Non-Toxic Grout and Thin-Set Mortar

Updated summer 2019

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Non-Toxic Thin-Set Mortar

Non toxic underlayment with chemical free grout
DITRA over the first layer of thin-set
I used Custom Building Products Thin-Set Mortar which is zero-VOC (and mildewcide-free). It had a bit of a smell when wet but seemed fine once dry. You want a water-based thin-set that is not mixed with latex or acrylic additives. The unmodified one is recommended for floors and may not be suitable for all applications. Schulter also makes an unmodified thin-set mortar.

These non-toxic thin-sets are more prone to cracking than ones with more additives, and you have to check if you application requires polymers. Thin-set mortar is also known as dry set and drybond. 

Avoid the toxic epoxy thin sets. Avoid toxic mastics as well. Although there are some safe and tolerable tile glues like AFM 3 in 1.

Non-Toxic Tile Membranes / Underlayments

non toxic no offgassing odourless underlayment
Schluter Kerdi 
Over the first layer of thin-set I used Schluter DITRA (polyethylene with a fleece backing), an uncoupling membrane that will help prevent cracking when my tiny house moves (it worked well and did not have a odour to me). Polyethelene is a very safe plastic.

If you just need a waterproofing membrane use Schluter Kerdi (a modified polyethylene (PEVA) core with non-woven polypropylene).

For a tiled shower, the Kerdi shower system is recommended by architects to create a mould preventative shower. Be sure to test all parts including Kerdi Fix sealant if you are sensitive to chemicals (though you can use your own thin-set, as long as it's compatible).

Instead of using the membranes over backer boards, you could use Kerdi boards or Wedi panels. Test for tolerability before proceeding, they are not odour-free. These simplify things by replacing concrete backer boards and membranes with one layer that is does not contain mould food. The panels are non-toxic 0-VOC polystyrene with a membrane already integrated.

Concrete Based Non-Toxic Grout

non toxic tiles with non toxic grout and grout sealer
My completed tiled bathroom!
I used this Custom Building Products grout, the same brand as the thin-set, which is also 0-VOC and contains no mildewcides or antimicrobials. It comes in sanded and unsanded and in different colours. (Unsanded is for marble and certain tiles). It barely had a odour, though it does have polymers which may not be tolerable to some.

If that one is not tolerable, Hydroment is also recommended for people with sensitivities. However, it has a small amount of latex additives and contains mildewcide.

If you need to avoid all additives, you can make your own with Portland Cement (no additives) mixed with sand, lime and water for a totally chemical-free grout. Here are the ratios from Craftsman's Construction Encyclopedia. To mix your own chemical-free grout it is a ratio of portland cement to sand, 1:1 for 1/8th joints, 1:2 for 1/2 inch joints, and 1:3 for over 1/2 inch joints. Adding up to 1/5 lime increases workability.

Laticrete also makes a number of 0-VOC grouts and thin-sets that may work for you. It's a matter of finding out which additives work for you and if additives are required for your application. Before planning out the project (especially shower walls, make sure you know which kind of grout and mortar are required and if they work for your health concerns).

What are Grout Additives and are They Toxic?

Those who are sensitive will probably want a concrete-based grout (like those above) and then see which if any additives can be tolerated. Since additives are trade secrets and polymer is a word that can mean a variety of chemicals (there are over 10,000 polymers that can be used in cement) you will probably have to test them. Common polymers in grout include: latex-based, Acrylate copolymers (acrylic eg. PVA), Styrene Butadiene Rubber copolymers (SBR), and Vinyl Acetate-Ethylene copolymers (VAE), and Ethylene-vinyl acetate (EVA).

They might come mixed in or you might mix them in yourself. Mixing them in yourself has the advantage of being able to test the additive against your sensitivities in a more concentrated form, on the other hand, you may not want to test the grout until it has cured. Polymers are added to improve chemical resistance, reduce porosity, improve flexibility, and freeze/thaw stability (source).

You will have to find out when and where you need additives, which depends on your project.

Are Thin-Set and Grout Safe - Why do They Have the Prop 65 Warning?

is thin set, grout safe? why is there a prop 65 warning Sanded grout and thin-sets contains silica (the same substance as glass) which is harmful to breathe in when in dust form; you will see a Prop 65 Warning on every product that contains silica dust. Use a N95 mask (or better) when mixing it until it is fully wet. This is completely safe when it is no longer in dust form. There may be other minerals in there that are a problem in dust form like aluminum oxide, which can result in a high health rating on the SDS and other warnings.

Some cements contain fly ash and others don't. Otherwise, plain Portland Cement does not have any other harmful additives.

Non-Toxic Thick-Set /Thick-Bed Mortar 

Thick-Bed mortar (also called thick-set or mud set) in it's most basic form is simply portland cement and sand. Custom Building Products makes a mix of 1:3 that is unmodified, it contains no chemical additives like polymers. 

Alternative to Concrete-Based Grout

For something more waterproof check put QuartzLock; this won't be tolerable for everyone. It is a urethane based grout, not cement, and provides more waterproofing.

Non-Toxic Tile Types

I used concrete tiles from Morocco in the picture above. For more info on choosing non-toxic tile types see my post on bathrooms.

Non-Toxic Grout Sealers

If just sealing grout (and not tiles) you can use AFM Grout Sealer (0-VOC, one of AFM's most tolerate products), Custom Building Products grout sealer that many people do well with, less than 1 g/l VOCs. ECOS, a well-liked brand has a stone sealer that can be used on grout. If you don't do well with any of those, you can check out more concrete sealers (which can work on grout) in the last section in the post on sealers.

Sodium silicate (aka water glass) is an idea that gets mentioned a lot among the chemically sensitive. When I spoke with a company that makes sodium silicate they recommended against using this on tiles in the shower. This brand Conkrete-Seal, has been used by someone very sensitive, she said it was somewhat waterproof and she was happy with it in the shower. Technically it's a densifier, and not a sealer, and normally it doesn't claim to make concrete waterproof. It is used in concrete polishing systems like Retroplate and as radon sealers in concrete. It is very benign.

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

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Non-Toxic Glues and Caulks

Updated in winter 2019

Testing glues and silicones was the hardest part of building my tiny house since I did this when I was highly sensitive.

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Non-Toxic Wood Glues

It's difficult to extrapolate a small jar of dry glue to a house filled with it. (In retrospect I would have tested a much larger dry sample.) I smelled them wet because I got a clearer sign of their relative effects on me. Since I have not figured out a better way to test materials, that's what I'm working with. It is often a better idea to sniff something dry as the rate of offgassing and curing can vary greatly between chemicals.

Here are the contenders:

Gorilla Glue - Got pretty dizzy, not good, but not terrible. Seems OK when dry. (Easy to find at hardware stores and on Amzon.)

Elmer's Wood Glue - Not good for me. Didn't test dry. (Carried at hardware stores and on Amazon)

safe healthy 0 VOC wood glues
Roo Glue was the best of the wood glues
Roo Glue - White and wood glue - Not great when wet, but not terrible. Seemed totally benign when dry. This is my top pick and what I ended up using. (Available in the US and it ships to Canada).

Titebond - This is a brand that is recommended for chemically sensitive folks. I had already picked Roo Glue before I got a chance to test it. I do know people that build for the chemically sensitive who use this brand. (Easy to find at hardware stores and on Amazon). I would start here since it's inexpensive and easy to order from Amazon and find in stores.

ECOS Wood glue - ECOS makes extremely tolerable products, and while I didn't get a chance to test this one. I would expect it to be quite good.

Hide Glue is the most natural glue option for wood. It is a strong glue with no VOCs but it is not waterproof. You can mix it yourself from beads or flakes for the most natural option, or you can buy it ready made which does contain additives.

Non-Toxic Caulks

While silicone itself is not toxic, chemicals are added to keep caulking in liquid form are. These chemicals offgas at different rates until the product is fully cured. For silicone caulk, look for 100% silicone, but each brand has different additives which affect people differently and offgass at different rates. 100% silicone is not really 100% silicone, but the chemical additives are not listed.

The replacement silicones can be much more tolerable, EcoBond was a top pick before they went out of business.

All caulks have a chemical odour when wet. I tested them at 24 hours, 48 hours and one week.

I would recommend getting a non-sensitive person to put them in jars and only testing them after they have dried. Note that caulks labeled bathroom or mildew resistant contain a mildewcide. Currently GE I is mildewcide free, GE II contains a mildewcide and DAP makes an aquarium caulk that is free of mildewcides. Any caulk labeled aquarium safe is free of mildewcides.

are aquarium caulks safe and non toxic, no offgassing
Aquarium caulks I did not do well with
AFM Safecoat Caulk - Not the best when wet, not the best at 24 hours, but the best at one week. I used this in my bathroom. It comes in white and is generally a replacement for silicone.

GE Silicone II Clear Caulk - This may a better choice for the exterior. It was not as good at one week as AFM or Ecobond. We used this on the underbelly of my house and on my windows. It is low-VOC. I find that after a couple weeks it is fine for me.

ChemLink DuraSil - This type of silicone caulk is highly tolerable. This company makes great products that you can find at the Green Design Center. I have not tested this one myself but I would expect it to be up there with the most tolerable.

Aquarium Caulks - I have read that aquarium caulk is the least toxic because fish are exposed to it and they can't handle chemicals. I tested two brands, Aquarium Silicone Caulker and one called Marina from a local pet food store, they were much more expensive than brands for home use (for no reason), and they were both the worst of the worst. So bad I would not recommend testing or using these brands. One super sensitive person preferred the Aquarium caulk Aqueon to GE and Ecobond.

Non-Toxic Adhesives

The best adhesive I have ever tested is AFM Almighty Adhesive. I had absolutely no problem and no reaction to smelling it while it was wet. This was a pleasant surprise after all the other glues and silicones. It is a highly tolerable very low chemical multipurpose adhesive. Insider tip, this is the same formula as Build Secure by Chemlink. I used Almighty this to install my shower, on subfloors, countertops and really anywhere this can be used since it's the healthiest adhesive I have found.

Liquid Nails subfloor adhesive is also well tolerated by many.

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

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Non-Toxic Wall Boards & Natural Wall Systems

This post covers:

1. Non Toxic Wall Boards and Drywall
2. Non-Toxic Joint Compounds
2. Non-Toxic Wall Systems
3. Natural Building Systems

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For individual help on choosing the best products and materials for you and your home, you can schedule a consultation with me here.

1. Non-Toxic 0-VOC Wall Boards: Drywall, Gypsum, Cement Board


National Gypsum makes natural gypsum boards that are VOC-free (the paper backed ones). It's not always easy to source and I would rather not have paper-backed drywall.

For easy to source wallboards that are GreenGuard Gold certified, try DensArmor plus, and Georgia-Pacific Gypsum board are all GreenGuard Gold Certified (Densshield tile backer not Greenguard gold).

CertainTeed Gypsum boards and USG Sheetrock claim no VOCs. Research that a very sensitive client did reveal that USG was the cleanest gypsum on the west coast. Some gypsums synthetic and some are mined, and there are different additives used by different brands. For the super sensitive USG Firecode X is recommended (it does not contain a flame retardant, it does contain glass fibers).

AirRenew which is also GreenGuard Gold, claims to soak up formaldehyde. However, it contains a biocide which is likely not healthy. It is a little harder to source than the ones above and some have reported an odd smell with this one that indicates an additive used to soak up formaldehyde might not work for everyone.

Cement Boards / Baker Boards

Magnesium Oxide Board claims to be VOC-free, but not all of them turned out to be. This is a cement board that is more prone to cracking than regular drywall. Many people have reactions. There are many new brands trying to fill the gap for well-controlled production, but there are also many problems coming to light. I list the brands out in the post on bathrooms.

Cement backer boards as well as specialty foam based baker boards for behind showers are also listed out in the bathroom post.

Joint Compounds / Drywall Mud

For regular drywall, drywall mud (spackle) that are zero-VOC are USG Sheetrock Brand Lightweight Setting-Type Joint Compounds – EASY SAND 20, as well as 30, 45, 90, 210, 300.

Proform drywall mud is extremely low VOC (considered "zero").

There are many 0 or extremely low VOC drywall muds available at regular outlets. The powder form is lower in VOCs than the pre-mixed. Even pre-mixed can be found in extremely low-VOC formulations but the most sensitive should use the powdered form.

I used Murco as a joint compound and found it totally tolerable but it is not compatible with MgO board. It has cracked at the joints which is something other builders have noted as well. This compound is compatible with MgO.

2. Non-Toxic Wall Systems

The following are concrete and earth-based wall systems that do not offgas toxins and are suitable for the chemically sensitive. Something a little different from the standard timber frame, fiberglass and gypsum boards.
Pumicecrete Walls

A mix of pumice and concrete are poured into forms to create these non-toxic walls. They can be made load bearing with a concrete beam. Test pumice for radioactivity and for odours that it may have picked up prior to installation.

An interesting material making a comeback, HempCrete is blocks made of hemp and a lime-based binder. The blocks are used to form the walls and act as insulation. They are not load bearing so are used with a timber frame. HempCrete claims to not mould, but a natural fiber in a breathable wall is not something I would consider mould proof. Consult with an architect to make sure this is right for your climate.
Wood Insulated Concrete Forms

Forms are made of a mix of remineralised wood and concrete. Inside, rebar is used as reinforcement and then they are filled with concrete. Insulative fibers can be added or they can be filled with part concrete and part clay or a non-toxic insulation. Brands include Durisol(Nexcem) and Faswall. Faswall currently the only brand available in the US (2017).
Aerated Autoclaved Concrete (AAC)

Concrete based blocks made from quartz, lime or cement, and aluminum powder. Test thinset mortar for sensitivity. Hebel is one brand in the US. It's not approved in California (2017).
Insulated Concrete Form ICF

Nudura blocks (US and Canada) and Fox Block (US and Canada) are the most popular brands right now. ICF could mean different types of foam with concrete fill, but typically it is EPS. See my post on Insulation for a detailed review of EPS. Nadura has a dye. Both have flame retardants.

Is Concrete Non-Toxic?

Portland Cement should be used and it should be confirmed that it is free of admixtures such as air
entrainment and water reducing agents, accelerants and retardants, and super plasticizers. 

Ceramic Cement (Magnesium Cement) is also generally a non-toxic option.

 Which Concrete Aggregates are Chemical-Free?

Natural non-toxic mineral aggregates should be used. Toxic aggregates include crushed brick, crushed 
sandstone, concrete slag, fly ash, cinder, and volcanic materials other than pumice. (Source: Prescriptions for a Healthy House).

3. Natural Building: Earth Based Walls

Cob, Adobe, Light Clay-Straw, and Straw Bale and Rammed Earth

Adobe house from
These are all different types of walls made of clay, straw, and sand. But instead of giving a comprehensive overview I will comment briefly on the suitability of these building materials for the chemically sensitive. Houses made of all natural materials feel great to be in and there is no need to worry about any offgassing. However there are precautions that should be taken to avoid mould. These types of builings might be best suited to dry climates so that there is no chance of mould forming. Some people seem to be doing very well in adobe houses in the south-western US.

If straw is used in the walls it should be carefully sourced to be free of mould and pesticides. When building with cob, adobe or light clay straw there needs to be a dependable dry season of three months for the walls to dry out properly. They are particularly suited to be heated with wood stoves as that dries out the walls well in the rainy and damp seasons (source: Econest). An above grade stem wall and proper drainage around the house is also very important to keep the walls from getting damp.

I'm hearing some bad stories of mould forming on cob and straw bale homes in cold climates.

Rammed Earth from

Another natural wall system worth mentioning in a little more detail, Rammed Earth, uses sand, gravel and clay and has had an interesting development recently. Foam has been added for insulation and steel for support, and 5-10% cement is added to the clay mixture. It's called Stabilized Insulated Rammed Earth.

Water does not penetrate the walls, however concrete, especially when not climate controlled is extremely prone to mustiness.

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

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Heaters for the Chemically Sensitive - Low Offgassing Options 2019

Types of Heaters 

Generally space heaters with fans are the most difficult here are some other options organised by type. 

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Heat Dishes

Optimus dish heater is a type I have used before. Others very sensitive have found that this type of heater has very little to offgas and does not take a long time. It does burn things if it is too close to objects that is a risk. There are a number of brands selling similar dish style heaters on Amazon.

Ceramic Heaters

For the extremely sensitive, universal reactor, the Ceramiciruit portable space heater is the way to go. This is the most tolerated that I have seen, and I have not seen anyone not tolerate it yet. But it is very costly at $988 plus shipping (approx $50 to ship to many parts of the US). If you are not a universal reactor I would try some of the other options from Amazon first.

Quartz Heaters

The next best tolerated type is quartz heaters. Some sensitive folks have recommended the Optimus tower quartz heater. There are other types of quartz heaters, but simpler is better. Optimus also makes a lower profile version that others have liked.

While space heaters with fans are not always the top choice, I have used some successfully with a few days of offgassing. Other sensitive folks have found this Vornado series (VMH10  to VMH600) to be very good.

Convection Heaters

The Patten Utility Heater was tolerated by someone who could not tolerate other convection heaters after some offgassing. It has been reported as noisier than others. There are a number of metal housing utility heaters. Some report only needing a couple or few days to offgas them.

Dyson, heater/fan/HEPA filter is also well tolerated by some.

Radiator Heaters

Oil filled radiator heaters are used by many. The oil is well sealed and should never leak out. I have seen it happen once but that is a major defect and failure. They look inert but they do offgass through the small vents in the front piece. Depending on your level of sensitivity I would say these heaters need to be offgassed for a while. Not having the noise of a fan is a plus for most people. You can find inexpensive versions. If you plan to run this and offgass it for a while, I would get a good quality one so that it will last you a long time.

Other Ways to Keep Warm

Heating blankets (can take a very long time to offgas), biomats (a little more tolerable and supposedly lower EMF) - those two won't work for the most sensitive. But the most tolerated plastic water bottle, Japanese Yutanpo metal water bottles might (buy them here in Canada and here in the US). It's a good idea to have emergency hand and feet warmers (really good to take out with you or for power outtages - I find them totally non-toxic).

Direct Vent Propane Heaters

Can be tolerable for many as the propane is vented.

Mini Split Heat Pump

This unit does not exchange inside and outside air. There is not much offgassing compared to other heating and cooling units.

Carl Grimes suggest it new AC equipment like heat pumps have an offgassing odour than it can be from heavy oil on stamped metal parts. It can be removed with a petroleum solvent, rinsed with hot water plus a non toxic detergent, then water only.

Keeping a mini split heat pump mould-free: 

There is some debate on whether a mini split can be kept clear of mould. I find these units easier to keep mould free than any other type of AC. The unit should come with a fine mesh filter on the front, once you take off the front panel you can access the coils. Keep that filter clean. I never got dust and mould on the coils. If your coils start to get dirt, grime or mould clean them. Make sure your unit is easily accessible. You spray the coils down with water and a cleaning products. Companies can do this part for you.

If you are there for the install, make sure the condensation tube is not too small. It should have a straightforward route out and where it empties should be easily accessible for you. You can pour hydrogen peroxide down the tube you can also blow it out with pressure or suction it out. Don't wait until it's plugged and overflowing to clean it. If that becomes mouldy it may be impossible to perfectly clean so preemptively cleaning it is a good idea.

You could ozone the unit a couple times without damaging it.

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

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Using Ozone to Kill and Denature Mould

The Effectiveness of Ozone Generators on Mould, Mycotoxins, Fragrance and Smoke 

Ozone kills and denatures mould on surfaces, eliminates many VOCS and odours such as perfume. It can also remediate smoke smell in certain materials. 

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For those who prefer a video format, I have explained the process of a shock treatment and the risks in this video.

For individual help with using ozone safely for your application, you can schedule a consultation with me here.

Does Ozone Denature Mold and Mycotoxins?

Some say that ozone kills mould spores but does not denature the toxins (EHC). These two studies show it can denature the toxins. Based on these two studies (that use very very high amounts of ozone), and the experience of me and those extremely sensitive to mycotoxins left over after remediation, I do think it is accurate to say ozone actually kills and denatures mold. 

It can still be a good idea to HEPA vacuum after ozonating to clean up dead spores. 

A shock treatment is either a very high doses for shorter amounts of time or very long treatments (from 24 hours to 48 hours). You really have to experiment if you want to denature mould and see what works for you, and be prepared for byproducts (discussed more below).

Which Ozone Generator to Use

I started with the Jenesco Ozone Generator with an output of 100-2100 mg. This is a high quality unit with a timer and dosage control. 

I liked this unit because it's well made and, the timer settings and dosage control setting were useful.

This one comes in around $400

I have have little Airtherial 5000 mg one (pictured left) this is the lowest cost one I have seen. If you are doing a shock treatment for mould you need one with a hold setting like this one. If you are using it at low amounts for fragrance you will only need the basic timer. You cannot control the dosage with these little inexpensive ones but you can find them for under $100 on Amazon.

For only a little more than a hundred, you can buy this Ivation model which can dial down the dose from  6000 mg to 500 mg. This is what I would use for going after fragrance and smoke as well as cleaning product residue. You don't want a high dose for that application.

Results with Offgassing, Mould, Fragrance, Smoke


- Chemical smell in Camplite trailer reduced after a few treatments

- Glue smell reduced in brand new metal cargo trailer (this seems to work really well o the new glue smell in basic trailers).

-I would not use this is a new house or conventional trailer (that is full of plastics and upholstery) to reduce offgassing, it's too risky and does not work that well


- Mould remediated in all metal trailer after 48 hours high dose

- I also had a mould problem in another house I was living in. After the mould was remediated I was still very sick - throat swelling, extreme POTs and terrible insomnia. I then ozonated each room for 24 hours with the machine and was able to come back without any symptoms. I removed all the fabric and cushions from the area before ozonating and there were no adverse chemical reactions with the wood or anything else in the house.

- I've used it 4 times now in post remediations with a 24-hour shock treatment. This for me definitely denatures mycotoxins. I have also done 48 shock treatments in metal trailers that were very effective. (I let in oxygen during that time).

- However one of these times the 24-hour treatment created horrible byproducts in a wooden house. Even after excessive airing out I got extremely sick. It seems as though I overdid the ozone or did not have enough oxygen coming in. Big risk here. It was a long time before I could go in that house again.

-Some people found it useful to shock a room or tent, and to "flash" belongings before any mould toxins could take hold.

Fragrance, Smoke and Funky Smells

Smell removed from funky smelling fabric (towel that had a smell that washing would not remove). 

- BUT: gave some fabrics like wool and cotton a strange smell when doing an intense 24 treatment 

-Ozone can help a lot with fragrance in a car or house as well as smoke smell. Car dealerships use ozone but not super high amounts of for long amounts of time. 

-This is very useful if fragrance and smoke smell are your big concerns. Go low and slow on fragrance, cleaning product residue and smoke until you start to see a difference. 

To remove odours the time needed for treatment is much less than the shock treatment for mould. This will reduce a lot of the risks. Car detailers run ozone for 15 min to 2 hours, typically, or until they can removed the smoke or other problematic odour. 

You have to be sure you are using it safely and understand the limitations -

How to Use Ozone Safely

- Ozone is a very toxic gas. People and pets should not be in the building when an ozone machine is on. Do not even take one whiff of it. Make sure you have a plan to turn it on and off while holding your breath. Ideally turn it off without entering the room (through the electrical panel). It clings to your clothes even if you hold your breath and walk through - this is not safe.

- Ozone needs to be 5-10 x above safe levels for humans to impact bacteria and mould (Pinto).

- The place should be aired out after using ozone to make sure that the gas is not inhaled. Ozone is unstable and will dissipate, but it does not dissipate as fast in a closed space with no air flow. If other VOCs form (see below) then it is necessary to air out the place for a while. The half-life of ozone is 40 min-25 hours. If byproducts have been created then give it a few days at least. Make sure there are tonnes of open windows for the air out.

- One reason government health sites do not recommend the machines is that the shock treatment used to get rid of mould toxins is a very harmful level if inhaled (deadly if you stay in there). Even the low levels recommended as safe by some manufacturers is probably harmful to anyone sensitive to toxins. So there is a huge risk if someone does not know how to use it safely. It is possible they are also wary because of the negative reactions outlined below. In many conventional houses, it might not be possible to avoid all those secondary reactions with materials.

Limitations of Ozone 

- Ozone cannot remove carbon monoxide or formaldehyde (EPA).

- It cannot get into porous materials to remove mould or chemicals (EPA). My experience suggests that it does denature mould that is near the surface of pourous materials. I don't think it goes very deep.

- It will not help with chlorinated hydrocarbons (vinyl, plastics etc) (EHC)

- May not work on clothes and shoes (Pinto). My experience is that there is a bad reaction with any fabric in high amounts. 

Negative Reactions and Byproducts of Ozone - What Can go Wrong

Ozone reacts negatively with some compounds creating more VOCS. Some of the substances it reacts to are:

  • New carpets (EPA)
  • Active tobacco smoke (EPA)
  • Terpenes (to form formaldehyde) (CDH)
  • Styrene (EHC)
  • Floor finish that contains pinine (Pinto)
  • Ceiling tiles (from a client of mine) 
  • Old carpet (from a client of mine)
  • Fabrics (from my experience)
  • Wallpaper (from a client) 

I have found there is a negative byproduct left with almost every porous material if you do this in high enough doses for long enough.

High doses of ozone used to really clear out mould toxins will also degrade or harm certain materials such as:

  • Plants
  • Rubber
  • Coating of electrical wires
  • Fabric
  • Some Artwork
  • (EPA)

My experience is you really need to do many many treatments before you start breaking down most rubbers.  I have done many high dose (shock treatment) ozone treatments and not broken down coatings on electrical wires. 

How to do an Ozone Shock Treatment

For a shock treatment, remove everything fabric or wrap them in plastic, this includes mattresses. 

Remove plants, pets, and artwork that is not behind glass. Tape up electrical outlets. Remove all electronics. Make sure you have everything you need before turning the machine on. 

Hold your breath while turning it on and while turning it off. Air out the place with fresh air for 24 hours. This is based on my experiences. 

Make sure you research if this is safe for you and worth the risk. Understand why the EPA does not recommend it. It is too easy to do something wrong where you could breathe some in. Treat it like the deadly gas that it is. If you are not sure if it will react with your carpet, walls, ceiling then it is a last resort treatment. You can also test a low dose first to see if any weird smells form.  

Make sure it is dosed correctly for the space and if running it for 24 hours it needs an oxygen source. Overdoing it can make your place intolerable. I recently had a bad experience where I overdid it with the ozone, it took a month to be able to go back in.

How to Dose Ozone

I generally use 3500 mg/hr in a single medium sized or large room for a shock treatment. A shock treatment which is what kills and usually denatures the mould is usually 1000 milligrams per hour (mgph) per 100 sq feet (at 70 degrees with relative humidity at or below 20%). The level you are aiming for is 6 to 10 parts per million. Many people shock for 1-3 hours but those of us super sensitive tend to keep going until the substance is denatured. I have gone as high as 5000 and 7000 mg/hr in a very small trailer for 24 - 48 hours. 

The machines I like are the Jenesco Ozone Generator with an output of 100-2100 mg. And the little 5000 mg ones on Amazon that are low cost with a "hold" setting.


Michael Pinto:

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

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A Guide to Non-Toxic Camping Gear (And Keeping it Mould Free) | 2019

I am updating this post after having spent 2 years of close to full time camping. The focus is still on avoiding chemicals, but I am adding more unusual camping equipment and techniques for avoiding mould, updating new gear I really like, and some new tricks.

I recommend all the products in this post most of which I have used or are recommended by other sensitive folks. This post contains affiliate links wherever the brands I like have an affiliate program. Upon purchase, I earn a small commission at no extra cost to you.

For individual help on choosing the best camping gear for you, and how to keep it mould-free, you can schedule a consultation with me here.

Choosing a Tent Type

A Cheap and Easy Start - Pop Up Tents

non-toxic pop up tent, offgassingI bought an pop up tent as my first tent. I went for one of the cheapest options here just to get started quick. I was able to use it after one week (with the doors all open at first for air) but it was about 1 month before I found it offgassed the chemical smell, and I could close up the doors. I was super sensitive at that time.

A number of brands have pop up tents in this style which are super easy and quick to put up and have a decent design in terms of the amount of ventilation (more on the style I prefer with ventilation below).

Mine leaked in a heavy rain so I don't like this style of tent, other than the fact that it is very easy to pop up and if you get a good tarp over it you will be waterproof - I always put a tarp over, more on that later. Anyone super challenged with putting up tents might want to start here.

Rain Fly Styles - Preventing Mould and Avoiding Chemicals

For a heavy rain, a tent with a really good rainfly is needed that comes down almost all the way to the ground like many of the REI or MEC brands and this Backpacking tent (pictured left). I used the Winterial version of this style for many months. When it comes to tents on the ground, this is the main style I look for because of the good rainfly which keeps it more waterproof. Having mostly mesh on the inside also reduces your exposure to chemical offgassing and helps to prevent condensation on the walls.

Technically you don't need a tarp over but I always add one. Water that soaks the tent walls will then soak anything that is touching the walls inside. The tarp is also needed so you can get in and out when it's raining. I just don't trust any tent enough to not put a tarp over top. More on setting up tarps later in the post.

Offgassing Tents

Sometimes the rainfly smells stronger than the tent and sometimes it smells less. Sometimes a super beefy tent bottom is the hardest part to offgas. It depends on the brand.

Some who are trying to reduce exposure to chemical offgassing and flame retardants wash the tents to remove some of the treatments, but this also removes some of the waterproof coating. That can work if you have a good tarp over. I have not found any evidence that many flame retardants can be adequately washed out, but it can't hurt to try. I like putting tents in the sun to offgas them. Smell them to test, and also touch them to make sure they don't cause skin irritation.

The more mesh you have the more airflow and the less exposure to offgassing.

Stealth Camping - How to Camp on Balconies

For stealth camping on patios and balconies of hotels or Airbnbs I have used a one person tent like this, I also like this Tenton brand (I like that it comes with straps to strap it to a camping cot below to raise it up). You can also look for tents called bevy tents.

I have tried just a mat with a mosquito net over it, and I have also just strung up the just the rain fly (with not tent) over a camping cot and Thermarest if there are no bugs.

Otherwise you can cut out the bottom. Never put a tent with a bottom right over outdoor tiles, bricks or concrete for long, you will have a recipe for mould fast. You can put up a tent on top of a camping cot like in the pictures of the Tenton one person tent linked to above. But to keep a low profile I prefer to use a camping cot and then string up the rainfly or mosquito net so it does not go higher than the balcony rails.

Putting up a Tent when Disabled 

Make sure you know how (and that you can) put up your tent alone (as well as set up other supplies like a stove) before you get to the campsite. I have shown up to campsites with tents that are defective or missing parts more than once, so I would do a trial run for that reason as well.

For those who are disabled and limited I made this video on Camping for Those Who Can't Camp, to try and give some examples of how camping might still be possible for you.

Brands of Tents that are Low in Offgassing

Brands that seem to be the lowest in offgassing are:

Lightspeed (polyesters with PU coating) REI (polyester, rainfly and floor coated with PU)
LL Bean (polyester with PU from what I have seen)
Big Agnes (nylon, polyester with PU and some silicone).
The jury is out on Coleman, some people tolerate it and others don’t.
Some people find cheap Walmart tents especially Ozark brand are more tolerable than ones for hundreds of dollars. I have found Ozark tents to be very tolerable myself.

There is no consensus on which brand is the best for those with chemical sensitivities. Everyone is so different, no tent is perfect, and for some less sensitive there might not even be a big difference between the brands. You have to test them out for yourself if extremely sensitive.

Silicone treated tents might be more tolerable for some, others may prioritise avoiding flame retardants.

Tent Brands without Flame Retardants 2019 

Sierra Tensegrity Elite tents (Amazon).
Mountain Hard Ware tents made after 2019 are FR-free (Amazon).
Fjällräven tents (Amazon).
Diamond Brand tents (Amazon).
Nemo Some tents do not have FR. (They say the slicone treated ones don't, you will know because they say they are restricted in some states).
Moonlight (Coated with silicone on the outside and polyurethane (PU) on the inside).
Some canvas tents do not have flame retardants.

Camping Gear without Flame Retardants 2019

None of the Thermarest Camping pads contain FR. Some have the Prop 65 warning (but for chromium)

The Exped mats are FR free since 2015 lot.

REI brand sleeping mats are not treated with FR.

Wildkin sleeping mats and sleeping bags are also FR free.

Two other sleeping bags that are FR free are Holy Lamb Organics (but they use cotton), Kelty, Wiggy's, and the down quilts by Jacks 'R' Better.

Should you go with an Unconventional Tent?

Aluminum Insulated Tents

These Billion Brick tents are insulated and the foil on the inside will also block most of the VOCs from the fabric on the outside. They say you can sleep in them down to 0 degrees Celsius. They are 269 USD. They do not have any mesh for ventilation which I imagine would be quite the problem for condensation and I do not know how you would get fresh air. This doesn't seem realistic for me.

The Shift Pod is another version of an insulated aluminum tent made for Burning Man. The benefit to the aluminum on the outside is it's reflective of sun and heat. I would think it would have similar problems with condensation in most situations. It's pricey at 1300 USD.

For 18 USD you can get this aluminum lined small sleeping tent (that might work for balcony sleeping or in an emergency, otherwise it's difficult with a lack of ventilation). The aluminum on the inside is more tolerable than the usual plastic.

Make Your Own Tent

Others have made homemade tents with materials they can tolerate like Tyvek, Reflectix or XPS sheets. More info on that in this post here. You can also make a more typical tent from untreated nylon.

Canvas Tents Prone to Mould

Some folks who cannot handle the chemicals in the synthetic tents have tried canvas tents. These do not hold up well to rain and high humidity and I would not use them in rainy or humid conditions nor expect them to last very long at all. Some companies people like are Reliable Tent and Kodiak Tents.

For those who don't tolerate cotton or who want the tent to hold up a little longer than cotton canvas, you can make one out of hemp fabric, like this one. You can expect cotton and hemp to last a short while in dry non-humid climates where you are expecting very little or no rain for a while.

If you are making your own tent out of canvas or nylon you can use the tube structure of a conventional tent and build it around that.

How to Stay Dry and Prevent Mould when Camping

how to set up a tarp over a tent to stay dry and prevent mould
Always put a tarp over a tent

How to Set up Tarps Underneath and Over Tents 

I bought a tarp for underneath to keep dew from getting the tent wet from below (also called a footprint), and later I added a tarp for over the tent to stay dry. The bottom of my tent stayed nice and dry at first with the tarp underneath. I would take out and turn over the sleeping mat every day. If the bottom of the tent gets wet you will want to dry it in the sun within 24 hours (flip it and then put it back and maybe move spots). You can use the footprints made for underneath tents but tarps are generally cheaper (your tent may come with a footprint).

You want the tarp underneath to be a little smaller and tucked in so that is is under the tent. No water should get between the two. Some people tuck it and then raise it a little with sticks or rocks so that no water gets in between. I tried that but in the end tent bottoms still went mouldy on me if I had damp soil.

Putting a tarp overtop helped a lot. I found regular tarps from the hardware store has a strong smell but offgassed within a few days. I use a silnylon tarp which has a less offensive odour but is more expensive. Over most tents you need 12 x 10 or 12 x 12.

Some people find they still do have to move the tent every couple of days due to condensation or the earth going funky underneath. Keep a backup tent that is offgassed in case of mould or damage to your primary tent. Keep backup gear especially if you are out in the wilderness, if you need geat to offgas before using, or you cannot easily drive somewhere and buy new gear within one day.

