Tried that flex seal tape on a leaking gutter joint and it actually made things worse

So my downspout had a crack near the elbow and I figured hey, $15 roll of that flex seal tape will fix it right up. I cleaned the area, dried it with a heat gun, and slapped that stuff on thick. Next rainstorm came and water was spraying out like a fountain from behind the tape. Turns out the tape trapped moisture against the metal and now I've got rust starting under there. I had to cut the whole section out and replace it with a PVC coupling and some ABS cement for like $8. Total wasted afternoon and now I'm out $15 for the tape I barely used. Anyone else had that tape just peel off or fail on outdoor stuff?

3 comments

3 Comments

cameron7241mo ago

My buddy tried that same tape on a hose bib outside. Stuck it on there, looked good for a day, then it just peeled right off when the sun came out. He said it was like the adhesive turned to dust.

sagey691mo ago

The sun really messes with that stuff (UV rays basically eat the adhesive alive). @cameron724 your buddy probably found that out the hard way like a lot of folks do. You see this all the time with cheap tape that isn't rated for outdoor use - the glue just bakes off and leaves a crusty residue instead. They should look for something that specifically says "UV resistant" on the label, not just the regular duct tape or packing tape that says it works outside.

parker_campbell9h ago

Read somewhere that some of those cheap tapes use a water based adhesive. Works fine indoors but the second it hits real heat or moisture it falls apart. Your buddy's story tracks with what I've seen. One guy on here said his tape literally melted into a sticky puddle after a hot afternoon. For outside stuff you gotta go with something like Gorilla or that 3M outdoor stuff. Even then check the fine print. Some brands still lie about being UV safe.