Converting a Cargo Van For Mould and Chemical Avoidance

This post will cover converting a cargo van into a camper for mold avoidance (and for those with chemical sensitivities). I will focus only on a few key areas: insulating in a way that will not go mouldy - as metal walls are the trickiest thing to insulate because of the condensation factor. Most vans are built wrong and have mould (or will go mouldy). I will also look at MCS safe materials for the walls and interior, and a few appliances that are recommended. Building a camper that will be both mould-free and chemical-free is tricky!

Keep in mind a cargo van can be anything from a metal box with a bed to a fully decked out camper with a stove, fridge, sink, heater, AC, and even a full bathroom.

I recommend all of the products here, some products have affiliate programs and some do not. Upon purchase, I earn a small commission though affiliate links at no extra cost to you.

For assistance with converting a van with materials that are healthy for you and mould preventative, you can contact me here

If you are not sure if you can tolerate the system for mould preventative insulation I recommend getting in touch before buying a van.

converting a cargo van for mold avoidance MCS

Insulating a Cargo Van to Prevent Mould

The most important aspect of creating a mould-free camper is the insulation. Here is the key point: no water vapour can enter the wall cavity, in most conditions this means no air can enter or be behind the insulation. With exterior metal walls, as soon as you are heating the van to the point where the exterior wall will hit dewpoint, you have a serious risk of condensation and mould in the walls. So again, to keep it simple, no water so no air can enter the walls if you plan to heat your camper when it's cold. What folks are reporting is no air at all should be trapped behind insulation if you want to prevent mould.

Rigid Foam Insulation

Camp Like a Girl was not a book I was a fan of. Sara uses some XPS and some EPS insulation. XPS is a vapour barrier (meaning no water can pass through 1.5 inches), and EPS is not. So using XPS foam is one option to insulate your van. XPS or polyiso with foil backing are usually tolerable for most people with MCS.

However, just the foam on its own will not be airtight. You can use canned spray foam to fill in the gaps if that is tolerable for you - the full system that I have heard is working for folks, and was reviewed by a top building science expert, is to fill in the area behind the foam with spray foam and squish it in, leaving no air behind anything. It is not chemical-free but I have found it odourless once dry. Handi-Foam is the safest one, as it is GreenGuard Gold certified. Great Stuff will work for many people. This method involves a lot of canned spray foam. It also then needs to be riveted to the frame.

I would not recommend Sara's method of putting in EPS and not sealing it - this lead to condensation, but because she barely heated the van and had hot weather in the day this did work (at least for a while). Any foam with air behind can be a problem when heated. Breathable insulation is even more tricky. A few cold days in a row and this will start to be a problem.

A good way to go about it is - if it's warm enough - to sleep in the van empty and slowly work on insulating and building it out. The other option is to get it all done and then wait for it to offgas. 

Sara also uses insulation in the bed platform to keep the bed warm. I would be concerned here with flame retardants in the foam, and putting a bed on a flat surface is a no-no for mould. In the bed section I discuss how to use insulation under the mattress, or you need slats (unless it's an air mattress, or fully 100% encased in plastic). More on protecting beds from moisture and mould and keeping warm below. 

Spray Foam Insulation

Spray Foam is in theory your safest bet for preventing mould, as the foam will get into every crevice and form an airtight layer that will prevent all moisture from getting into the walls. 

using spray foam to insulate a cargo van
The best spray foams are Heatlock Soy line at Demilic and Icynene Proseal (both GreenGuard Gold) (closed cell). Both are polyurethane foams, from reputable companies that are usually easy to source. A reputable and very experienced installer is generally more important than the brand, as that is where the process goes wrong and can offgass majorly (Though do go with a well known brand). The DIY kits for this type of spray foam are a definite no. It must be closed cell, which is a vapour barrier. 

I recommend these to healthy people who are set on spray foam. I don't usually recommend them to people with MCS because I have heard bad stories (and there are better options for most homes). In theory, they do not offgas, but I hear many many stories from moderately sensitive people that this does offgas noticeably in buildings. A small sample may air out quickly, but test this in a building before using it. At least two years (if this is installed correctly) may need to be scheduled in to offgas this for the moderately sensitive. If not installed correctly it's a goner, you're going to be scraping out the whole thing. 

If you are mould sensitive but not chemically sensitive you could consider this in a van. I have heard though, both in Airstreams and in vans, stories of spray foam pushing out the frame in areas causing problems. A skilled installer may be able to clarify why this happens. But Airstream themselves as well as Winnebago have moved away from spray foam due to problems. 

Wall and Ceiling Materials 

how to build the walls and ceiling of a converted cargo van

Metal is your safest bet unless you are putting the plastic covers back on. For an extra layer of protection, caulk around the seams to prevent moisture from going into the walls if you do put the plastic covers back on. If you want your interior walls to be another vapour barrier layer, the metal or plastic should be used and caulked airtight. The drawback is another step to being able to check on your wall. If tin/aluminum tiles are used it's best that behind them is airtight (though if you have enough insulation this might not be necessary). If you don't have enough insulation to start with you could have condensation behind the wall cover. I have also seen gaskets with solid silicone sheets used to make something airtight (I don't know how well that worked but it's an idea to throw into the pot). 

In a cargo van or trailer, instead of using metal walls, my preference would be to keep the walls as simple as possible so that you can open them up to check on problems. You may want to use plastic sheets, or could simply cover the foam with the material of your choice. I like silicone leather as a wall choice. Though you could also tack up polyester fabrics, the grey side of housewrap (which looks cool), paint foil or metal walls with AFM metal paint, polyethylene wall tiles (if you can tolerate the glue), or seal everything with shellac and then paint directly over XPS.

There is no reason to use PVC, the most toxic plastic, in areas like the ceiling tiles. But real tin ceiling tiles could be used as a non-toxic alternative which add a fun look to your camper. 

While The Vanual looks very pretty with its wooden ceiling, I would avoid plywood as walls, ceiling or subflooring. There are just too many points where the wood hits the metal. If you are intent on getting this look, you would have to have lots of insulation at all the metal ribs to make sure dewpoint would never be hit. If that is possible, then you could use plywood with strips of wood over it to get the look in The Vanual. Use a wood that can take high humidity. 

Floor Materials

Marmoleum is a non-toxic floor for cargo van campers
Marmoleum Photo Green Design Center
I wouldn't use wood to raise the floor joists as the wood right against the metal could be a recipe for condensation and mould. Rigid foam may be your best bet for floors to solve the thermal bridging there, with the same system of canned spray foam above and riveting used to make it 100% air tight. 

Different flooring materials that could be considered include: leaving exposed metal, which could be painted with AFM Metal Primer with different designs for a pretty effect, or covered with rugs, or Marmoleum which is very tolerable (be careful here as Marmoleum has jute backing. Use plenty of insulation underneath and an underlayment with a thermal break to prevent condensation). 

Plastic sheets, rolls of silicone, other rubbers if tolerable, Silleather, EVA mats (this formamide free one).

Woven vinyl (that one is phthalate free), or hard vinyl plank like Armstrong brand (which is plastic through and through) or Cali Bamboo which has a limestone substrate should not be exposed to water/condensation. Both extremely low in offgassing, though still could be bothersome for some folks.

Plastic (polypropylene click together tiles), super duper easy to install. The brand is Europe is Bergo but in the US there are a number of them on Amazon like GarageTrac.

Your subfloor, if you are concerned about denting, would be plastic sheets or metal. MgO board has worked for some but is prone to cracking and is permeable.

You could use wood/engineered flooring or laminate if you are sure you have enough insulation underneath to prevent condensation from forming under the wood, a thermal break, and that the wood can withstand the humidity in your area. 

Interior Structures: Bed, Cabinets

preventing mold wood for ceiling and cabinets in a cargo van conversion
Photo Credit The Vanual
Sara and The Vanual used plywood for their bed bases. If it's softwood plywood it needs some time to offgas formaldehyde. The other option is Purebond plywood (I wouldn't use a non moisture resistant wood species in a van or small trailer -Purebond does come in different species but as far as I know the glue is not made to withstand high humidity). It also doesn't let the mattress breath. Mattresses are very susceptible to becoming damp in campers. Even in a house, one should never put a regular breathable bed on a solid surface. It would be best if the bed base was made of planks/slats that allowed some airflow. 

The bed should be flipped and checked often for dampness, especially if you cook or shower inside. Even better, in such a humid environment cover the mattress with a waterproof protector before installing it in the camper. This one is highly tolerable. The other option is to use a bed that doesn't transfer moisture and doesn't mould like this well tolerated TPU air mattress (takes only a couple days to offgas to my standards). But an air mattress won't keep you warm. I now use the thickest Thermarest which is more comfortable than an air mattress for me (took a week or so to offgas enough for me) - this still needs a waterproof cover or to be raised off a flat surface. I would use bedding made of polyesterwool, or silk, (and not cotton) because of high humidity in vans. 

How to keep warm in a bare metal van 

Since insulation is so tricky, many mold avoiders keep the van bare. The best way to stay warm is to have insulation below you and above you. Extra protection from the elements would be to add a canopy and heat sources:

I like the idea of adding insulation below you. There are a few ways. A thick Thermarest like the Mondo King does provide insulation. But I like the idea of adding a layer of insulation below that. I like Thermacork. You could use foam, EPS polystyrene (the kind made for packing or crafts should not have flame retardant), it is also a little bit breathable. You then add your waterproof layer to your bed if you have it over insulation. (No air mattress in this set up, it won't work). Then add a biomat or heating blanket. Above you you have your sleeping bag/blanket. Ideally for warmth, if you can tolerate it, your heating blanket is actually in the sleeping bag.

You can go one step further to stay warm and create a canopy or use a raised up tent inside the van. Anything to create a canopy - using the fabric of your choosing (as long as you have enough air) will keep this even warmer. If the area inside my tent or canopy is large enough for this to be safe - I add a tiny heater. I use this tiny Honeywell heater in all my small structures.


For cabinets, if you do use plywood, go for a formaldehyde-free plywood like Purebond (moisture resistant wood types only - the glues might not hold up to extreme humidity), offgas APA exterior plywood, or use solid wood (which may warp in high humidity). I much prefer metal cabinets. 

Ventilation in a Van

You need fans that move air out - one above the shower if you have one, and one in the general space. My CampLite had two fans and we still have problems just with cooking humidity making the mattress wet. The standard camper fans are called Fan-tastic.

Van Appliances

The Vanual has some cool tips for solar power, wiring and appliances. If you want to go off-grid you will need solar and you generally you will need to tolerate a fuel stove. The Vanual and other van owners speak highly of Goal Zero solar systems because of how easy it is to install. Some people just use the solar charger outdoors.

The other option is to wire the van to plug into a campground plug (or modify to plug into a house), this would allow you to cook on an electric hotplate and would allow an electric heater. Right now I use an Instant Pot to cook everything and I release the steam outside. This is a really good way to reduce moisture in a van or little trailer. You can cook almost anything in that. Using an electric blanket is a good heating option to save energy. The best kinds are the large ones with the 10 hour shut of time to keep you warm all night. If you don't tolerate those, a biomat may be better tolerated.

I would not use the stand alone propane heaters that go inside as they will not be safe for those with MCS.

For cooking, if you are off the grid you will need to burn some fuel to cook. Cooking outdoors is safer. Alcohol burning stoves are safer than propane. Though this won't be tolerable for many.

For a fridge I would go with a 3-way fridge that can run on propane solar or AC electricity. Unlike in most trailers propane is stored inside so this could become a problem. The Vanual recommends running this fridge on solar or the car battery.

Here is an example of a fully decked out custom van made for someone with MCS (you would want to see how the construction was done if you wanted to copy or buy this one).

Corinne Segura is a Building Biologist with 5 years of experience helping others create healthy homes.

For assistance with converting a van with materials that are healthy for you and mould preventative, you can contact me here

Carl Grimes, Certified Indoor Environmental Consultant, reviewed the mould preventative insulation system for vans. Extreme mold avoiders are using this system with success.

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charlie puth said...

Thanks for comment

Cort Johnson said...

Thanks for all the ideas. If you want to spend a ton of money on a product with questionable reliability go with Goal Zero. Otherwise put in your own battery, charge controller and solar. Definitely do not buy solar panels from Goal Zero - at 4 times the cost of other panels.

Thanks again for all the info though

Corinne said...

Hey Cort! Thanks for the feedback. Everyone I know building a cargo van camper is using Goal Zero! Any idea why?

Leslie said...

Hi, Corinne--I think that it's appealing to people who are unfamiliar with and intimidated by setting up a 12-volt system, because it's plug-and-go. While it is convenient (until it breaks), I agree with Cort that it's WAY overpriced. For the money one would save, one could hire a consultant to put together a nice little solar system. Also, I've had such bad experience with their customer service that I wouldn't buy any of their products again, personally.

Corinne said...

Thanks for the info on solar. Not my area of expertise!

Aviva said...

Hi Corinne, I'm so glad I found your website! This is great information. Do you think someone mold-sensitive can convert a used van into a safe living space, or does it have to be basically brand new?

Corinne Segura said...

A used van may or may not have mold problems and or leaks.

Anonymous said...

Would phenolformaldehyde plywood be okay to use if the formaldehyde value is only 0.018ppm? So it's much under CARB 2 which is 0.05ppm.


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