The Best Air Purifiers for Mould - A Review of PCO Machines

PCO Air Purifiers - Which One I Use and Which Ones are a Scam

PCO (photocatalytic oxidation) is a technology that breaks down mould, VOCs as well as some pathogens. My interest in these air purifiers comes from first-hand accounts of this helping people with mould and VOCs and from the studies showing the eradication of mould and mycotoxins.

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This is a technology that is extremely promising for those sensitive to mould and it's important that we test this out as much as we can. There has been so much talk about HiTech (both good and bad, which claims to be PCO) but very little talk about the more recognised and more affordable brands - I'm really urging the mould community to gather more data on this by trying some of these other models.

I am really excited about this technology as something that can safely break down mycotoxins and odours. Some people may be interested in its effects of breaking down viruses and bacteria as well.

A very brief explanation of PCO is that UV light hits a catalyst, usually titanium dioxide, creating hydroxyl radicals (OH). These OH molecules bind with and break apart pollutants into harmless molecules.

What I'm Using

I use the Vornado air purifier. The Vornado PCO300 ($260) and PCO500 ($470) are the air purifiers with a great value. It is a PCO air purifier plus it has true HEPA and activated carbon. Most PCO units are much pricier or don’t include all three air purification methods.

True HEPA and activated carbon capture dust, pollen, pet dander, smoke, bacteria, mould spores, dust mites and odours including VOCs. PCO and carbon are the main technologies used to reduce odours and VOCs. (Ozone can as well, but it is very risky, I have a post all about ozone). PCO actually breaks down molecules including moulds. I like that it has all three main air purification methods.

Why I chose this machine:
-The PCO component has true UV and titanium dioxide
-Respected brand
-Noticeably brings down odours in new apartment and new cargo trailer
-Has a 5-year warranty
-Replacement parts are reasonably priced ($25 bulb every year, $35 titanium dioxide screen every 5 years - for the PCO related parts)
-Does not put out ozone

What I don't like about it is that the unit itself offgasses, though not everyone thinks so. After two weeks I found it to be good.

The difference between the two sizes is that the 500 has a lower low speed and a higher high speed. The 500 has 2x the HEPA and activated carbon of the 300. They both have the same PCO technology - so if you want to increase the effectiveness of the OH molecules in a large space you would want two of the 300 instead of one 500. The 500 moves 184 CFM and is advertised for 265 sq ft - around 5 air exchanges per hour.

Some other PCO units are more or less the same unit re-branded: Continental Fan CX1000, Catalytic Pure Air, Field Control Trio / Sun Pure SP-20C. They seem to use a very similar PCO catalyst style to the Vornado with a titanium dioxide plated metal screen.

Another brand that is very affordable that also incorporates HEPA, carbon and PCO is GermGaurdian. I have heard of people using it in trailers and being happy with. At $89 it's a steal. And it has 5.5 ACH in 171 sq ft.

I will review a few other brands that I ruled out for myself: Air Oasis and HiTech, as well as Airocide and Molekule.

Air Oasis

The Air Oasis 3000G3 model ($500) is rated for 3,000 sq ft and only moves 11 CFM of air.  3,000 sq ft at 11 CFM is 0.02 air exchanges an hour. That is very little air movement.

Note on air exchanges per hour (ACH) - this is a key area of comparison with air purifiers  ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends a minimum of 4 ACH for patient rooms in hospitals, 5 for intensive care units and 25 for operating rooms. For the purposes of those extremely sensitive to mould and VOCs we want about 5-10 air exchanges per hour. This Air Oasis has 0.02 air exchanges per hour. (I am using 8 ft ceilings in my calculations of CFM to ACH.)

Air Oasis does more than just PCO it also, as the company states, “creates ionized hydro peroxides”  (AKA it's an ionizer) which puts out ozone and does NOT meet the California regulations on a safe level of ozone (CARB). You can have one made without the ozone production component.

It has a 3-year warranty and the replacement parts are $80 every 2 years.

I know this brand because it is being promoted by top doctors. I was surprised when I dug into it to see how ineffective it would be at moving air, and that it gives off unsafe levels of ozone (as determined by CARB). There is more of a discussion of this brand and their technology in the comments as this machine claims to be doing something different than just PCO or just ozone machine.

