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Community and Q&A

How to insulate a shipping container home?

SirKoda | Posted in Energy Efficiency and Durability on

I would like to understand how to best insulate a shipping container home. i am thinking of building on a pier system.

Specifically I am wondering about the double sided foil such as Radiant guard that comes in both permeable and vapor barrier. Which do I put on the inside and which goes on the outside. I live in the Seattle area Marine Zone 4-5.

What insulation do I use in combination with this radiant barrier on the inside or the outside. I want to add outside cladding to my container such as Cedar siding and will add a roof deck which will have drainage under it away from the roof therefore I am thinking I will be able to add insulation on top of the outside.

Should I use spray foam on the underside?

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  1. Malcolm Taylor | | #1

    I'd dissuade you from using shipping containers as a starting point for a home.

  2. User avatar GBA Editor
    Martin Holladay | | #2

    To insulate any roof assembly, wall assembly, or floor assembly, start with insulation, not a radiant barrier. Here's a link to an article with more information: Radiant Barriers: A Solution in Search of a Problem.

    Steel shipping containers have low ceilings. To avoid thermal bridging through the steel (which happens if some of the insulation is interior and some of the insulation is exterior), as well as to avoid the low ceiling problem, all of your insulation should be on the exterior side of the shipping container. You end up building a house around the shipping container, which is expensive. My advice: Just build the house (without the shipping container).

    -- Martin Holladay

  3. Charlie Sullivan | | #3

    My new favorite way to explain the irrational attraction to shipping containers is by analogy to the story of stone soup. If you haven't heard that story, it's about a hungry traveler who tells villagers that he can show them how to make soup from a stone. He gets them to boil water for him and he puts a (clean) stone it. He pretends it is becoming good soup, but suggests it would be even better if they added a little seasoning. Then maybe a few vegetables, and some beans, and so on until they have provided all the ingredients of a good soup. They are impressed at what a delicious soup he has made from a stone.

    The shipping container is just like that--a way to claim that you have made a house from waste materials, when in fact, you still need to do all the expensive things. And unlike stone soup, the shipping container constrains the design excessively, and costs real money.

  4. Erich Riesenberg | | #4

    What is frustrating to me is that for a large subset of people who pay any attention at all to energy efficiency, things like shipping container homes occupy a substantial amount of day to day time and thought.

    So many resources spent trying to make a bad idea seem reasonable, instead of talking about the very basics of say buying a fixer upper and tearing it down and putting it back together properly. Which could be a good idea in every city in America.

  5. User avatar
    Jon R | | #5

    I have one and agree with the above statements. Maybe they make sense if you value the security and air tightness. Or you can simplify some building permit issues. "High Cube" versions are preferred.

    My plan - glue EPS foam to the exterior, add corrugated steel roofing on top and stucco (maybe synthetic) on the sides. No radiant barrier (other than painting everything white).

  6. User avatar
    Dana Dorsett | | #6

    To meet IRC code on a U-factor basis (the only approach that makes any sense at all for a steel structure) would need a continuous R28 or so under the bottom of the thing, and R35 on the top, and R15 on the walls.

    You won't get anywhere NEAR that kind of performance out of any type of radiant barrier product without a complicated set of layering with trapped air spaces. It's useless for this application in general, and even more so in your climate.

    If you can find a local source of reclaimed rigid foam, 5" of 2lb roofing polyiso on the bottom, 3" on the walls, and 6-7" on the top would work, and it would be cheaper & greener than spray foam solutions.

    In Seattle's 10 month heating season climate, using high solar reflectance finishes on the exterior would be moving in the wrong direction, lowering the average surface temperature, increasing energy use.

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