A Green Non-Toxic Bathroom

Updated Spring 2019

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If you need assistance choosing the best products for your sensitivities, please contact me for a one on one consultation. 

Non-Toxic Showers

Tiles

• Ceramic tiles are good if they do not contain lead or radioactivity.
• Porcelain - is an inert suitable material but sometimes needs to be resealed
• 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 - have a sealer on them already, and marble has a resin (which is applied to most marble before it hits stores). I have not been able to pick up an offgassing odour from it but make sure it is tolerable for you. They need re-sealing so make sure there is a sealer you can tolerate.
• 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 AFM if not sealed already.

Tiles tested to be lead free: Interceramic habitat graphite, Emser tile in Bristol, American olean starting line white subway tile. 

Shower Base/Pan

I had to make a custom stainless pan for my tiny house because we did not plan the bathroom size around the ready made ones. Shower pans typically come in acrylic which would be tolerable for most people. They also come in fiberglass (it does offgas and scratches easier), cultured stone (should be tolerable), stone (sometimes with PVC under), solid surface such as Corian (minimal offgassing) and cast iron (very expensive but tolerable).

Tadelakt Showers

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.

The downside 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 upkeep with this one. I have seen mould grow it in when it was not touched up.

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

Metal Shower Stall 

I used an aluminum shower stall in my tiny house and was really happy with it. I have a whole post devoted to my shower stall. Stainless steel could also be used.

The galvanized buckets being used in tiny houses are not proving to be durable and leak proof in the long-run.

Fiberglass, Acrylic and Solid Surface Showers

Fiberglass and acrylic showers may be an option for those not super sensitive if you installed it yourself with a non-toxic adhesive such as AFM Almighty Adhesive. Sensitive people find that fiberglass takes a few weeks to a few years to offgas. Fiberglass is low end (not that durable, higher maintenance and not that attractive).

Acrylic surrounds are a step up. There are affordable options as well as high-end option such as those by Kohler. They offgas a little but not as much as fiberglass.

Corian and Swanstone surrounds have almost no offgassing themselves, however, the epoxies approved by the companies do, and I don't know of any alternative.

Non-Toxic Healthy Tubs

Cast iron tub

Tubs can be installed with mortar and not glue. Porcelanosa and acrylic can be installed with mortar.

Typical tubs are made of enameled steel which is tolerable for most people. Cast iron tubs are the tub of choice for many people. New tubs especially if made in the US, Canada and Europe should not contain lead. Some people like a tub with claws so that no leaks can go undiscovered behind the tub.

Accessories - Zero-VOC Shower Curtains and Bathmats

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

For non-toxic bath mats there are two options, natural rubber, or TPE plastic which is non-toxic and odour free but almost always contains Microban. Silicone is another non-toxic plastic it does need to offgas when it comes out of the package.

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 would use a AFM Grout Sealer , 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 or the Kerdi and Wedi boards.

Seal well between the sink and the wall, the bath tub and floor, around the toilet (if using a toilet with water) with caulk. I have a post about finding a tolerable caulk.

Tile Backing Systems 

The Kerdi shower system can be used with cement backer boards. Make sure to test out the whole system including Kerdi Fix caulking (which claims 0 VOC). Though most people do not use the Kerdi thinset. There are also waterproof boards that are tile backer boards and waterproofing in one: Kerdi Board and Wedi Panels are recommended to produce the most mould-proof shower or bath assembly. Both are XPS foam with a backing, Kerdi is faced with tri-lam facers containing paper, polyethylene, polypropylene, and interlaced polymer adhesive, Wedi is faced with fiberglass mesh (on both sides) and coated with synthetic polymer resin mortar. I would test those against your sensitivities, they are not odourless. Here are some videos of the Kerdi shower system, the Kerdi Board and the Wedi Panels.

Which Wall Boards to Use Behind Shower to Prevent Mould

Cementitious Boards

If you don't use Kerdi board or Wedi panels, the usual best practice material for behind showers is cemetitous boards. 

Cementitious boards that can be used behind the shower and other wet areas are Durock (zero-VOC) and Hardibacker (GreenGuard Gold). Those two brands are usually well tolerated and well tested. I had some problems with Durock myself and it does not seem 0 VOC to me, but behind tiles or a shower can be tolerable.

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. Some folks are using MgO behind tiles but it is not the norm and we have seen numerous problems with MgO over the years.

MgO board is a cementitious wall board that claims it is non-toxic and VOC-free, and very impervious to mould. I have some doubts about the VOC claims because a person I know sent in a sample for testing and it showed formaldehyde offgassing. And, many people react to it. I reacted strongly to the dust and I also found the board itself retained its scent for 4 years and counting.

Brands are Dragonboard (available in the US and Canada) this is an American company with their own factory in China, they claim. They mostly supply subfloor, Magnum Board (available in Canada). Jetboard. This is an American company with a U.S.-patented chemistry/process. The binder is proprietary and it contains fiberglass. Forever Board is a MgO composite which contains fiberglass and proprietary ingredients, the latest claim is that they are made in the US.

The claims on where the different brands are made is a constantly changing story.

Any company with claims of 0 VOC needs to be able to back that up with testing. Some brands are mold prone, while Magnum when I used it, definitely was not.

A rep from one of the main companies claims that other companies often buy direct from China, from different factories, meaning you might not be getting the product you expected.

Magnesium board is not longer as popular as it was, due to concerns over cracking, offgassing and lawsuits over leaching in Europe.


Finishing MgO Board

You can plaster, paint or tile over MgO. Here are some tips on using plaster and what didn't stick to MgO.

A joint compound/drywall mud that works with MgO is One Pass (0 VOC).

If 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 (only available in the UK now).

Reducing Moisture and Preventing Mould

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

Every house should have a
humidity meter

I use this Extech humidity meter in the bathroom and the rest of the house to make sure the humidity is within a safe range of around 50%.

Use the meter to check your everyday humidity levels as well as how long it takes the bathroom fan to bring back the indoor humidity level to ~50%.

Check different rooms, comparing their humidity levels, to see if one room has a higher level. This could be the sign of an unseen problem.

You can also use the humidity meter to check the outdoor humidity levels to see when the best times are to open up the house for ventilation and airflow.

Keep an inexpensive moisture meter around to test the moisture content behind walls. I use this General Tools meter. Here is a video from architect Cheryl Ciecko on how to check the shower with a moisture meter. Every tiled shower should be checked for moisture, as most showers are not detailed right.

Meters with pins work well on drywall and wood (but not bamboo), for professional purposes like measuring the moisture content of the framing before finishing the house, expensive meters are necessary. For your own investigations you can use the General Tools brand or if you want something a little more accurate, the REED brand.

Non-Toxic Cleaning Products

Now that you have gone through all the trouble to pick non-toxic materials, and taken steps to prevent mould growth, make sure your cleaning and personal care products are all safe. Going with natural cleaning products vastly reduces the chemicals you breathe in in the bathroom. These are the ones I use and recommend.

For natural beauty products I use and recommend see this post.

Organic Towels

I recommend these organic towels from Amazon (vetted by my most extremely sensitive friend), or Coyuchi towels which are made for the chemically sensitive.

Composting 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 in a tiny house. This post discusses some issues with composting toilets for the chemically sensitive. The one I recommend is Nature's Head or the bag type models.

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

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