HiTech Air Solutions

The inside of the 110 model $5995
HiTech Air Solutions, a brand known among extreme mould avoiders, makes Air Reactors that claims to be PCO machines. To start, the 101 model ($2000) is very expensive relative to the other PCO machines. From looking at the inside of the machine they use basic components that total under $150 for all visible parts: four foam/coarse dust filters, two UVC lights, two computer fans, and a 4U 19" rack case. The claim here is that some of these filters are photocatalysts that produce OH molecules - that there is something invisible called "Technosite®"  (no evidence of this trademark with USPTO) impregnated onto the filters. They may be using something similar to PALCCOAT (confirmed not partnering with this brand) which is a clear titanium dioxide catalyst (FYI $13 per square meter). I have found no evidence of a patent held by HiTech or Ray Robison (owner) on anything in the machine.

(I have also seen two other odd claims from sales reps of the company - one, that the filters are coated with Sporax and that both the filters and the bulbs are also coated with something proprietary - both things that I would want to know are safe to use with UVC light).

HiTech claims to be doing something different than the others. They claim their OH molecules (which are produced by the PCO process) last much longer in the air than the other air purifiers' OH molecules (~6 weeks instead of ~15 seconds) based on "a study by Texas Tech", though this study cannot be produced by the company. Dozens of phone calls were made to track down the existence of this study and nothing turned up. Even more, the University claims it does not conduct studies give the results on the phone and then withhold the report for large sums of money (as the reps claim). I have not found any evidence that this produces a totally different kind of OH molecule.

I would like the company to disclose what they are using in this machine so we can know if it is safe and effective, or, provide the studies that show which molecules and byproducts this machine produces. The burning smell is worrisome to me. The accounts I have seen of bad reactions are also worrisome.

HiTech claims it produces 99.9% pure air. I have seen no studies to back up this very broad claim. What is the level of contamination in the air to start, and what is "pure air"? Also note, PCO technology does not filter particulate pollutants (EPA).

I have contacted a technical rep, sales rep and the owner for these studies - they responded but were not able to provide them. Others interested in this company have contacted them as well for this information.

The HiTech 101 is 142 CFM and claims it can be used in 1600 sq ft which is only 0.7 air exchanges per hour. Their bigger units are ~$5000 and ~$6000 dollars. The HiTech sales reps make 25% commission off each unit and they usually recommend multiple units for houses. The commission for the three sizes is roughly: $500, $1000 and $1500. The cost of the replacement parts are $140, $190 and $295 per year, for the three different sized units.

HiTech has not submitted their Air Reactors to CARB to confirm they give off a safe level of ozone. However, the bulbs they are using are USHIO brand UV bulbs with a 2G11 / PL-L base which do not give off ozone. They use another brand as well, LSE Lighting UV bulbs, with the same base. From what I can tell this bulb would not be any different from the USHIO brand.

I’m calling on HiTech reps, especially doctors to consider the following:

-We don’t know what is in the machine - it is invisible, not disclosed, and the company has not backed up the claims of which molecules and byproducts this machine produces
-The company has made numerous unsubstantiated statements - there is no evidence of any university studies, no evidence of FDA approval, no evidence of a patent, no evidence of a trademark (on Technosite)
-I have seen people have bad reactions - it is not proven to be safe
-This machine is an unnecessary financial burden on patients when there are well-established brands selling verifiable PCO machines on the market for a fraction of the cost
-Making $1000+ off each (medium sized) unit is certainly a nice incentive for sales reps, though ethical concerns must take priority

FDA Approval

The FDA approvals I have found are one for a PCO machine involving titanium dioxide (it proved to destroy some bacteria, viruses and mould) for specific commercial uses. The Airocide also has FDA approval. HiTech claims to be FDA approved, I can find no evidence of that. Anyone can search for FDA approvals here.

HiTech did respond to this article, some of the statements have changed from what I have records of and the updates are in the comments.

Other Popular Brands

Other popular PCO machines are Airocide (CFM 14 “Cleans any size room” which I suppose is technically true, but is not going to get you 5-10 air exchanges in most rooms, $600.) This doesn’t move a lot of air, but I like that the website has studies confirming that it doesn’t give off ozone and a short study on breaking down mycotoxins. It looks cool which is a major plus. The claims about removing dust, dust mites and allergens are not all that accurate. PCO machines do not filter particulate pollutants (EPA). It has a 5-year warranty and 60-day money back guarantee which I like. The main drawback here is how little air it moves.
Molekule (CFM 80, 1 air exchange per hour in 600 sq ft, $800) is a slightly different technology called PECO. Here is a summary of their studies - very promising results on eradicating mould. It is very beautifully designed. This company has well respected big names behind the design. The inventor of Molekule is the person who discovered PCO. He has an impressive resume. I would love to try this machine out as I think it is very promising. They are still a new company (started 2016) so I would be worried about the possibility that they won't be around to provide replacement parts. However, I do have a certain amount of faith in this company based on the founders. If it proves to really work well, or better than PCO, then they will do well (their power point they showed me showed it worked better than PCO). The warranty is only 1 year, which is short compared to the others. If you can afford it and design is important to you I would consider this machine.

