- Indoors, I’ll admit I’ve used cheaper acrylic caulk for baseboards or trim and it’s held up fine. But for anything exposed to moisture, like kitchens or baths, I stick with better stuff—learned the hard way after mold popped up behind a sink.
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Been there. Winter’s brutal on shortcuts.“One year I patched my flashing with bargain caulk and by spring, it had shrunk and cracked... total waste of time.”
- For flashing, I lean toward polyurethane. It flexes more with temp swings. Silicone’s good too, but doesn’t always stick to metal as well unless prepped right.
- Brand-wise, Sika and OSI Quad have lasted best for me. DAP can be hit or miss outdoors.
- Too many options at the store... I just look for “exterior,” “flexible,” and “UV resistant” on the label now. Saves headaches later.
- Polyurethane’s definitely my go-to for flashing, too. Had a buddy use regular silicone last fall—peeled right off after a couple storms.
- Sika’s solid, but I’ve had mixed luck with Quad in cold snaps (seemed to stiffen up more than I’d like). Anyone else notice that?
- Cheap caulk’s fine for quick fixes indoors, but outdoors it’s just asking for leaks... especially if snow piles up.
- UV-resistant label matters way more than I thought—learned that after some yellowing and cracking showed up mid-summer.
- Prep’s half the battle. Even the best stuff won’t bond if the metal’s dirty or damp.
Prep’s half the battle. Even the best stuff won’t bond if the metal’s dirty or damp.
Couldn’t agree more—surface prep gets overlooked way too often. I’ve seen plenty of so-called “failures” that were really just due to skipping that step. Curious, though: for those dealing with older aluminum flashing that’s oxidized or pitted, are you sanding it down before sealing, or just cleaning? I’ve noticed adhesion can be hit or miss if there’s any corrosion left behind. Wondering if anyone’s had luck with primers, or is that overkill for most repairs?
I’m right there with you—skipping prep is just asking for trouble down the line. With old aluminum, I usually give it a quick sanding if there’s any sign of pitting or white powdery stuff. Just cleaning never seemed to cut it for me, especially if I want the sealant to actually stick. I’ve tried a metal primer once or twice, but honestly, unless it’s a big patch or really rough, I feel like it’s more work than it’s worth. A little elbow grease with sandpaper and a good wipe-down has held up fine on my shed roof so far.
That’s pretty much my experience too—if you skip the sanding or don’t get rid of that oxidation, you’re just setting yourself up for leaks later. I’ve seen a few folks try to shortcut with just a wipe-down and sealant, but it never seems to last more than a season or two, especially if there’s any chalky residue left. The primer thing is interesting though. I’ve used it on some commercial properties where the flashing was really corroded, but for most small repairs, it does feel like overkill. The extra step adds time and cost, and honestly, I haven’t noticed a huge difference in adhesion unless the surface was in rough shape to begin with.
One thing I’m curious about—has anyone tried those self-adhesive flashing tapes as a quick fix? I’ve seen mixed results. On a flat roof section, I used one as a temporary patch and it held up surprisingly well through a winter, but I wouldn’t trust it as a long-term solution. Still, for something like a shed or a spot that’s hard to reach, it might be worth considering.
Also, I’ve noticed that in coastal areas, the salt air seems to eat away at aluminum a lot faster. I manage a few properties near the water, and even with regular maintenance, the flashing gets pitted and powdery way sooner than inland. Anyone else dealing with that kind of accelerated corrosion? I’m always looking for ways to extend the life of the material without having to do a full replacement every few years. Maybe there’s a coating or sealant out there that actually helps in salty environments, but I haven’t found one that really makes a difference yet.
Curious if folks are seeing similar issues, or if it’s just the price you pay for living near the ocean...