Generally you string up the tarp up in an "A shape" so that it's touching neither the tent nor the ground, you can also string it up with a shed slant like the photo above. Some people dig a small trench around so that the water that drips off does not go towards the tent. Without a tarp I had a lot of problems including saturation of the tent and water coming through especially where anything was touching the tent.

In a major storm a larger tarp over head helps, as well as a deep trench, and if things are going swampy you need to raise it up. I have used XPS sheets to raise up a tent in a storm before I found the Cot Tents.

The Solution to Tent Bottoms Going Mouldy - The Best Tents For Avoiding Mould

The perfect tent in my opinion
After throwing out many tents and then moving on to cutting out the bottoms, I have finally found what seems like the perfect tent: the Ozark Trail Two-Person Cot Tent (easier to find at Walmart Canada than in the US right now). This is an integrated camping cot tent (pictured left). This is off the ground so the bottom will not mould. They do have the one person version available in the US. This had a very low odour rainfly and a brilliant design with the rainfly coming down way past the cot to protect water from getting in between. This is the best design of a tent I have ever used, though it's flimsy and broke on me when I took it down. It is assumed here that the Prop 65 warning here indicates the flame retardant "Tris".

Although I didn't like the more common style of tent cot (I had trouble with ventilation and even dangerously spiked my C02 levels one night), if the Ozark Tent is not available I would use this style again, but with caution with ventilation. The Winterial brand is a brand I have done well with, though it was the Camp Rite brand that I tried in this style. The Camp Rite brand does have a two person version.

I quite like the Tenton tent that is made to strap on to their XXL camping cots. You will, as always, want a tarp over this whole set up since this rainfly does not come past the cot (though on their website they sell a larger rainfly which would).

The tree tents look interesting, as they are raised off the ground, but you have to keep in mind these are really just for sleeping as they don't look very conducive to hanging out all day. I wonder how much they sag in the middle, and they are not as easy to put up. For those who are less picky about their sleeping environment resembling a regular bed, the hammocks with nets are interesting options that are affordable and easy to travel with.

Downsides of Cot Tents

Cot Tents are Bulky

While I would never want to go with anything other than the raised off the ground tent again, this won't work when I travel. When I travel I need to fit a tent, sleeping mat, and sleeping bag into a duffel bag. The sleeping mats I use are huge and unless I can send a tent ahead I would have to go back to cutting out the bottom. I would use plastic bags to encase things instead of the thick tarps I mention.

Cot Tents are Colder

It is cooler when you are raised off the ground. But I don't find it any worse than cutting out a bottom and using a camping cot (in fact I find it warmer than tents with the bottom cut out).

Flame Retardants

Ozark is a very tolerable brand for MCS. I don't like the flame retardants they use. I have not seen a flame retardant free brand in this style.

Should you Buy a Cheap Tent or Tent that Lasts?

For those doing mould avoidance or living somewhere very damp you might want to go with the more disposable option. Expensive tents from REI and MEC tend to pack smaller and lighter and should be higher quality, however, if they do go mouldy it is a bigger loss.

On the other hand, if I am travelling with a tent I want one that's not going to break unexpectedly as many places around the world do not have stores that sell tents. Check also how much wind and rain they say they can withstand. You pay more for quality and wind and rain protection.

But all of that said, I would never spend more than 150 on a tent unless I'm sure it's going to last me a long time (like the ones raised off the ground).

Camping Mats that are Comfortable and Low Offgassing 

Air Mattress

I started with the Lightspeed air mattress which is the one the most sensitive to chemicals use. It offgassed quickly (2 days in the sun) and felt comfortable. It's good quality but I had back problems with it. Many with chemical sensitivities prefer the Intex polyester air mattresses.

Other very sensitive folks have tolerated the small air mats. I was very impressed with how little this one smelled (less than the air mattress), and it's a WAY better option to travel with, but I did not find it comfortable enough. Go with the simplest, most compact option that is still comfortable for you.

Open Cell Foam Self Inflating

My Mondo King
I ended up buying the thickest Thermarest instead and LOVING it. This is as comfortable as a bed to me, though many people put Thermarests over a camping cot, that seemed excessive with the MondoKing (though cots can also help you get off the ground which is a benefit when you have cut out the bottom or are preventing mould under the bed). I’m not that picky about beds so I was surprised that the airbed hurt. The Thermarest has a decent R-value to keep you warm, the more insulation you have under you in the cold the better.

The MondoKing is very comfortable and I usually wake up forgetting I’m in a tent. It has polyurethane in it but it offgassed quickly in my experience. I used it after 2 days of airing out (not ideal), in one week I found it to be really good, and one month to be near odourless to me. This is a super good mat for a trailer or other tiny home as well. It does not contain flame retardants.

I bought the repair kit for the Thermarest as well because this is going to be my main bed in the trailer, I also carry the repair kit when travelling.

I still prefer the MondoKing, but another good and more affordable (but thinner option) I use is the Lightspeed version.

Beds and Moisture

When it was hot and sunny (and I was not self-contaminating) I had no problems with condensation if I turned it every couple days and some days left it standing up to air out. You will want to flip or air out your sleeping bag as well in the day to prevent mould.

As it got cold and I moved it into a trailer it became very challenging to keep a sleeping pad dry and mould free. It needs to have slats underneath and a waterproof cover without a doubt in a cold or damp environment. I wouldn't recommend leaving this on any flat surface without a waterproof cover anymore. As I got more sensitive I was not able to keep this clean without an encasement.

If you are very sensitive to mould, very unmasked, or detoxing through your sweat, encase the sleeping mat right away. You can use plastic but I prefer these thick aluminized tarps as they also block the smell. I used those tarps if I needed to block the smell but if I just needed to encase it I used contractor bags which are thicker than the usual garbage bags. I taped it airtight.

Closed Cell Foam Pads

Safest bet
For the ultra sensitive to chemicals, an aluminized Thermarest is the safest camping mat. People usually go with the solid foam or the small inflatable ones as they pack much smaller than the delux one I bought and are more affordable. They offgass less as well. Here is a good overview of the closed cell foam pads.

