A Non-Toxic Bathroom

For the MCS patient, a chemical-free and mould-free bathroom is of utmost importance. I have yet to see a conventional bathroom that does not have mould growing in walls or grout after 5 years or so.

So let's dig in.

1. Walls

Source: renewable.typepad.com
 Magnesium Oxide Board

The walls of my tiny house are made of Magnesium Oxide board which works in place of drywall. Even in a cob house, I would use MgO board for the bathroom.

MgO board is a cementitious wall board ideal for those with chemical sensitivities. It is non-toxic, VOC-free, and a very impervious to mould. If you have a wood-framed wall it will be easy to attach the board to that. Good brands are Dragonboard (US, and coming to Canada soon), Mag Board (US) and Magnum Board (available in Canada!)


Ceramic and glass tiles are inert and totally safe for the chemically sensitive homeowner.

So you don't want ceramic or glass tiles, you say. OK, well then it gets more complicated:

  • Stone should be tested for radon and sealed with a non-toxic sealer
  • Slate and Marble - make sure they don't have a chemical sealer on them already, and with marble you don't want it to have a resin on it either (which is applied to most marble before it hits stores). Seal with a natural sealer as listed in Finishes. (Marble may also need a specfic grout, talk to your contractor).
  • Concrete tiles - my preference because of the beautiful designs (see left). Needs to be sealed with a non-toxic finish.
  • Imported glazed tiles should be tested for lead and radioactivity.
  • It's preferable to have something glazed/sealed in the factory but make sure if it's something other than ceramic tile that it is fully cured and won't be off-gassing.
  • Porcelain - from what I know it should be an inert suitable material, but it may not be able to be laid in Portland Cement as grout. Look into it.

Finishing MgO Board
Source: travel-files.com
You can plaster or tile over MgO walls with plaster. If not plastered, the MgO boards would need to be primed and painted. See Finishes for a list of suitable primers and paints. I used Mythic primer and paint which was tolerable.

What about concrete?

Yes good question. Retroplate concrete polishing is a non-toxic beautiful concrete finish but I don't know if it is 100% waterproof, and I could not find anyone in BC who would do it on walls.

There are other concrete sealers that in theory should seal (unfinished) concrete, so that may be an option, and actually it is very much in style right now. I could not find one that was non-toxic and waterproof.


Tadelakt is a natural waterproof finish for bathrooms including the shower area, that has been used in Moroccan bathhouses for centuries.

It is a labour intensive finish made from lime plaster and olive oil soap which together produce a chemical reaction that provides waterproofing.

There are builders and artisans who are experts in this technique in BC and their work can be seen at OUR Ecovillage.

The down side of this finish is that you may need to polish it with olive oil soap as often as every month, and like any plaster finish, cracks will likely form, needing touch ups. So, you have to be willing to do a little upkeep with this one.

For a how-to get ahold of this book: Tadelakt.

2. Reducing Chemicals and Mould

 Grout and Caulk

 For tile grout I would use Portland Cement (with no additives) mixed with sand, lime and water, as it is the best option for a chemical-free grout. In order to prevent mould in the grout (I have yet to see grout not get mouldy with time) I would use a grout sealer (see Finishes), and be sure to stay on top of maintentece and re-seal it every few years.

Don't lay tiles over toxic particle board, or mould prone green board. 

Seal well between the sink and the wall, the bathtub and floor, around the toilet (if using a toilet with water) with Silicone. I have a post about finding a tolerable silicone caulk. Be totally vigilant with sealing anywhere water could creep in and promote mould growth. 

Reducing Moisture

A fan is absolutely vital to reducing moisture and therefore mould. I would splurge on this item. It's always good to have a window too, to air things out. Another useful tip is to squeegee the walls (and floors if you have an open drain) after showering, this can make a big difference.


To keep VOCs out of the bathroom - avoid laminates, particle board cabinets, plywood, greenboard, drywall, PVC shower curtains, melamine, conventional wood stains and sealers, conventional tile sealers, grouts with latex additives, caulk (other than aquarium grade silicone), and conventional paints and primers.

3. A Chemical-Free Shower Stall

This was THE most difficult aspects of the entire build to figure out and I have a whole post devoted to the shower stall.

4. Cleaning Products

Free labels for DIY products
Now that you have gone through all the trouble to pick non-toxic materials, and taken steps to prevent mould growth, do not go adding a bunch of highly toxic airborne chemicals with conventional cleaning products, air fresheners, and beauty products!! In fact, going with natural alternatives vastly reduces the chemicals you breath in in the bathroom and can make the difference between becoming dead exhausted after showering and still having energy post-shower.

For natural, cheap, non-toxic cleaning products see: Cleaning Products

5. Toilets

I have a composting toilet in the bathroom as it is a great sustainable option and makes it easier to be semi-off-grid. This post discusses my issues with some of the smelly additives some composting toilets require...

