Warning: That insulation R-value chart for containers is way off

I was planning out a container home build for a side lot here in Denver and kept seeing these R-value charts online saying a single container wall with spray foam hits like R-20 easy. Then I actually called a local insulation supplier who works on these things, and he told me the steel frame itself creates thermal bridging that drops real performance to more like R-10 or worse. He pulled up some testing data from a project they did last spring on a two-container setup in Golden, and the numbers were way lower than what the DIY blogs claim. Made me realize I gotta plan for double the insulation thickness or add an exterior wrap if I want to keep heating costs down in winter. Has anyone else run into this cold floor issue after a real winter season in theirs?

2 comments

2 Comments

ninam8616d ago

Hang on, I gotta push back on this a little. I’ve been living in a single container in Boulder for two winters now and my R-value came out fine with just standard closed cell foam about 3 inches thick. My heating bill was like $40 last January and I didn’t have any cold floors. Maybe those guys in Golden had a different steel gauge or they didn’t seal the seams right because thermal bridging is real but it’s not automatically a deal breaker if you do a decent job with the install. I’ve seen those same charts and yeah they’re optimistic for a full wall but calling it R-10 sounds like an extreme case or they used a bad spray foam brand. It could depend on how your container is oriented too, mine faces south so the sun helps a ton in winter.

joseph_lewis9216d ago

Yeah I remember talking to a guy in Denver who insulated his container with wool blankets and a space heater and he swore it worked fine but then he moved to Flagstaff and it was a whole different story. @ninam86 has a point about the orientation thing though, my buddy's container faces north and he regrets it every winter.