Building with disposable white foam coolers?

Hello, and thanks for the many good postings on this site. My workplace generates a steady stream of white foam coolers and freezer blocks used for shipping medications and vaccines. We try to give the coolers and blocks away, but they often go into the dumpster. The coolers are about 14"x11" and 10" tall without the lid. Corners are rounded, and the walls are about 2.5" thick. Liquids will eventually leach out if allowed to stay in the coolers. Has anyone tried using these like Faswall blocks, perhaps packed with sand and covered with lathe/mortar, cob, etc.? I'm thinking they would work better if the lids were left off. XPS and EPS are used under footing walls, but would the cooler foam have sufficient bearing strength to serve as a footing wall? They are a good length for the 12" cordwood log ends we have, and we wouldn't need to further insulate the foam footings. Thanks for any input, as there doesn't seem to be much information about this on the web.

I work a lot with polytyrene beehives. They are made with a super-dense and water proof form of polystrene. I would be very dubious about using those in any form of construction. They are easily damaged by impacts, can shatter if dropped awkwardly, get eaten by rodents etc...

The lightweight poly you describe would have all those problems and more. It would need to be clad in something impact resistant, handled carefully through the building process, kept dry, and kept totally isolated from rodents etc... And underload I would expect  them to compress by a reasonable percentage over time, causing settling issues.

I could see them having some value if used as an insulation... but again, they are highly flammable so maybe not.

In my opinion they are useless for anything else than reusing as a cooler and then ending in efficient incinerator.

1. Why would someone want to use plastic in their home? All new materials are always safe until 50 years pass and the recent discovery says they are not - look at asbestos, microplastics, hormone mimicking plastics, etc. On top of that plastic always looks trashy, because it is not compatible with natural materials surrounding it, does not decompose is some graceful way. Compare a mobile home/RV to some old stone/cob/wood hut, even dilapidating.

2. Even if they were ok then it would still make no sense - mice really like to live in styrofoam filled walls, followed by other vermin. Of course someone could say that "if properly built then..." -it's an argument used for stick built homes. Penetrable cavity will be always penetrable cavity and eventually it will fail. I have never seen a house with cavity walls that would not have something living in them. It also crumbles when handled and litters the surrounding areas.

3. It's really flammable.

4. Even if 1, 2 and 3 could be disregarded, then attaching anything to fragile plastic would be a challenge eventually creating unreliable system. It makes sense to create costly/labor intensive solutions but for quality materials - custom stonework, stainless pipes, etc.

There do exists ICF system - styrofoam/insulative forms to be filled with concrete. It's not good either: you need insulation always on the outside of thermal mass, inside of the house you have more flammable plastic and you have to cover it with some boards - more cavities and labor.

Someone said on this forum, regarding earthships - why to drag toxic tires to your property if you already have dirt, gravel, water and maybe clay?
Good architecture is made of good materials, is beautiful and functional. Disposable foam coolers do not fall in any of these categories.
Building a home is SO MUCH work that it makes sense only to use good materials at minimum. Also any subcontracted labor is so expensive that it only the best should be used in such a case.

The best way to use styrofoam is to feed mealworms:

https://permies.com/t/50485/composting/Mealworms-Eating-Styrofoam

I saw this and had to check: did I post this?

Seriously, this has been in my mind for years, I just never have had enough available at one time to make it feasible.
I am infilling the pallet walls of my greenhouse with chunks of these coolers surrounded by dry earth.

If I were going to use them as building blocks, I think I would use rebar pins in a perimeter foundation and impale the coolers on them.
To fill their voids maybe use the lids and other bits of the coolers, cut to size.
You could even put two of them together this way.

I think treating the coolers with borox could reduce flammability significantly.
It might even dissuade pests.
The problems of flammability and pests are faced  by strawbale builders, so we should borrow their solutions.


A ferrocement or Latex Concrete  skin might be enough to make them load bearing.
Earthen plaster over metal or plastic mesh would be enough to act as a non-load bearing structure.

You could also use the coolers as raw material for styroconcrete or styroadobe.

I appreciate the effort to try to reuse something that is otherwise trash, however… I built my own faswall home and I do not think that styrofoam coolers and faswall blocks are in the same category.

Thanks to all for your feedback. While it would seem great to use these coolers for something meaningful and permanent like a building foundation, it does make me nervous to think about tons of cordwood masonry resting on the foam and/or its filling. Even if the bottoms were cut off, making the coolers into a form for a filling with predictable compressive strength, there are still other concerns. The coolers are not Faswall and were not designed to be used in construction. It might make more sense to use them as infill, but there would still be the issue of properly protecting them from the elements, rodents, etc. And even then, would the coolers eventually become toxic or shorten the lifespan of the building? I like the thought of feeding the coolers to mealworms and then feeding the mealworms to trout or chickens, but it looks like current research isn't conclusive about potential toxicity. For now I will look the other way as I walk past the pile of unwanted coolers, which are sooner or later bound for a dumpster, a creek, or maybe even some other person's building project.

I think they may make
- great dust proof storage boxes for items that fit and are not used often.
- good blocks to build outbuildings and covered with netting and ferro cement to keep them intact from anything.
- grow boxes for small balconies.
- storage box for pipe fittings
- or pipe clamps used in fencing
- formwork under concrete slabs with reo.