Recycled Polystyrene Insulation

Those living in extremely cold climates such as Canada and Alaska need lots of insulation so their home is warm and comfortable. We typically recommend using scoria, pumice, perlite and vermiculite, but from what we’ve been told these materials are not readily available or cost effective in the far north. Hideo, one of our readers, wrote and said recycled polystyrene is available by the container load, at least in their area. Here’s a possible solution for making rigid foam board insulation out of recycled polystyrene. (This hasn’t been done yet, but Hideo is planning to conduct experiments soon.)

The original idea came from Benefits of “Another little known solution is spraying Styrofoam with an organic citrus peel extract called limonene. This actually shrinks your pile of Styrofoam to about 1/20th of its original size! The resulting gooey substance can be used as super glue.” Limonene is available from companies such as Green

It seems you could make rigid foam panels with recycled Styrofoam using limonene. It melts Styrofoam into a glue that will bind itself together. Limonene is fairly expensive ($53/gallon or $175/ 5 gallons), so you’ll need to find a wholesale bulk price. Perhaps less expensive binders will be discovered in the future.

Details: Form the rigid foam panels in wood or metal molds about 2’x4’x10”. I suggest adding 1” layers of foam in the mold at a time. Mist the foam with a hand pump garden sprayer and then add another layer. Repeat. Apply moderate pressure from concrete blocks on top of plywood to settle the contents and create flat, uniform panels. (A layer of plastic prevents the plywood from sticking to the Styrofoam, workbench and form.) Experiment until the panels are rigid. At approximately R-4 per inch, the panels would be rated at about R-40. You could also make ceiling panels and insulated window shutters for nighttime use. Making the panels could be a profit generating home based business.

Floors: After testing the panels to be sure they don’t compress excessively, pour a concrete or geopolymer slab on top of the panels and install hydronic radiant floor heating (hot water flowing through PEX pipe) for maximum comfort. The floor will always be warm, and the air temperature will be uniform from the floor to the ceiling as hot air naturally rises. No ductwork and no blowing fans necessary. All you need is a small circulating pump and energy source (propane?).

People will soon realize that free polystyrene can be used as valuable insulation and then the price will jump, so I suggest lining up contracts with the best suppliers to take all their polystyrene for free. (Same thing happened with “waste” vegetable oil from restaurants. Companies who got in on the ground floor years ago cornered the market and probably made a fortune making biodiesel. Now it’s almost impossible to get.)

Foam shredding equipment (may not be necessary)

18 thoughts on “Recycled Polystyrene Insulation”

  1. thats a great idea! thanks SO your suggesting NO dirt in the bags at all and just styrofoam only? how do you feel about soil/styrofoam mixture? I already have some clay silt and gravel here on site. Would it just be more efficient to use only styrofoam?

  2. ok i am building an earthbag music studio in North Pole alaska. Furniture retail stores are great places to get FREE styrofoam the throw away loads of it. I am considering just breaking it down with my hands down to about half the size of my fist and just mixing it in my bags. Any thoughts? It might work well. Id like some educated input im very young and inexperienced

    • Build a post and beam structure that carries all of the loads and use bags of crushed styrofoam (smaller pieces the better) as ‘infill’ insulation. There are various ways to secure the bags. For instance, you could tie saplings between the poles and tie the bags to the saplings. Plaster everything.

      Wear a mask when crushing the styrofoam. Try various methods to see what’s fastest. Maybe chop it up with a knife?

  3. What about simply shredding the polystyrene foam (by rubbing it through 3/8″ hardware screen) and mixing it with wood sawdust to fill the tiny spaces between the foam particles- and just filling the mixture into plastic bags (even free used shopping bags)- inserting the bags between wall studs for new construction and also burried in the ground next to concrete foundation.

    I’ve never seen any safety rules against using flamable polystyrene board in walls.
    Are there safety rules against this flamable mixture in walls? If so, maybe there is a cheap flame retardant that must be mixed with it.

    Anyone want to comment?. If so, please email me also.


  4. Any idea where Hideo (Japanese name) is based? I’m in Japan and am hoping I’ll be able to buy some land and start something in a couple of years time, but don’t really know anyone doing earthbag houses here (actually, there are at least two people I know of who have both had work featured on this site that I have yet to contact…) and I have a few doubts about coping with the variable climate (hot, humid, wet, cool dry, cold/freezing… 5 seasons) and even more about planning permission in a place with a lot of seismic activity.

  5. Hi Owen, it’s me again! Lol. Just had an idea and want to know what you think? Could that superglue be sprayed on with a garden sprayer or some other device in layers as it dries?? I’ve never worked with it but think it may be easier and less time intensive??

    • A strawbale roundhouse on gravel bags sounds good. You might want to use gravel bags for the lower 2 feet or so. Scoria bags make a good insulated foundation.

      Please send drawings or pics when available.

    • We’re working on an earth-sheltered design for Canada and other extremely cold, windy areas. Bales are not recommended below grade. The plans will be published over the next 2-3 days in several blog posts.

      Bales are great above grade, but we wanted an earth-sheltered design for the harshest areas of the Far North.


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