You can wash these unlike many of the other options. Some even pour boiling water on them to clean them and kill bacteria.

Camping Cots 

I like this style of camping cot the best because it packs really small, it is relatively flat, works well with a Thermarest over it, and it's low to the ground but high enough to have air flow. I never put a camping mat straight on the ground anymore. I would not say this style of camping cot is that easy to take apart and put back if you are physically disabled.


Sleeping Bags

I'm extremely pleased with this sleeping bag which is warm and offgassed after sitting in the sun for a week or so. I never even washed it. I used this in the summer and some days it was too warm. I am currently using this bag, as when it's on sale it's a better price.

Others like a silk sleeping bag liner which keeps you warm and keeps your sleeping bag cleaner. It is much easier to wash a liner than the sleeping bag. I'm using this silk one and it's quick to dry (surprised by how chemically it smelled, needed more washes than most fabrics). You can also make a liner by sewing a queen flat sheet in half. You can either use a liner to get inside of first or to encase a blanket. This will keep the sleeping bag good for longer. The polyester liners can work too.

In warmer weather I skipped sleeping bags and used heated blankets as my only blanket. As I started to detox through my sweat things got trickier. Now I like a warm but washable option like these Pendleton Blankets. But, when is is very cold, a sleeping bag is really the warmest option.


I use these AmazonBasics polyester sheets. But there are specific sheets for Thermarests and other brands of sleeping mats. They are also polyester, the only difference is they are fitted exactly for the Thermarest. You don’t want any cotton in your tent - it doesn’t do well outside for long if it's humid, and it's terrible when wet.


I bought a polyester camping pillow which is small (and it has cotton on the outside!) I use waterproof pillow cases to prevent mould which I aired out and washed before using. They do smell at first, but polyurethane coating does offgas (to most people's standards).

I have tried lots of camping pillows from the air and foam ones to the polyester ones, to just using a towel. You have to figure out which is the most comfortable for you. Some are very small. The air ones can be easy to roll off of. A towel is easy to wash if you need to wash gear often.

I keep backups of everything.

Staying Warm and Cool

Heated Blankets

I use a heating blanket in almost every climate. I thought the biggest problem for me would be stabalising my temperature but that ended up not being that difficult at all. This is the Sunbeam heating blanket I use. After going through a lot of these, the trick is I want one big enough to cover me and I want the 10 hour shut off not the 3 hour shut off to keep me warm all night. They are challenging in how strong they smell when new and since they can't go in a dryer they can be difficult to clean in cold weather camping.

I encase my current one in these liners and wash the liner every 3 days. For those concerned about EMFs you can use this to heat the tent without putting in on your body. It won’t be as warm, but it is likely safer than a stand-alone heater in a tent. Or, the fancier and supposedly healthier option is an infared mat.

This 60 watt heated blanket (the smaller throw size) will run for most of the night off this solar kit. I always have an extension cord running to my tent. A small heated blanket tucked into a sleeping bag can provide a lot of warmth.

Other Heating Options

Hot water bottles can be put inside the sleeping bag at night. This thermoplastic one has been reported to be very tolerable by many. When you don't have electricity, hand warmers in your sleeping bag can be a big help, the same company also makes sock liners. I have used these in power outages, they seem totally non-toxic.

Battery powered heated jacketssocks and gloves can be a huge help as well.

Some people do use wood stoves in a tent. I'm getting the Cubic Mini for the cargo trailer but I do not have experience setting up a wood stove in a tent.

Using a Heater in a Tent 

I have set up many a small heater - I check the wattage and if it has temperature control (I make sure my tent is big enough, note: read the tent dimensions carefully, they run small). It's safer to place the heater up on a small table or round of wood to keep it from knocking over or blowing directly onto something that could melt or burn, I make sure the tent is big enough to accommodate a heater with lots of space around it and it has an auto shut off when it falls over. I use this little Honeywell heater because it's super low wattage (250 watts). I find it easy to accidentally shove this when sleeping and it can turn towards the tent fabric easily. That is just one reason why this is not technically recommended.

If my tent is on the ground and I have a thick Thermarest, I can be warm enough with a heated blanket and that little heater down to 5 degrees C. I don't sleep well when I'm cold, but everyone is different, so you will have to work out those details.

AC in a tent 

For the AC you will need to cut a hole for the exhaust and seal with tape around it. If I put any thing electrical in a tent I make sure I have multiples layers of protection from getting wet from above or flooding from below.

Use heaters, heating blankets AC or woodstoves at your own risk of fire or electrocution. They are not recommended for tents.

My Favourite Unusual Camping Supplies

Other items I use for camping:

- I cooked everything in an Instant Pot when camping which I could do on my one extension cord

- Travel Berkey is still on my wish list, this ceramic filter is ideal for well water or any other water where filtering for biological pathogens is the priority, otherwise I buy water

- Non-cotton fast drying travel towel, I use this one.

- Ear plugs, and for really loud situations the "triple down" method of foam + silicone + ear protectors (or noise cancelling headphones). The construction ear protectors do smell quite strong. One benefit of noise cancelling headphones is some noises cannot be blocked without adding white noise.

-The foam contoured eye masks smell a littel and need some time to offgas (I put them in the sun). It is still my favoutire mask many years later. The fabric ones can be washed to remove chemical treatments. I always keep a backup mask.

- I still love this portable dryer, I got a tonne of use out of that. I used it outside with an extension cord under cover.

-Washable wool or silk long underwear, wool socks and wool hat, gloves to stay warm in cold weather

-Hand sanitizer (that's my favourite non-toxic brand) and baby wipes are essential in a tent (unscented of course, for yourself and also if there are bears around.)

More Resources

My guide to a mould sabbatical

Avoiding flame retardants

EI Wellspring Safer Camping - How to choose a campsite with extreme MCS

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

I spent 2 years living outside in tents in order to bring down my chemical and mould sensitivities and get back into regular housing.

Thank you to Emily Snelling for content support in the early days of camping and the members of Mold Avoiders on the Road for all the advice along the way.

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