Both of these require $100 a year in replacement parts.

Most of the PCO machines do not include HEPA and activated carbon like the Vornado, they are more expensive, they don't move as much air, and their replacement parts are more expensive. (Airocide used to have a unit that included HEPA for $800, which is not available right now.)

Adverse Reactions

I have heard of people having bad reactions to HiTech. I have heard only one bad reaction to Airocide, and a couple bad reactions to AirOasis. I do not know what accounts for these bad reactions. It does not appear that there is an ozone issue (apart from AirOasis). I don't have enough data on all these machines to know if bad reactions are more prevalent with any particular brand.

HiTech reps speculate to buyers that the bad reactions may be helpful (some kind of detox or herx) which is ethically unsound in my opinion. With no data to suggest this is detox, we should take a precautionary approach.

I would love to hear from more people who have tried these other brands. Let me know if you have had good results or a bad reaction to a PCO machine (other than to the plastic or glue of the unit).

Since writing I have heard one bad reaction to Molekule and one to Germ Guardian.

It is possible that PCO is creating harmful byproducts in high VOC buildings.

The Burning Smell

According to Airocide the UV bulbs themselves emit a bit of a burning smell at first. They burn theirs in for two days, but sensitive people can smell it for up to a week. The Vornado PCO had a very slight burnt smell at first which seemed like the smell of carbon. HiTech states that the burning smell is mould/mycotoxins breaking down. I see no evidence for this claim. Airocide made a statement that mould does not produce a smell when broken down by OH molecules.

A HiTech user also stated that the UV lights have burnt right through the "reactor pads". This is consistent with a theory that the UVC lights are burning the "reactor pads" and causing a smell.


This post is not sponsored by Vornado. The Amazon links are Amazon Associate links. My recommendation is based on the most affordable and effective product that I have found. Buying your products through these links helps support me and this blog.

This post was written with the technical assistance of an engineer, though the opinions and conclusions are my own.

This post was written June 2017. I do my best to keep all my posts updated if there is new information.

Zero VOC Flooring

This post is organised into three categories, those that are the most tolerable, those that would be OK for most sensitive people, and those that might work for those who are not extremely sensitive. 

1. The Most Tolerable


Wood flooring will always be my number one choice. However,  wood (and many natural aromatic oils) contain terpenes which are problematic for many people.! For those sensitive to the smell of wood this is not a good option. Aromatic woods like pine have much higher VOCs than oak for example. Wood also has a higher possibility of harbouring mould than less porous materials. To prevent mould you should make sure your wood has been kiln-dried and kept dry until you have a roof on it. Wood may also contain anti-sapstain chemicals which could explain why some people react to wood used in building and not wood in the forest. 

There are plenty of acceptable options for finishing wood. I used Hemp Oil on my floors. AFM is another great non-toxic finish. More about wood sealers in my post on sealers.

Most people should be fine with softwood plywood which rapidly offgasses. For subfloor adhesive AFM Almighty Adhesive is super tolerable. Another option is Liquid Nails Subfloor Adhesive it is less than 20g/l (lower than AFM Almighty Adhesive, but I find AFM more tolerable).

Polished Concrete

If polished concrete flooring makes you think IKEA warehouse, think again, polished concrete can look beautiful.

The Retroplate system is completely non-toxic/VOC-free but is not as cheap as I had hoped. It is available across Canada and the US, you just have to find someone who specializes in that system.

You can do acid stains, add natural pigments, use white cement, or add white sand to Portland Cement to get the look in this gorgeous photo.


Glass tiles are inert and super-MCS friendly.

Marble is good in theory but most of it has a resin put on it at the factory to fill in tiny holes and fissures, and it might have a (chemical) sealant on it as well. Though a pure slab, or tile, can be sealed with Tung Oil. (Tung oil has a smell and might not be tolerable) or AFM Mexeseal.

Slate is also good in theory, as long as it doesn't have a chemical sealer on it. Seal with 
AFM Mexeseal.

Concrete tiles are my preference because of the beautiful designs. Look for Eco tiles or ask what additives are in the concrete. I sealed mine with AFM Safecoat Penetrating Water Stop.

Porcelain and ceramic are safe if lead-free and do not contain radioactive substances.

Imported glazed tiles should be tested for lead and radioactivity. A client just tested American made tiles that stated they were lead-free, but when tested they showed high levels of lead. So it might be wise to test any glazed tile regardless of origin. And be extra careful when removing them as the lead dust is particularly harmful. Tile over if possible instead of removing.

