Anyone else notice aluminum gets these weird white spots if you don’t seal it up right?
Yeah, I’ve seen those spots—happened on my shed roof after I rushed a patch job one rainy weekend. Figured it was just dirt at first, but nope, that chalky stuff stuck around. I ended up sanding it down and using a low-VOC sealant, which helped a bit. Honestly, I’d rather patch than replace unless water’s actually getting in... but prepping is always more work than I think it’ll be.
That chalky white stuff is usually oxidation—aluminum reacts with moisture and air, especially if the sealant’s not solid. I tried just scrubbing it off once, but it came right back. For me, cleaning, then hitting it with a self-etching primer before sealing made a difference. It’s a pain, but if water’s not getting in, I’d stick with patching too. Full replacement only if it starts leaking or corroding through. Prepping always takes longer than you think... but skipping it just means more work later.
That chalky buildup is a classic sign the flashing’s been exposed for a while. I’ve seen folks just paint over it, but honestly, if you don’t get all the oxidation off first, it’ll bubble up again under the paint or sealant. Did you check if the flashing’s still solid underneath? Sometimes it looks worse than it is, but if you can poke through with a screwdriver, that’s when I’d start thinking about replacement. Otherwise, yeah, a good cleaning, primer, and sealant usually buys you a few more years. Just takes patience... and a bit of elbow grease.
if you don’t get all the oxidation off first, it’ll bubble up again under the paint or sealant
Couldn’t agree more—skipping the prep just means you’re back up there in a year, scraping off flaking paint. I’d add, if you’re already putting in the work, consider using a low-VOC primer and sealant. It’s better for your lungs and the runoff won’t mess with your garden beds. I’ve had decent luck with that combo on my own place, and it held up through a couple rough winters.
That’s spot on about the prep work—nothing’s more frustrating than seeing bubbles or peeling after you’ve already spent the time and money. I’ve found that even a little leftover oxidation can mess up the whole job, especially if you’re dealing with older flashing that’s already pitted. I used to think a quick wire brush and rinse would do it, but after a couple of failed attempts, I started using an etching cleaner before priming. It made a noticeable difference.
Low-VOC products are a good call, especially if you’re working in a tight spot or near anything you’re growing. I’ve tried a few brands and, honestly, some of them go on a bit thinner, so you might need an extra coat, but it’s worth it for the peace of mind. If you’re already up there, might as well do it right and not have to mess with it again for a while.
