Foam insulation deteriorization
I installed some new trim around some fixed windows about 15 years ago. I used a spray, expansive foam insulation (the poly type, not latex) to fill the gaps. I thought this was the best way to handle this. I sprayed it into the gaps and everything had hardened by the time I installed the trim over it.
Yesterday I removed the trim to install new replacement windows. I was very surprised to see that all of the spray foam had deteriorated/melted away (see the picture). The fiberglass was still intact.
At the time I installed this, I was shopping at a local place called Home Base (now out of business), but I don’t recall the brand of the foam. It came in an aerosol can.
Lately I have been using Great Stuff from HD. I would like to use the Great Stuff on my new window install, but now I am worried the foam will deriorate after I seal it up and can’t see it anymore.
Has anyone else experienced this kind of problem? Any recommendations? Maybe I just got a bad batch of foam. This is a south wall in southern Colorado, so it does get very hot.
Replies
Hi bergsteiger1,
I was very surprised to see that all of the spray foam had deteriorated/melted away (see the picture).
Wow the only time I've ever experienced anything close to that with "Great Stuff" was when I put it on the outside of an old shop that took years to complete. It was south facing so it got plenty of sun and was completely unprotected....it got crumbly but never completly came apart...I think it was about 10 years before I ever got around to covering it with trim.
Pedro the Mule - Got it on my fur a few times too....seems to never go away then
I think I see where you have FG insulation around the window and you said that you also sprayed foam in the same cavity. If you disturb the foam while it is curing it will not cure. Just wondering if you filled the cavity and as the foam tried to cure the FG expanded.
berg
I have seeen foam do that when it is applied in extremely cold conditions.
my 2 cents.
Rich
That doesn't look to me like it was installed right to begin with. Either not enough of it to expand and seal, or disturbed and shrunk back as wit5h cold or other activity while curing.
Colour does suggest polyurethene type tho. My first thought before seeing that was that it could have been one of the many other imitations.
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In my previous life I have worked as a materials engineer (fancy name for someone with a chemistry degree who doesn't play in the lab). Some of my jobs have involved urethanes, including foams.
Under certain circumstances, urethanes can "revert", which means that they become liquid. The navy found this out when they used early foams to package certain products; when they opened them they had to spend hours cleaning off the sticky mess. I had the same problem with a foam "shock" absorber for my turntable. It turned sticky, and I had to spend hours cleaning some of my valuable vinyl.
The reversion is caused by moisture. Especially at high concentrations it will attack certain types of urethanes. High temperatures don't help either. In the case of my turntable, simply long exposure at room temperatures will do the job.
In your case I think you had two problems:
Thanks to all for your comments. I guess I will still use Great Stuff since if it works as designed it should be better than FG. Maybe what I used before was a cheap brand. And the idea that moisture getting in there is a possibility too. I'll be sure to use waterproofing membrane around the window outside so that should not be a problem. And I will be sure to wait to be sure it is fully cure before covering it with the interior trim. Thanks again guys.
just saw this with a thread I have going on best caulk, lexel was recommended.
Where not to use Lexel
Lexel should not be used in areas of continuous submersion (i.e., aquariums or swimming pools). Do not use Lexel in areas where temperatures exceed 200ºF. Lexel may damage some plastics, such as polystyrene foam insulation. Plastics not listed should be tested for Lexel compatibility before general application.
If you caulked, maybe your caulk was the problem?
No, I just used foam.But as it turns out, the instructions that came with my new Milgard windows say to not use any type of expanding foam around them. I have other Milgard windows installed by pros but they are all foamed and I have not had any problems. I think I'll call Milgard and ask them to explain. I would have thought the minimally-expanding foam designed for windows would work fine without bending the frames.
A minimally expanding used carefully is fine.So many DIY and hacks have overdone the foam thing with regular foam that window makers had a lot of service calls/complaints, so they have over reacted to some degree, some naming only a specific brand of foam and others saying no foam at all.
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Thank you