Sources: Re|shelter and Prescriptions for a Healthy House, 3rd Edition: A Practical Guide for Architects, Builders & Homeowners


  1. The solution for not only you and the environment, but your pockets as well, can be natural household cleaners. Products that may already be in your home, or are easy to find and buy, can provide a safe, non-toxic road to cleanliness. Recently I got to interact with a carpet cleaner that claim to be the most greenest cleaner, I must say their services were really awesome. fine more at http://www.oxifresh.com/green-carpet-cleaning

    1. I would not use or recommend any cleaning product that has VOCs. I only recommend cleaning products with 0 VOCs which I outline on the page on cleaning products. Further, carpet is not recommended for people with MCS.

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  2. Have you heard of stains and concrete sealers from BRODA? If yes, what are you thoughts on them?

    1. I don't believe we should be using low-VOC products when there are chemical-free alternatives. Many low VOC or green washed products are not suitable for people with MCS and I certainly wouldn't want them in our soil or water systems either!

    2. That's pretty much what I said to the lady selling it to me, cause they are out of the mexeseal. She said it's about knowing which VOCS are bad, and even organic, natural things give off some VOCS. She assures me this line is good. I would of rather had the mexeseal, but I need it soon. Where did you purchase yours from?

    3. That's pretty much what I said to the lady selling it to me, cause they are out of the mexeseal. She said it's about knowing which VOCS are bad, and even organic, natural things give off some VOCS. She assures me this line is good. I would of rather had the mexeseal, but I need it soon. Where did you purchase yours from?

    4. It's true that some VOCs are worse than others but I don't think it matters so much if they are "natural" or synthetic chemicals. The most important thing for you is how much do they bother you and how fast do they offgass. But since it's hard to tell the long term effects/chronic illness effects I avoid chemicals everywhere I can. I haven't ordered sealer yet but I do have a whole posts on sealers with some links. I will order them online.

    5. I really love your blog. We are building a house as we speak and trying to do it as non toxic as possible. I don't have MCS, but I don't want my family breathing toxic chemicals for the rest of our lives. Right now, unfortunately Magnum board doesn't fit in our budget because this is a temporary house for now ( we are building in the back quarters of our shop, I call it our "shouse", living there for 5-10 years, then building a house.) Anyways is there a cheaper, non toxic option for the walls in a bathroom you would recommend? If we put moisture resistance drywall up, will covering it with non toxic paint seal in toxins? Any info on this will help. Thanks

    6. Hi, I have heard of DensArmor Plus and some other low toxic wall boards. Not sure of the price. One of the AFM primers on the post about Finishes will seal in most toxins but is not 100% VOC-free itself. Plaster or tiling will also mostly seal in VOCS.

    7. Thanks. Funny you mentioned the DensArmor Plus. I just found it at Lowes :) I look forward to reading the rest of your blog. Lots of great info. Your links take me to Amazon.com, and they dont wanna seem to ship to me :( In Alberta.

    8. http://www.propublica.org/article/american-made-drywall-emerges-as-potential-danger drywall may give off calcium oxide, sulfur dioxide, calcium sulfite. on the MSDS sheet for dens armour plus it states it does give off those in decomposition

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  4. What kind of bathtub did you go with? Do you know about any concerns of cast iron or acrylic leaching any chemicals?

    1. I only have a shower but it's been a challenge. I haven't decided yet. I am wary of fibreglass. For a tub cast iron would be the best option I think.

    2. Ya that's what I was thinking, some say they are painted though. I guess I gotta make sure its porcelain enamel.

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  6. Hi
    thanks so much for this great site for building non toxic homes
    I have gone thru quite a bit as well trying to source out safe products for a kitchen and bathroom renovation in my existing home, wow it's quite time consuming. I am now looking for grout and sealer for the kitchen and vanity areas. You mention Potland cement, did you mean Portland cement?? I have also seen a product called Quartzlock. The AFM grout sealer looks pretty good. I did have some problems in the past tolerated the hard seal for some furniture pieces. I hope that this is better for me.

    1. Hi Livia, I know, it's so much to research and test. Yes portland cement is what I am using on my tiles. I tested a lot of the AMF products and the grout sealer smelled totally benign to me even when wet. The penetrating waterstop is a better sealer for cement though so that's the one I will use and it is also zero voc and to me had no chemical smell at all. I was impressed because Im used to so many zero voc products taking me completely out. They have sample sizes that you can buy.

    2. Thanks!
      Now I'm trying to find a non toxic drywall that would be good for a kitchen backsplash area. I'm having a difficult time finding the magnum board as we are in BC Canada. I would like to use mosaic 12" mesh 1"x1" tile. I've ordered the AFM 3 in 1 adhesive, Mapei grout and AFM grout sealer. Now I'm wondering if I should have gotten the AFM penetrating waterstop as you've mentioned. Thank you so much for having this blog available, it has been so useful!! I read that MgO board comes from China. This is a bit worrisome with all the stories of the toxic drywall that has been coming from there. The product itself sounds really good though. Dragonboard sounds good too. We're just trying to find some of these products here in Canada.
      thanks again =)

    3. I don't think there is a totally non toxic drywall but see the comments above and check paula laports book. MgO is easy to get in BC through: http://www.pinterest.com/pin/137993176054411138/ They will send you a sample. Dragon Board is not avail in Canada.

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