I get what you’re saying about the temp, but honestly, I’ve never noticed humidity making much difference.
In my case, it’s always the can temp that changes things most. Maybe it’s just the brand I use, but even in a muggy crawlspace, it seemed to cure at the same rate as in my dry attic. Could be some foams are more sensitive than others?“my basement gets pretty damp and I swear the foam sets up faster down there.”
I’ve had the same thing happen—sometimes it feels like the foam just does whatever it wants regardless of how humid it is. I’m with you, can temp seems to be the big deal. I left one in my truck on a hot day and it basically exploded when I tried to use it... lesson learned. Out of curiosity, do you notice any difference between open-cell and closed-cell foams, or do they all act about the same for you?
Funny you mention the difference—I actually had better luck with closed-cell last winter when I was sealing around the new windows. It didn’t seem to soak up moisture the way open-cell did, and it stayed firmer, which helped with those weird gaps in my old framing. But then again, open-cell is way easier to trim if you overdo it. Have you ever tried using both types on the same project just to see how they hold up side by side? I’m always tempted but never quite get around to it...
Have you ever tried using both types on the same project just to see how they hold up side by side?
Actually did that when I redid the back porch windows last fall. Used closed-cell on the bottom where water sometimes sneaks in, and open-cell up top for the easier trimming. The closed-cell definitely kept its shape better, especially with those weird gaps you get in older framing. Only thing is, open-cell was way less hassle to cut flush—closed-cell turned into a bit of a wrestling match. If you’re dealing with tight spots, I’d lean open-cell, but for anything that might get damp, closed-cell’s worth the extra effort.
That lines up with my experience, actually. When I did the basement windows, I tried closed-cell in a couple spots where moisture’s a problem, and it really does stay solid, but trimming it was a pain—like trying to shave down a rubber eraser. Open-cell was way easier to work with, but I got nervous about moisture creeping in over time. Did you notice any difference in sound insulation between the two? I swear the open-cell seemed to muffle outside noise a little better, but maybe that’s just me.
Open-cell was way easier to work with, but I got nervous about moisture creeping in over time.
You’re right to be cautious about open-cell with moisture. I’ve seen a few jobs where folks used open-cell in basements and ended up with a musty smell after a year or two. As for sound, I’d agree—open-cell does tend to absorb noise better, probably just because it’s less dense. Did you do anything extra for vapor barriers, or just rely on the foam alone? Sometimes I’ll throw up a thin poly sheet if I’m worried.
- Totally with you on the open-cell being a breeze to install, but yeah, moisture’s the sneaky enemy.
- I’ve seen folks skip vapor barriers and regret it when that musty funk sets in—especially in older homes.
- Personally, I like to slap up a poly sheet if I’m even a little unsure. Cheap insurance, honestly.
- Sound-wise, open-cell is great, but if you want peace and dry walls, sometimes closed-cell’s worth the extra hassle (and cost).
- Funny enough, I once tried to “save time” and skipped the barrier... ended up dehumidifying my basement for a month. Never again.
Funny, I actually lean the other way on vapor barriers with open-cell in certain spots. If you’re in a climate where walls need to “breathe,” sometimes adding that poly sheet can cause more trouble—trapping moisture where you don’t want it. I’ve seen a few older homes where the barrier did more harm than good, especially with brick exteriors. It really depends on the wall assembly and local humidity swings. Not saying skip it every time, but sometimes less is more if you’ve got proper ventilation and drainage outside.
I get what you’re saying about vapor barriers causing more harm than good sometimes, but I’ve seen the opposite too—especially in the Midwest where we get wild humidity swings. My place is a 70s ranch with wood siding, and when I skipped a vapor barrier in one section (thinking I was letting it “breathe”), I ended up with some gnarly mold behind the drywall two years later. Not fun to discover when you’re just trying to hang a picture.
I guess it really comes down to how much moisture you’re dealing with and what your exterior is made of. With brick, yeah, maybe less is more, but with wood or vinyl, I’d rather have that extra layer of defense. Plus, if you’ve ever tried to explain “wall assembly” to an inspector who’s having a bad day… well, let’s just say I’d rather play it safe and deal with a little overkill than have to rip out drywall again.
But hey, every house is its own weird science experiment, right?
- Can totally relate to the Midwest humidity swings—seen a lot of window installs go sideways because moisture management got overlooked.
- Skipping the vapor barrier with wood siding is risky, especially if you get condensation or air leaks near the window frame. Mold loves those hidden corners.
- Window replacement is one of those spots where the details matter: flashing tape, caulk, and yes, a well-placed vapor barrier (or at least a smart air barrier) can save a ton of headaches later.
- I’ve had inspectors nitpick about “overkill” too, but honestly, I’d rather deal with a little extra tape or membrane than demo a soggy wall down the line.
- On brick exteriors, I sometimes hold back—brick handles moisture differently, so you don’t always want to trap it. But with wood or vinyl, that extra layer buys peace of mind.
- Every house is its own puzzle, for sure. I usually tell folks: check your local code, think about your climate, and don’t skimp on sealing up around the new windows. A little paranoia goes a long way...