Been there myself—thought I'd save a quick buck patching up flashing with sealant. It looked good at first, but after one winter... well, let's just say water finds every shortcut we take. Doing it right usually saves headaches down the road.
"water finds every shortcut we take"
Yep, learned this lesson early on... sealants are temporary at best. Aluminum flashing expands and contracts quite a bit with temperature swings, so even the best sealant eventually cracks. Curious—did you notice corrosion or just sealant failure?
"Curious—did you notice corrosion or just sealant failure?"
Yeah, good question. In my experience, it's usually the sealant that goes first, especially if there's a lot of temperature fluctuation. Aluminum flashing moves more than most people realize, and even the "premium" sealants eventually lose their flexibility and crack. Corrosion can happen too, but that's usually more obvious—white powdery residue, discoloration, or even pitting.
If you're seeing mostly sealant failure, you might try switching to a flexible flashing tape or membrane underneath. I've had pretty good luck with those. They stretch and move with the metal better than caulk or sealant alone. Also, if you're doing a redo anyway, make sure to overlap the flashing properly—gravity is your friend here. Learned that the hard way after a couple callbacks on my first jobs... nothing like redoing your own work to drive home a lesson, lol.
Totally agree about the sealant issue—seen that happen a lot, especially in climates with big temp swings. One thing I'd add is to watch out for galvanic corrosion too, especially if you're mixing aluminum flashing with different metals (like steel nails or screws). Had a job last year where the homeowner DIY'd repairs with steel fasteners, and it turned into a mess pretty quick...lesson learned there, lol.
- Had similar issues myself—galvanic corrosion's sneaky.
- Previous owner used steel screws on aluminum flashing around my chimney.
- Looked fine at first, but after a year or two, corrosion ate right through.
- Ended up redoing the whole thing properly with aluminum-compatible fasteners.
- Quick fixes rarely stay quick in my experience...
