’t check things every spring and fall, I end up with a surprise leak or two. I had a similar situation with liquid membranes. The first time I used one (can’t remember the brand, but it was whatever the local hardware store had), I just cleaned off the moss and slapped it on. Looked great at first, but by the next rainy season, it was already bubbling up around the edges. Learned my lesson there.
Now, I’m borderline obsessive about prep. I’ll sweep, wire brush, and sometimes even hit stubborn spots with a little acetone if there’s any oil or sap. Let it dry out for a day or two—hard to do in the fall when everything’s damp, but worth it. Then I use primer if the instructions call for it (some brands seem to skip that step, but I think it helps). Since then, my patches have held up much better—though like you said, nothing’s permanent on these old roofs.
One thing I started doing after a buddy suggested it: when I’m up there after a rain, I’ll gently press around with my foot to feel for soft spots. It’s not exactly scientific, but sometimes you can catch an area that looks fine but feels spongy underfoot. That’s usually where water’s been sneaking in under the surface.
I’ve also tried mesh tape with elastomeric around seams and vents. It works okay for a couple years, but eventually the sun gets to it and things start cracking again. Upstate NY winters are brutal—freeze-thaw cycles just tear everything apart.
Honestly, at this point, my philosophy is to patch what I can and keep an eye out for trouble spots before they get worse. Full replacement is probably in my future, but as long as these patches keep holding through another winter or two, I’ll count that as a win... at least until the next big storm rolls through.
That foot-test for soft spots is underrated—I've found a few hidden trouble areas that way too. One thing I’d add: if you’re seeing bubbling on those membranes, it’s usually a sign moisture was trapped underneath. Sometimes even a day or two of drying isn’t enough, especially in the fall. I’ll use a leaf blower to speed things up if I have to. Those freeze-thaw cycles up here really are relentless... patch jobs that last two years feel like a win in my book too.
Those freeze-thaw cycles up here really are relentless... patch jobs that last two years feel like a win in my book too.
I hear you on the freeze-thaw. I’ve noticed sometimes even after using a blower, there’s still residual dampness under the membrane, especially if the decking’s older. Have you ever tried using moisture meters to check before sealing things up? Wondering if it’s worth the extra step or just overkill for small repairs.