Simple Insulated Shelter for Chemical Sensitivity (MCS) and Mold Avoidance

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This post is about two highly insulated shelters I made with rigid foam, raised off the ground and covered in a tarp. 

These shelters are super simple, super tolerable for the chemically sensitive and are ideal for mold avoidance in cold weather (or even in hot weather).

This has the same insulative value that a house would have. I was very warm inside in Canadian winters with one space heater. This shelter can work in any climate, though it will not survive a hurricane! It was highly tolerable for MCS and a good set up for mold avoidance.

These shelters were an incredibly important step in me healing enough to live inside. The shelter was the last step in mold avoidance before I moved back inside. I moved back into regular housing for the first time in 8 years, and I continue to recover.

This is something I wish I had known about much earlier on, as tent living and custom trailers/vans are difficult to make and to live in, especially in cold weather. It’s hard to keep a steady temperature, it’s difficult to insulate trailers and vans, and it’s hard to keep them from going moldy. This shelter solved all those problems.

A wood frame like mine (pictured) is needed to protect the shelter from high winds and snow. My frame was very robust, survived a massive wind storm and big snowfall. If you don’t require snow and wind protection, simply tie up a tarp over the raised up foam shelter and skip the frame altogether. 

Building the Simple Shelter

The shelter is made of a plywood platform and a wood frame, though you could use metal or another material. We used some pressure treated wood for the framing and some non-treated wood.

Most of the points touching the ground are stumps, for added protection from rotting out (you can see that in the vide

The interior is an XPS foam box. The box was made to fit the plywood, it was 4 x 6 feet but you can make this any size you choose. The height we decided on was 6 ft. 

You can use any thickness of XPS that you want. Though for this to hold itself up without any supports (other than tape) as it’s designed, I would use 2 inches.

What I would do differently next time is paint the foam with ECOs primer and paint and possibly seal with shellac. This will seal in flame retardants and the very minimal off-gassing. Most extremely sensitive people do well with this foam.

I made a model to test out ECOS paint and shellac and it worked really well (both the porch paint and the vinyl siding paint worked). With or without Zinsser Bullseye Shellac.

I would also use clear tape next time because it would look better!

I would buy a tarp that covered the wood but still had air movement underneath.

When you are heating you should seal up as much as you can on the inside with the tape that you tolerate. Green painters tape or Siga tape are the most tolerated types. 

When taping the outside in heating season do not cover the seams fully, just enough to hold it together like in the videos.

In cooling season it’s the opposite (if you did put AC in there). 
Such a robust frame is not always necessary. You can build the plywood platform, with foam box on top and simply string a tarp over this if you don’t have strong winds or a lot of snow.

A number of details are necessary to control condensation on the inside of the tarp in heating season, as condensation can drip down onto the wood or foam. We used spacers on the sides, a criss-cross on the top, and a piece of plastic suspended above the roof of the foam shelter to stop water from dripping down and wood from getting wet and moldy. 

Please contact me for details if you want help setting something like this up.  

This shelter worked extremely well though there are things to keep an eye on in the long term. Here are some video tours which will help you to picture how it works, shows the spacers, and other details like windows and power. 

The whole thing was completed with some volunteer labor and some paid labor for 1000 CAD.  I used two 100 ft extension cords (10 or 12 gauge) to power this heater and my laptop and light. You need one dedicated 10-12 gauge cord if it’s 100 ft, for a 12.5 amp, 1500 watt heater. Plenty of heat for a small space! You can’t have anything else on that circuit in the house it’s running from or inside on that cord).

I used this plugin thermostat to control the temperature and keep it very even (which needed a surprising amount of offgassing). I strung up this bulb (the string needed some offgassing).

I used the Mondo King Thermarest and I covered it in two Husky bags (taped together) to keep it dry. A small fridge was kept outside in my trailer, on a different circuit. 

I used this little portable tub to “shower” in outside, and the luggable loo. More pictures of the framing: