Why I finally stopped doubting duct seal after my basement rim joists hit -35 C last winter

I figured the guys saying a $4 bucket of putty could seal gaps better than spray foam were just cheaping out, but after checking my basement temps this January the stuff actually held steady where everything else had pulled away from the concrete.

2 comments

2 Comments

emeryfox1mo ago

Minnesota here, and I had that exact moment of clarity about duct seal a couple years ago when my foam kept popping out in big chunks. It's funny how the simplest stuff often works best, like how my grandpa's old cast iron skillet is still better than any nonstick pan I've ever bought. We get so sold on fancy solutions (you know, the stuff with the big marketing budgets) that we forget basic physics and chemistry do the real work. Same thing with using plain vinegar for cleaning or a simple wool blanket instead of some high-tech fabric. The duct seal just sits there doing its job without drama while everything else fails around it, which is basically my whole philosophy on tools now.

the_dakota1mo ago

Duct seal is one of those things that looks too simple to work until you actually need it to work. I had the same experience last winter when my spray foam shrank and left gaps you could see daylight through, but the duct seal I slapped in as a temp fix never budged. That stuff just bonds and stays flexible no matter what the thermometer says, and I won't use anything else for rim joists anymore.