Is everyone forgetting about insulation for container homes?

I've been looking at container home builds online for a few years now, and I keep seeing people post these amazing photos of their exteriors and interior paint jobs. But then they get to the insulation part and they just throw in some spray foam without thinking about condensation. I worked on a buddy's container cabin up near Asheville last summer, and we spent a whole weekend just figuring out the vapor barrier because if you get that wrong, the metal will sweat and rust from the inside out. I've seen two builds already where the owners posted about mold issues 6 months later because they skipped the closed-cell foam and used fiberglass batts instead. It's not glamorous work, but if you don't plan for air movement between the container walls and the insulation, you're basically building a damp locker. Has anyone else run into this problem after their build was supposedly finished?

2 comments

2 Comments

the_eric2h ago

The closed cell foam vs. fiberglass debate is the big one, but what about people who use those rigid foam boards instead? I've seen a few builds where they glued those directly to the metal and left zero air gap, thinking it would stop condensation. Six months later the foam was wet on the backside and the container walls had surface rust starting. Did your buddy's cabin use any kind of furring strips to create that air channel, or did you seal it up tight and just trust the vapor barrier?

max38824m ago

Yeah one of the old-timers on a container forum I used to lurk on tried that rigid foam trick. He glued the boards straight to the metal like you said, no gap, figured the foam's closed cells would keep moisture out. Nope. Six months later he pulled a panel off and there was condensation running down the inside of the steel. The foam was soaked on the back side too. He ended up ripping it all out and doing furring strips with a small air space. My buddy's cabin used those strips - no way around it from what I've seen.