I've actually tried something similar—used aluminum flashing to patch a tricky corner and then sealed the edges with silicone. Worked pretty well at first, but after a couple of seasons, the silicone started peeling away from the aluminum. Maybe it was because of temperature fluctuations or UV exposure...not sure.
"Silicone's more forgiving, but even roofing-grade stuff eventually breaks down under UV exposure."
Exactly my experience. Silicone's handy, but it doesn't last forever outdoors. I've since switched to polyurethane sealant for those types of repairs—seems to hold up better against weather and sunlight. Might be worth checking out if you're set on combining materials like that.
Honestly though, sometimes the simplest fixes are best. I've seen "temporary" aluminum patches last years without any fancy sealants at all, provided they're installed properly and angled right to shed water. Guess it depends on how much hassle you're willing to deal with later...
I've had mixed results with polyurethane myself. It definitely holds up better against UV, but I've noticed sometimes it seems overly stiff and can crack if the aluminum flexes too much with temperature changes. Maybe the brand matters?
Curious if anyone's tried butyl tape for aluminum flashing repairs... heard good things but haven't tested it personally yet.
I've used butyl tape a few times on aluminum flashing... it's pretty forgiving stuff, stays flexible, and handles temperature swings better than polyurethane in my experience. Just make sure the surface is clean—otherwise, adhesion can be iffy. Worth giving it a shot before redoing everything.
