Suggestions for high performance container home wall assembly
BenFoster02
| Posted in Green Building Techniques on
Hey everyone,
I have experience with wood and steel stud wall assemblies. Including high performance passive house wall assemblies. However, I was wondering if anyone had any ideas to make a container home walls high performance. Not any information online about it and was wondering if someone could help me put together a high-performance wall assembly for a container home.
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This foam product is made for the situation: https://www.insofast.com/promos/insulation-panels-for-shipping-containers.html. You can search this site for many similar discussions: https://www.google.com/search?q=greenbuildingadvisor.com%3A+shipping+containers&rlz=1C1ONGR_enUS1048US1050&oq=greenbuildingadvisor.com%3A+shipping+containers&aqs. (The in-site search function doesn't work as well as Google.)
Generally speaking, most of us on GBA agree that containers are not a good way to build any house, much less a "high-performance" one. You have to use foam, and the containers are not as structurally sound as people think--by the time you've made your openings and reinforcements, in most cases you'd be better off just framing something similar from wood.
Re insofast. I would think this would be a questionable assembly in cold climate. The metal container skin is a true vapor barrier and in this case it is on the outside. Any moisture that makes it behind the rigid has nowhere to go, it will condense when it hits the cold metal and mold over time. Could be argued that the foam layer can be made air tight but it still looks like a risky assembly to me.
I think for shippling containers used for living space with typical house humidity levels, your two robust options are spray foam on the inside or exterior insulation.
For the OP. the best way to make an energy efficient container house is by not using a container. Instead use corrugated metal skins (same stuff the container sides are made out of) as cladding over a standard house build for the look.
I generally agree, but I have never made it far enough with people who want to convert containers into homes to look into it more deeply. If I were forced to do one, I would be inclined to spray-foam the exterior so I didn't lose too much interior space, but then you need to cover the exterior with something--likely metal panels as you suggest for wood-framed buildings.
I assume you mean shipping container?
Here's the problem: the shell is highly conductive, which means it has to be insulated on the interior. The shell is vapor closed, which means your assembly has to dry to the interior and be ventilated and conditioned to remove moisture. And the container just isn't that big -- typically 8' wide, but the sides are inset so you have a little over 7' usable before insulation. With a decent level of insulation you're lucky to end up with 6' of usable space. Which makes for a tricky area.
I think shipping container projects work when you acknowledge you are doing it entirely for the aesthetic, and will subordinate other concerns to achieve the look. Part of that means forgoing the goal of having a high performance envelope.
This is a well thought out critique of the difficulties: https://www.youtube.com/watch?v=i7yEDz6bCfU
Agree with everyone’s general feelings about building with shipping containers. Speaking from experience. Not sure if I’d call it high performance, but we bought a stud welder and used it to affix vertical wood strapping to the exterior with 3 x 1/4” threaded studs. Sandwiched 4” of rigid foam in 4x8 sheets to the exterior with 3/4” horizontal external strapping. Metal and wood siding will finish the wall. Still haven’t figured out how to do the doors, likely something internal like the product linked above. I have nightmares about the finishing details.