Natural Carpet 

For natural, non-toxic carpet look for chemical-free fibers (normally wool), no flame retardants, no mothproofing, no stain repellant, natural padding and either no adhesive or a non-toxic adhesive. I have reservations about natural latex and would not use that product in my house because of how mould-prone it is.

Nature's Carpet is made with wool, no mothproofing, natural latex, natural dyes and a non-toxic padding. Either tack down the carpet or use a non-toxic glue. 

Other good companies are Earthweave (wool), Natural Home Products (wool) and Hibernia. I have sniffed Hibernia and it does have a wooly smell (as you would expect) but not a chemical smell in my opinion. 

If you have conventional carpet in your house seal in the VOCs with Carpet Seal.

Commercial grade carpet is a lot harder to find in low VOC. I have reviewed and sniffed a few of the ones that claim the lowest VOC levels. I could not find any that were 0 VOC.

Flor: Most of their carpets are commercial grade. They claim they have the lowest VOC levels in the industry as of 2017 though when probed for information on their VOC levels or any evidence to substantiate that claim they did not have any. They have Green Lable Plus which you can find almost anywhere now and is in no way a low level of VOC. However, when testing their carpet it did not have that tell-tale new carpet smell. The initial smell was as strong as other regular brands but it seemed less offensive (I know everyone is different here though.) But what did impress me was that the sample offgassed way faster than other brands that have the tell-tale new carpet smell.  A few weeks outside and it is extremely tolerable for a conventional carpet. I was in the end impressed. 

The other good option for commercial grade is wool. Though companies are more reluctant to use wool because it is more expensive. The Godfrey Hirst wool commercial carpets can show test results of very low VOC levels. Though they do have that classic carpet smell still. 

Woolshire wool is also rated for commercial, I found it much more tolerable than Godfrey, it smells wooly but not like chemicals that I can pick up. It does have moth proofing in it. It smells similar to Hibernia brand. 

So if I was picking a commercial brand I would consider Woolshire first and then Flor. 

Earthen Floors

Earthen floors are used in cob, straw bale, and other natural homes.

I love, love, these dark chocolate floors which for sure have some pigment added and are finished with walnut oil. The go-to oil for earthen floors is usually linseed oil cut with citrus solvent (all natural) but it is very smelly (terpenes!) and often intolerable to the chemically sensitive. Some have claimed that walnut oil goes rancid on earthen floors. Hemp oil could be tried on earthen floors. 

Also good to know - organic, mould-free straw should be used in earthen floors. This type of flooring goes really well with radiant heating because it keeps the floors dry and it heats the mass of the house which is way more efficient that heating the air.

If you are opting for earthen floors make sure you use a radon barrier. See Prescriptions for a Healthy House for more info on that.

2. Good for Most Sensitive People

Pre-finished Hardwood - Usually finished with aluminum-oxide-infused polyurethane and cured under UV lights, these are usually very well tolerated once cured. I consider this to be safe product for the chemically sensitive. Test it first. 

Terrazzo - Terrazzo is a little complex as there are different materials, resins and sealers involved. But there are systems that are 0 VOC and low VOC. 

Natural linoleum - has naturally occurring VOCs from linseed oil. This is a natural smell and may be tolerable for some. This is something I would consider in a healthy home if the client has sniff tested it. I tested this and found the smell mild even though I do not do well with linseed. In a small space it would certainly be a noticeable smell to anyone sensitive. 

Fiberglass Floors - Tarkett FiberFloor is a flooring made of fiberglass, foam and coatings. It may have a mildewcide in it. It is extremely low-VOC at 10μg/m3. This would be tolerable for most people. 

3. May Work for Those Less Sensitive 

Engineered Woods - Junkers, Kahrs, and Wood Flooring International all meet EU emission standards. The substrates can still be problematic. There are some engineered woods that are formaldehyde free (Kahrs) or use only phenol formaldehyde which offgasses quickly (Cali Bamboo). 

Cork, like wood, has a natural odour (terpenes). A resin is used to bind all the small pieces of cork together into flat pieces (I have seen polyurethane binders). In theory you can make tiles or rolls without resin (they heat press them) but this is not how cork flooring is made. An adhesive is required either to glue it down (and there are 0 VOC glues for this) or in the floating floors it is usually glued to a fiberboard or substrate which tends to be problematic. It is finished with urethanes/acrylic which may be tolerable once cured. I have tested Cali Bamboo cork which I found to be the best one. US Floors was the second best. NOVA and Cancork smelled very strong to me. 

Bamboo requires resin or adhesives and a finish. However, there are many that are GreenGuard certified for low emissions. This wood is problematic and is known to shrink. I put it in the same category as laminate and engineered. Not good usually good enough for the chemically sensitive. 

Laminate does give off chemicals, but there are some low-VOC options. You might want to check out the brands that have GreenGuard certification. It doesn't require adhesive which is a bonus. Generally this is not low-VOC enough for a healthy home. I have seen better options in the engineered category. 

Hard Vinyl - the kind usually seen in schools and commercial buildings tends to be well tolerated. It would be an unusual choice for a home. 

Toxic! soft vinyl, conventional carpet and conventional linoleum all give off major VOCs.

Disclosure: Some of the links to products and supplies on this page go through my affiliate partners. This post uses Amazon Affiliate links. Whether a product has an affiliate program or not does not influence my choice of recommendations. Buying through these links helps support this blog and does not affect the price for the consumer. 

Building a Mould-Free Tiny House

Building a Mould-Free Tiny House 

This article will discuss preventing mould in tiny homes that are custom built. Usually on wheels, but much of this could apply to lane houses and other tiny homes not on wheels (though I don't discuss foundations here). This will apply to some prefab but not all types.

Major problems with tiny houses that cause mould:
Re-doing my insulation
  • Very few people hire an architect, engineer or other building science expert to design the system.
  • Many tiny home companies are new and the builders lack experience or are not experienced enough in all aspects of building (from plumbing to roofing, to installing heat pumps, to insulation, and moisture management).
  • The DIY movement is a problem because the size of the home makes it seem like you can do it yourself, yet you still need all the knowledge of all the  contractors: electricians, plumbers, roofers, architects etc. to build a house. The size of it does not necessarily make it simple!
  • DIYers ofter learn from other DIYers via the internet, copying others' mistakes.
  • The movement is new and it can take 10 years for some mould problems to show up.
  • Most tiny homes do not need to follow building codes. Almost anything goes in most places, resulting in poor building practices.
  • Homes are built in one climate and shipped around the US and Canada to other climate zones where the moisture management system may not fulfil its function. Owners may also move the house to a different climate zone. 
  • Only one year warranty on many houses will not be long enough to cover mould issues. 
  • Many tiny homes I have seen have simply invented wall systems that would never be used in a regular house. 
  • I have seen major problems with the moisture management systems such as vapour barrier errors, and smaller but still problematic practices like lofts built with mattresses right on the floor with no ventilation, and inadequate exhaust fans.
  • Lack of attention to detail that comes from inexperienced builders or those not concerned about mould.
  • Building by prioritising non-toxic materials over building the correct moisture management system (because you remove or replace a part of the system with something non-traditional).

Water on ceiling due to improper vapour barrier
When I first set out to build my tiny house I was mostly concerned with choosing healthy materials that were 0-VOC. It was only after I took the house apart (almost completely) to fix the problems my builder made, that I realised the extent of knowledge needed to build a mould-free home. I thought you just leave the construction details up to the contractor, but my builder made almost every mistake in the book.

From interviewing and working with dozens of contractors in my area, I have found one out of a few dozen who was knowledgeable and detailed enough to renovate the house in the correct way.

The two most important aspects of designing a mould-free tiny house are:
  1. Have an architect (or other building science expert) who specialises in mould prevention design the moisture management system. This is everything from the wall system to the roof, the floor, and the ventilation. They will also need to take into consideration which materials you can and can’t use to design the system. Take the time to do this in detail before you hire your tiny home builder. I can also help with consulting on materials at this stage because the architect needs to know which materials can and cannot be used/tolerated.
  2. Extremely detailed supervision. I have fixed everything from my bathroom fan to my walls and roof. Taking my attention away from the project for more than an hour led to mistakes by the contractors who simply do not care about mould prevention. Even if you find a good owner, that person leaves the work to his labourers or subcontractors who are not well supervised. Here you can either hire someone extremely competent to supervise, or you can supervise yourself. If you supervise yourself, take the guidance from your architect, and learn the basics in order to follow those guidelines (or you will be calling him or her every few hours). Make sure the builders have a very detailed plan of how you want things done so that when you come into supervise you are staying on plan. There may be a clash of egos here, but you need your house done right and most contractors do not have the right skills. 
Of course choosing the right expert to guide you is also important, so before you do that you should be aware of a few different ways to manage mould that are popular and get a few opinions before you decide on hiring someone.

