I've definitely noticed altitude affecting foam expansion too, especially when I first moved up here. I'm around 7,200 ft, and the first time I tried sealing windows, the foam just didn't expand like it did at lower elevations. Thought it was a bad batch at first, but after some digging around online, turns out altitude really does play a role—something about lower atmospheric pressure affecting the gas bubbles in the foam.
Temperature swings probably factor in as well, though. We get pretty drastic shifts here—warm sunny afternoons followed by freezing nights—and I've noticed that even properly expanded foam can sometimes pull away slightly from the frame over time. So maybe it's a combo of both altitude and temp fluctuations?
Either way, I've found that using foam specifically rated for high-altitude or colder climates helps a lot. Costs a bit more, but worth it to avoid redoing the job later...
Interesting point about altitude-rated foam, hadn't thought of that before. But could it also be the framing material itself causing some of that pulling away? I've noticed wood frames tend to expand and contract quite a bit with temp swings, maybe even more than the foam. Wonder if using a flexible sealant or caulk alongside the foam might help keep things sealed better long-term... Has anyone tried combining materials like that?
"Wonder if using a flexible sealant or caulk alongside the foam might help keep things sealed better long-term..."
I've done exactly that—foam first, then a flexible caulk bead around the edges. Seems to hold up better through winter. Curious though, anyone notice differences between silicone vs polyurethane caulks?
I've tried both silicone and polyurethane, honestly didn't notice much difference long-term. Silicone seemed easier to apply neatly, but polyurethane felt tougher once cured. Still skeptical either beats good old-fashioned weatherstripping tape though...
I've messed around with silicone and polyurethane quite a bit myself, and honestly, I lean toward polyurethane for windows exposed to harsher conditions. A few winters back, I sealed up some drafty basement windows with silicone, thinking it'd be easier and quicker. It was neat and tidy at first, but after a couple of seasons of freezing and thawing, it started peeling away in spots. Ended up redoing the whole thing with polyurethane, and it's held up way better since then—no peeling or cracking yet.
That said, I totally get your point about weatherstripping tape. For quick fixes or temporary setups, it's hard to beat. But if you're dealing with serious cold and altitude, polyurethane seems to handle the stress better long-term. Just make sure you prep the surface properly—clean thoroughly, remove old residue, and let it dry completely before applying. Makes a huge difference in durability.
Totally agree about polyurethane holding up better in harsh conditions. Silicone's fine indoors or for quick fixes, but outdoors it just doesn't flex enough with temperature swings. One thing I'd add—make sure you're using a quality caulk gun. I learned the hard way that cheap ones can make applying polyurethane a nightmare... uneven beads, hand cramps, you name it. Upgrading to a decent dripless gun made the job way smoother and cleaner.
"I learned the hard way that cheap ones can make applying polyurethane a nightmare... uneven beads, hand cramps, you name it."
Haha, been there, done that. Nothing like trying to squeeze out a smooth bead with one of those bargain-bin caulk guns and ending up with something that looks like abstract art. Totally agree on upgrading to a dripless gun—makes a world of difference. Polyurethane is definitely the way to go outdoors; silicone just doesn't cut it when temps swing from freezing nights to sunny afternoons. Learned this myself after redoing my cabin windows twice in one year (yeah, stubbornness runs deep here). Good call on mentioning the quality gun though, it's one of those things you don't realize matters until you're halfway through a messy job and your hand feels like it's about to fall off.
I've actually had decent luck with silicone outdoors, even in some crazy temp swings. Maybe it's less about the product and more about prep? I admit though, my beads still look pretty abstract... probably user error more than anything, lol.
"Maybe it's less about the product and more about prep?"
Definitely agree on this point. When I first tackled my windows, I spent hours researching sealants and ended up going with silicone too. The key, I found, was making sure the surfaces were spotless and bone-dry before applying. My beads still aren't winning any beauty contests either—abstract art is a generous description—but they've held up surprisingly well through some brutal winters. Maybe practice makes perfect...or at least slightly less abstract?
"abstract art is a generous description"
Haha, relatable. But I'm curious—did you notice any difference in durability between thicker and thinner silicone beads? I found thinner beads neater, but they seemed to crack sooner in extreme cold...maybe just my luck?