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

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This article is for general information only and describes my personal experience. It is not a blueprint, building plan, or safety guideline. The shelter approach shown does not meet building, electrical, mechanical, fire, or housing codes and may be illegal or unsafe in your location. Do not use space heaters or other heat sources inside foam structures. Use at your own risk and consult your local building official and qualified professionals (licensed electrician/contractor/engineer) before attempting anything shown here.

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

These shelters were super simple, quick to but up, super tolerable for me when I was chemically sensitive and it was 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 (using a space heater is surely against all safety guidelines, though).

This shelter can work in any climate, though it will not survive a hurricane!

It was highly tolerable for MCS and a good setup for mold avoidance.

The shelter was the last step in mold avoidance/homelessness for me before I moved back inside. I

moved back into regular housing for the first time in 8 years after this, and I continue to recover since then.

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 for me.

A wood frame like mine (pictured) is needed to protect the shelter from high winds and snow.

My frame was very robust, and survived a massive windstorm and a big snowfall.

I realised though that I didn’t necessarily require snow and wind protection, and I could have simply tied up a tarp over the raised-up foam shelter and skiped the frame altogether past snow season. 

Building the Simple Shelter

The shelter was made of a plywood platform and a wood frame, though I could have used metal or another material. 

We used some pressure-treated wood for the framing and some untreated wood.

Most of the points touching the ground were stumps, for added protection from rotting out (you can see that in the video).

The interior is an XPS foam box.

The box was made to fit the plywood, it was 4 x 6 feet but it could potentially be made in other sizes.

The height we decided on was 6 ft. 

We used the standard thickness of XPS.

For this to hold itself up without any supports (other than tape) as it’s designed, I used 2 inch foam.

What I could have done differently is paint the foam with ECOS primer and paint and possibly seal with shellac.

This should seal in flame retardants and the very minimal off-gassing.

Most extremely sensitive people do well with this foam; however, other potential foam types were polyiso or even Schulter boards. Schulter boards are the only foam board without flame retardants.

I made a model to test out ECOS paint and shellac and it worked really well (both the ECOS porch paint and the vinyl siding paint worked on XPS).

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.

I was heating, so I sealed up as much as I could on the inside with the tape that I tolerated. Green painter’s tape or Siga rissan tape are the most tolerated types. 

When taping the outside in heating season, I did not cover the seams fully, just enough to hold it together like in the videos (otherwise, condensation will form).

In cooling season, it’s the opposite (if I did put AC in there). 

Such a robust frame is not always necessary. I could have built the plywood platform, with the foam box on top, and simply strung a tarp over this if I didn’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.  

This shelter worked extremely well, though there are things to keep an eye on in the long term.

Here are some video tours which shows more, 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 at that time. 

I used two 100 ft extension cords (10 or 12 gauge) to power the heater and my laptop and light. (Running extension cords to power a heater in a foam shelter is against all safety guidelines and is not considered safe to do).

I needed one dedicated 10-12 gauge cord for 100 ft, for a 12.5 amp, 1500 watt heater.

It was plenty of heat for a small space!

I could not have anything else on that circuit in the house it was 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 off-gassing). 

I strung up this bulb (the string needed some off-gassing).

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 cargo trailer, on a different circuit. 

I used this little portable tub to “shower” in outside, and the luggable loo. 

More pictures of the framing: