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.


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 Cementitious Boards

The walls of my tiny house are made of Magnesium Oxide board which works in place of drywall. It does have a problem with cracking along the seams, at least in a tiny house.

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!)

Other cementitious boards that can be used around the shower are Durock (zero-VOC) and Hardibacker (GreenGuard Gold).

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Finishing MgO Board

You can plaster, paint or tile over MgO. Here are some tips on using plaster. If not painting, the MgO boards would need to be primed. See finishes for a list of suitable primers and paints. I used Mythic primer and paint which was tolerable.

Non-Toxic Shower Stall

  • Ceramic are good if the glaze does not contain lead or radioactivity.
  • Porcelain - is an inert suitable material.
  • All 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. And be extra careful when removing them as the lead dust is particularly harmful. Tile over if possible instead of removing.
  • You may also want to avoid tiles with Microban fungicide added to them.
  • 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 specific grout, talk to your contractor).
  • Glass tiles are inert and totally safe for the chemically sensitive homeowner.
  • Concrete tiles - my preference because of the beautiful designs. Look for "eco" brands or ask which additives are used. Needs to be sealed with a non-toxic finish.
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.

Metal Shower Stall 

I used an aluminum shower stall in my tiny house and this was a difficult aspect of the build to figure out. I have a whole post devoted to my shower stall. Stainless steel could also be used.


Fiberglass may be an option for the not super sensitive if you installed it yourself with a non-toxic adhesive. More info about that in this post.


For a non-toxic shower curtain, I use this EVA one.

For non-toxic bath mats there are two options, natural rubber, which still has a rubbery smell, or TPE plastic, which is non-toxic and odour free but almost always contains Microban which I would avoid. .

Chemical-Free Mortar Grout and Caulk

For non-toxic thinsets and grouts see my post devoted to this topic.

In order to prevent mould in the grout (I have yet to see grout not get mouldy with time) I would use a AFM Grout Sealer (see finishes), and be sure to stay on top of maintenance and re-seal it every few years. The grout should be replaced when the mould is deeper than just surface.

Don't lay tiles over toxic particle board, or mould prone green board. Always use a cementitious board behind tiles.

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 caulk. My top pick is Ecobond.

Reducing Moisture

A fan is absolutely vital to reducing moisture and therefore mould. I would splurge on this item. If your fan is withing a ceiling cavity like mine is use an external mount fan like this one. Otherwise the fan will leak moist air into the ceiling. If you have a composting toilet and don't want to overrun the fan with your bath fan you can use an HRV like this one. It's always good to have a window too, to air things out.


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 toxic additives, conventional caulk, and conventional paints and primers.

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 breathe in in the bathroom.

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


I recommend these organic towels from Amazon (vetted by my most extremely sensitive friend as well (mould and chemical sensitivity)) or Coyuchi towels which are made for the chemically sensitive.


I have a composting toilet in the bathroom as it is a great sustainable option and makes it easier to be semi-off-grid in a tiny house. This post discusses some issues with composting toilets for the chemically sensitive. The one I recommend is Nature's Head.



  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.

  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

  3. 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.

  4. 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 =)

  5. Hello,
    Thank you for all your helpful information, it has guided me along the way to a healthier home. Need some advice. We are doing a partial bath renovation and need to do some retiling over hardibacker board on a shower wall. Can you give a recipe for a non-toxic grout? I can't find any that use lime. Also, the tiles lines will be very thin so I've read not to use sand in this case. Can I leave the lime out or is does it help with mold? A good mudset recipe would also be greatly appreciated. Thanks so much.

    1. The contractor should know the right proportions. the lime is optional. the sand can be very fine or crused. If using thinset you can use c-cure foormix 900, thinset 911, wallmix901 or laticrete additive free. Those are synthetic free. For vinyl additives: c-cure multicure 905, or c-cure permabond 902. For grout free of additives c-cure AR sanded grout 922, c-cure supreme grout 925, hydroment, mapei or summitville-700 summitchromes. use AFM safecoat grout sealer

  6. Thank you. I was going to use Laticrete 317 but the Laticrete rep said that Hardibacker requires a modified thinset. Is there a way around this? I really would like to avoid any toxins and harmful vocs. Thanks again.

    1. I would call Haribacker. Unmodified thinsets should be used on concrete slab, concrete board and mortar beds. Without synthetic additives the thinset is prone to cracking. That is all according to Paula-Baker Laport. Thinsets with additives that are low odour and offgas quickly are c-cure multicure 905 and c-cure permabond 902. But those both still specify over ply or concrete board.

  7. Thanks again for taking the time to address my concerns! I've found a tile guy who can lay tile with thick set mud the old fashioned way. We will see.. Thanks again!

  8. Hello. You said "Don't lay tiles over toxic particleboard or green board". To do tiles one usually has to put toxic ply underneath. Even if its toxic, the toxins will be sealed underneath the tiles and can't travel through. So why do you say not to do that? Thanks

    1. Hi, tiles should be over cement board in order to not get mouldy. Grout is vapour permeable as well so would not seal in toxins.

  9. Hi Corinne
    Do tiles typically emit high levels of VOCs if they have been treated? I am deliberating if I buy conventional tiles and just go for a VOC free adhesive and grout instead - seems a bit easier! I am based in the UK and we seem to be less eco friendly than in the US!

    1. Ceramic, porcelain and glass tiles do not emit VOCs.

  10. Hi Corinne,
    Thank you for this great website and all the work that you have put into it. I am concerned about tiles with Microban on them. I also noticed the tub mat you recommended a while ago has Microban on it. Do you have any information on Microban?
    Thank you,

    1. Thanks for noticing that Carol. I wouldn't recommend Microban. I will look for a better bathmat tomorrow and update.

  11. Hello, thanks for this article!
    I have a question - I am looking for non-toxic lead-free backsplash tile. Glass subway tile was my top pick, based on this article. However, I stumbled across another article which mentioned that lead is commonly used in glass tile? Not sure if there is any truth to this? Any insight would be greatly appreciated. I really need to pick a backsplash tile soon, and I am stressing over accidentally picking something that contains lead since I have small children. Thank you SO much!!!

    1. Hi, I don't believe glass tiles have lead but with tiles always ask the manufacturer. They don't always disclose their lead levels so if you are very concerned, your next step is to ask for a sample of the tile and test it. I also would not be super concerned as you would almost never touch backsplash tiles.

    2. Thanks so much for the reply! I really appreciate it! I think I should have mentioned that my husband will be installing the backsplash so I gues I'm concerned about lead dust generating from cutting the tiles to size and during installation, etc. I will follow your recommendation to test in advance. Maybe I'll get my husband to do a test cut and then we can test the dust generated. Thank you!

  12. Hi! I am finding your site so helpful in screening materials for our remodel. Thank you for your exhaustive work in making all you've learned public!

    I have a quick question: here in California they use asphalt to "hot mop" seal the shower floor. Do you know of any equally-effective and non-toxic alternatives? I am concerned about long-term offgassing issues from the VOCs in the asphalt.

    1. That tends to be quite regional doesn't it! I have only heard of that in CA. I would look into the Ditra system.