Here are a few different systems:
  • Passive house design - Passive house design is a very detailed system that uses a lot of calculations to manage the moisture in a scientific way. You can check out 475 to learn more about this. 
  • Breathing walls - Check out George Swanson who uses breathing walls and look up the science behind not using vapour barriers. 
  • Walls with vapour barriers - Learn the basics on vapour barriers and what smart vapour barrier are. 
  • Wood frame houses versus metal framed houses.
  • Building with SIPs.
Here are a few terms and ideas to learn about so you can follow along with your expert:
  • Flashing of windows and doors - the instructions on this are fairly simple and yet they are often not followed precisely (they need to be!) 
  • Taping housewrap - there is a controversy about whether to tape the horizontal seams
  • Rainscreens
  • Solar vapour drive 
  • Vapour barriers and condensation
  • Insulation types and their permeability 
  • Perm rating of a material/barrier
  • Air barriers versus vapour barriers
  • Ventilation - proper exhaust fans, ERVs, HRVs, and dehumidifiers
  • Exterior foam insulation method
  • Steel frames versus wood frames
  • Zip systems instead of housewrap
Do not attempt to become an expert on these topics from reading about them online. There is not enough information online to become an expert in these topics. You simply want to be informed so you can choose a good architect and understand the system they are designing for you. You may also need to learn enough to supervise the build.

Some basic mistakes you can avoid to keep your house as mould-free as possible:

Slats in my loft were a very good idea
  • Window and door flashing not done in a detailed way. Also beware of 0-VOC peel and stick window flashing which doesn’t fit most codes and is not recommend by the companies themselves for the rough openings. I have also seen windows flashed with housewrap tape and not proper peel and stick flashing.
  • Silicone and other caulks skipped where needed on the exterior due to chemical sensitivities.
  • Having air leaks into the wall cavity.
  • Housewrap not applied to spec -  including the overlap and how it is taped.
  • Roof not vented properly (there is some debate here between passive house design and most builders) or double vapour barrier issues in the roof.
  • Putting the vapour barrier on the wrong side.
  • Planning the house to be used with heating but not planning for AC.
  • Exhaust fans over the stove that don’t vent to the outside. Exhaust fans in the bathroom that could leak moist air into the ceiling. The fan I used is pictured (doesn't leak moist air).
Proper exhaust fan. Click pic for link.

  • Not having a professional plumber install your plumbing system. Or reusing old plumbing pieces that could fail on you. 
  • Pipes not designed and winterized for the climate causing them to freeze and burst. Not providing the cold and hot water a low point to drain outside. If the power goes out you will need to drain them. You may also want to drain them if you are away. 
  • Inventing a new wall system that is not normally used. Make sure you understand your wall system and which direction it dries to. Don’t skip on things like rainscreens (if that is the system you are using) just because it is a tiny house. 
  • Using wood that doesn't hold up well to humidity in the framing.
  • Putting your mattress directly on a solid surface with no ventilation under it (use slats or a box spring).
  • Using natural latex. See my warning here
  • Not using a properly sized drainage line on a heatpump. Know how to flush it out, this tends to get clogged with mould.

  • Making your regular Amazon purchases through this banner helps support me and my blog. The link to the fan is an Amazon Affiliate link and also the fan that I used in my tiny house.

    Mould Testing Overview - Pros and Cons of Different Methods

    First I want to talk about the most reliable test which is how you feel in the house compared to other places. Unfortunately this is not always as simple as it sounds to execute. There are different ways to undertake this experiment. The simplest way is to stay in your backyard in a tent or all metal trailer without bringing any possessions from the house. The most obvious complication here is that you will need to go inside to use the washroom unless you get a porta potty! You may also be so sensitive that the house has contaminated the air outside (I have experienced being outside of a house and being able to smell the mould).

    The next option would be to stay somewhere where other people recovering from mould illness (and MCS) have felt better. This could be a campground, KOA cabin, Airbnb or other rental. I have a lot more details on this in my post on the Locations Effect and Mould Sabbatical.

    Once you have gotten "clear" and done some recovering you might be wondering how do you test a house to find out if it's good? Some people can walk into a house and know if it's good for them. But even the most sensitive people usually need to request to spend 3 nights trialling the house. This is not always an option, but you should ask. Usually people sleep better in a house that is mould free, but me and other CIRS patients have found that there is some mould that puts you into a zombie sleep where you sleep more (and then get sicker). So even a three-night test can be tricky.

    It is also good to verify the house is safe with mould testing. The most common test for CIRS (mould patients) is the ERMI. It is highly recommended by Shoemaker certified doctors as the test to use. The range of the ERMI scores goes from minus 10 to positive 20. You need a score or 2 or lower to be treated and recover from mould illness according to Dr. Shoemaker.

    Other types of mould tests can also be useful. A tape lift will get you definitive results on visible mould. I look at the options below. This is a very simple overview just to give you the general idea of what is out there in a way that is not overwhelming - you may want to look more into each of these different methods. Please note that my sources were biased towards mould advocates Lisa Petrison from Paradigm Change, Greg Muske from Biotoxin Journey, Dr. Shoemaker and Cheryl Ciecko, an architect who specialises in mould. I have attempted to cross-check their information. However, going with information from the companies that do house inspections can be biased and contradictory. (All sources at end of post, which you can read for more detail).



    - Doesn’t work well in brand new houses.

    - You need dust that has settled for a while (wait 4-6 weeks to re-test an area).

    - Having very little dust or a high amount of dust can skew results.

    - Having a high amount of outside dirt inside can skew results. Having high or low outdoor spores counts can skew results.

    - May not be an even distribution of spores throughout the house if mould is only coming from one place and the house is large.

    - It is known to miss major mould problems when people are very sick in their house. Similarly, after a remediation, a CIRS patient can still be sick from the mycotoxins left behind despite a low score.


    -"Only the ERMI and HERTSMI have been associated with sequential activation of innate immune responses, not air testing.” Dr. Shoemaker. Meaning it is the only test that he found that is consistently in line with lab results for CIRS, despite its drawbacks.

    - Vacuum method can pick of heavy spores like Stachy and the Swifer method can also be used to pick up places with accumulated dust that has been there for 4 months. John Banta always tries to use the vacuum method over swipe method.

    - It's pretty affordable at $300. You do it yourself. The lab recommended is Mycometrics.


    -Similar to ERMI but tests for a handful of moulds most commonly associated with water damaged buildings. It is cheaper than ERMI. I would go for the full ERMI and you can still calculate your HERTSMI value from that. Shoemaker certified doctors will consider your HERTSMI score as well as ERMI score.

    Tape Lifts


    - You need to have visible mould.

    - It assists you with what type of mould it is and not how widespread the problem is.


    - Tells you what kind of mould you have when you have a visible sample.

    - Allows you to know if this is a toxic mould.

    - You can do it yourself.

    - It's the cheaper way to test for visible mould.

    I used this DIY Tape Lift to test a few areas in a house I go into often. The results came back showing me what type of mould it was. It confirmed that the mould was one that is toxic that comes from water damage. Though you need to get a decent amount of mould on the tape otherwise your results will just show scattered pieces.

    Spore Traps (Air Test)


    - Needs to be taken near the source, so you have to know where the source is.

    - Shoemaker says: "The industry standard of sampling the air for spores is not an acceptable substitute for many reasons. One of the main limitations is that over 99% of the particles that carry the inflammagens from water damaged buildings are smaller than 3 microns. Spore traps can only detect particles that are larger than 3 microns and therefore, miss over 99% of the inflammagens.”

    - Spore traps identify round, intact spores. So they will not catch evidence of past problem that have left mycotoxins.

    - Can miss/underreport certain heavy species like stachy.

    - Expensive.


    - The test is more standardised than tape lifts, swabs, cultures, and mould-dogs, they claim.

    - It is the most widely used mould test.

    - You can compare inside and outside air.



    - Hard to know where to place the dish to get capture the mould if you don’t know where the mould is coming from.

    - Doesn’t get you an accurate relative reading since some mould is harder to catch and some proliferate faster in the dish than others.

    - Stachy is a slow grower compared to other moulds in the dish.


    - Can be used in multiple places to compare and for general observation.

    - Can give you more details on the exact type of mould than other tests.

    - Inexpensive.

    - John Banta does a culture of the dust used for ERMI to compare and get more details

    Here is one you can do yourself.

    Mould Dogs


    - Can only detect a handful of moulds.

    - Hard to know if they are well trained, look for good references of the company.

    - They can’t tell you if it’s high amount of mould or a trace from after a remediation.

    - The dog can only sniff in areas where they can reach.


    - They are good at finding the source if it is within their reach.

    - The dog can smell both live and dead mould.

    - You can pinpoint the area where you need to do further testing.

    VOC testing


    - There is controversy around the accuracy of this testing.

    - Not widely used.


    - Test the levels of mycotoxins and other VOCs in the air.

    Here is a company that does this kind of testing that is recommended. It goes to an AIHA accredited lab.

    Public postings by Cheryl Ciecko (Architect)
    John Banta interview
    Dr Shoemaker Q&A

    Disclosure: Some of the links to products and supplies on this page go through my affiliate partners. This post uses Amazon Affiliate links. Buying through these links helps support this blog and does not affect the price for the consumer. I was given the Tape Lift test to see if I liked and recommended it.

    Converting a Cargo Van - Chemical & Mould-Free Camper Construction

    This post will cover converting a cargo van into a camper. I will focus only on a few key areas. The key factor here is insulating in a way that will not go mouldy - as metal walls are the trickiest thing to insulate because of the condensation factor. I will also look at MCS safe materials for the interior, and a few appliances that are recommended by others. 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. 

    This will also be a review of the technical aspects of Camp Like a Girl and The Vanual

    Insulating a Cargo Van 

    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. With exterior metal walls, as soon as you are heating the van to the point where the exterior wall will be dewpoint, you have a serious risk of condensation and mould in the walls. So again, to keep it simple, no water can enter the walls if you plan to heat your camper when it's cold. 

    Rigid Foam

    The Vanual
    In Camp Like a Girl, 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 used canned spray foam to fill in the gaps if that is tolerable for you. 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.

    If you are putting the plastic covers back on the walls like Camp Like a Girl, I would silicone/caulk around those to make it airtight. The most tolerable caulking is Eco-bond.

    Robert Lawson, another van owner, is trying this strategy to fill in all the gaps: he says: "I have 1-inch polyiso foam on the walls and ceilings. I plan to put Reflectix between the foam sheathing and the steel body so there will not be an air space where condensation could form. I will put another layer of Reflectix on top of the sheathing as well in order to cover all the irregularly shaped frame members."

    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. 

    Camp Like a Girl also uses insulation in the bed platform to keep the bed warm. I would be a little concerned here with flame retardants in the foam. If your bed is raised you could use cork insulation from Thermacork below you, but I would prefer to use slats under a regular bed. More on protecting beds from moisture in the last section.

    Spray Foam

    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.

    The best spray foams are Heatlock Soy line at Demilic (GreenGuard Gold certified) and Icynene Proseal (GreenGuard Gold certified) (closed cell). Both are polyurethane foams, from reputable companies that are usually easy to source. 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. 

    If you are mould sensitive but not chemically sensitive you could consider this in a van. 

    Walls and Ceiling

    Metal is your safest bet unless you are putting the plastic covers back on. This all depends on what kind of van it is, as they are all different. For an extra layer of protection, caulk around the seams to prevent moisture from going in the walls. 

    Sara used PVC ceiling tiles which are toxic, 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, but 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 formaldehyde-free plywood with strips of wood over it to get the look in The Vanual. 

    Marmoleum floors

    I wouldn't feel comfortable using 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. Or else spray foam between the joists and then use metal flooring.

    Different flooring materials could be considered - metal, which could be painted with different designs for a pretty effect, or covered with rugs, or Marmoleum which is very tolerable. You could also cover it with EVA mats. You could use wood if you are sure you have enough insulation underneath to prevent condensation from forming under the wood (and the wood can withstand high humidity). MgO board could be used as subflooring here if you are using Marmoleum or wood. The MgO will crack though.

    Interior Structures: Bed, Cabinets

    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. It also doesn't let the mattress breath. Mattresses are very susceptible to becoming damp in campers. 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). 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). I would use a sleeping bag instead of regular bedding because it can handle high humidity better. This one offgassed well with some time in the sun and is super warm. 

    For cabinets, if you do use hardwood plywood, go for a formaldehyde-free plywood like Purebond or use solid wood.


    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 Fan-tastic.


    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 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. When I camp in a tent I use an electric blanket and it provides a lot of warmth. The best kinds are the large ones with the 10 hour shut of time to keep you warm all night. You may not need a space heater if it's not too cold where you are.

    For off the grid heaters I would go with the rooftop propane heater/AC combo that many trailers have. Though extreme mould avoiders have said these can get mouldy.

    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.

    An Overview of the Process

    I like this YouTube video because it gives a good overview of the whole process and how complex it is. With a few tweaks this van could also be very suitable for a chemical or mould sensitive person.

    If the insulation is sealed up perfectly by the Reflectix and tape, then no vapour will pass through. If you have a high enough R-value to keep the wood walls from getting condensation then this could work. (You would still want to use a wood that holds up well to high moisture areas).

    A few materials need to be tweaked: use solid wood - no laminate or plywood, natural bedding and cushions, slats under the bed for airflow (which I think he did), gas stove may or may not be tolerable, a better extraction fan, and I would look for an alternative to that vehicle carpet.

    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).

    Disclosure: Some of the links to products and supplies on this page go through my affiliate partners. This post uses Amazon Affiliate links. Whether a product has an affiliate program or not does not influence my choice of recommendations. Buying through these links helps support this blog without affecting the price for the consumer.