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- Ceramic tiles are good if they do not contain lead. They can also contain radioactive minerals.
- Porcelain – a type of ceramic, this does not have chemical offgassing. You may want to avoid tiles with Microban fungicide added to them. I prefer tiles that come sealed.
Lead in Ceramic tile
All ceramic/porcelain tile should be tested for lead. I tested tiles sold in America in 2021 and even tiles from large retailers tested positive for lead.
Be extra careful with dust from cutting or demolishing tiles if you have not seen XRF results on them.
Lead is not the only toxic metal in tile glaze – zinc, barium, chromium, manganese, cobalt, and nickel can be used.
Some tiles also contain nano metals in the surface coatings including silver, copper, and titanium dioxide.
Tiles made in America have a far lower chance of having lead than imported brands, but it is no guarantee. In this post I go over brands that have made a pledge to not use lead and one of these brands was also tested by me.
- 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 odor from it, the resin appears to be cured and inert, but make sure it is tolerable for you. They need re-sealing so make sure there is a sealer you can tolerate. There are two posts for stone sealers – one for natural sealers (darker stones) and one for synthetic sealers (lighter stones).
- Glass tiles are inert and totally safe for the chemically sensitive.
- Concrete tiles – I choose concrete tiles because of the beautiful designs, though porcelain tiles now come in similar looks. It needs to be sealed if they are not sealed already.
The post on flooring goes into a little more detail on tile types.
Chemical-Free Mortar, Grout and Caulk
For non-toxic thin-set and grout see my post devoted to this topic.
The post covers brands of thin-set and grout as well as tile sealers.
Be sure to seal well between the sink and the wall, the bathtub, and floor, around the toilet (if using a toilet with water) with caulk. I have a post the outlines safe caulking compounds.
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 (most brands are 0-VOC), stone (sometimes with PVC under), solid surface plastics such as Corian and Durat (minimal offgassing if any), and cast iron (very expensive but inert).
Shower Walls (Non-Tile Options)
Fiberglass, Acrylic and Solid Surface Showers
Fiberglass and acrylic showers may be an option for those who are not super sensitive if you installed it yourself with a non-toxic adhesive such as AFM Almighty Adhesive.
Sensitive folks 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 options such as those by Kohler. They offgas a little, but not as much as fiberglass. Many contain Microban.
Solid Surface – Corian and Swanstone surrounds have almost no off-gassing themselves but for each brand you need to read the installation instructions to see which glues are required. Corian is applied to the walls with silicone, and for seams or edges they have their own joint glue which is a methylacrylic that is low VOC. Swanstone can be installed only with silicone.
Stone slabs – stone can be used as slab shower walls. You will need to consider the same sealers we looked at under stone tiles. And in the shower you may need to re-seal as often as once as year. The slabs can be applied with thinset mortar or silicone but certain elements like a soapdish require a polyester knife grade adhesive so be sure to go over all elements while planning if you want to stick to more neutral adhesives.
Sintered stone – Dekton and Neolith can be used as a slab for shower walls as well, or as very large format tiles. They are installed with mortar just like tile. 100% silicone can use used in the seams and epoxy grout/adhesive on mitered edges. They recommend installing them over waterproofing membranes.
Tadelakt is a natural waterproof finish for bathrooms including the shower area, that has been used in Moroccan bathhouses for centuries.
It is a labor-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, it’s prone to cracking in my experience, and those need touch-ups as well. So, you have to be willing to do upkeep with this one. I have seen mold grow in the plaster 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.
Typical tubs are made of enameled steel which is safe and tolerable for most people.
There have been concerns about lead in the enamel glaze. It was common in the past. Some companies like Kohler have stated they do not use lead in the glaze of their tubs.
The lead would only leach when the enamel is damaged and it’s not a form that is absorbed through the skin. Though still, tubs, especially older ones can be checked for lead.
Tubs can be installed with mortar instead of glue.
Cast iron tubs are the tub of choice for many people. New cast iron tubs, especially if made in the US, Canada, and Europe should not contain lead. You should check that the company claims no lead. The same questions and concerns stand as with enameled steel.
Some people like a cast iron tub with claw feet so that no leaks can go undiscovered behind the tub.
Acrylic and Fiberglass
Just like shower surrounds, tubs can be made of acrylic or fiberglass.
For the extremely sensitive these are not usually one of the top choices due to slight offgassing in the beginning. Though with time these become acceptable.
I have heard from very sensitive folks who have done well with acrylic tubs and did not feel there was a problem with leaching or offgassing. American Standard acrylic tubs are one brand that was reported to feel like it was a healthy material. They have freestanding and alcove tubs at Home Depot and Amazon.
Veritek is a brand name of fiberglass.
Acrylic and Porcelenosa tubs can be installed with mortar.
Cast Polymer / Composites / Solid Surface
This category has quite a few different brands and materials.
Corian, Krion, and AquateX are alumina trihydrate with an acrylic binder. They claim the final material is inert.
Victoria Albert is an engineered stone – a mix of limestone and resin (probably polyester resin).
Blu Stone is engineered stone – quartz and resin. There is no gel coat on that one according to the repair instructions it sounds more like a solid homogeneous material, like a quartz countertop.
If the material has a gel coat on it you should get a sample to check for any noticeable offgassing of that coating.
It’s possible to have a bathtub made out of solid real stone. You would want to know what kind of sealer was used. They are very pricy! Porcelenosa makes a real stone tub.
Zero-VOC Shower Curtains and Bathmats
For a non-toxic shower curtain, I think EVA is the best material.
Polyester will work just fine for many people, though it’s usually coated with polyurethane (just like camping tent material). You may need to wash and air it out before use.
Those wanting to avoid plastic can use a hemp shower curtain, I like those from Rawganique. Make sure it can dry out fully between showers and that your humidity is not too high in the house. You may put it in the washing machine to help keep it clean.
If your house is relatively dry and mold-free and you don’t shower many times per day this might work out just fine for you.
Cotton and linen are more mold-prone but some very sensitive folks do use these without a liner. Take good care to dry them between uses and launder them. Replace them when necessary.
Natural rubber (which is a latex and will have some rubber odor) works well for me. I bought this OTHWAY natural rubber mat because it had a good non-slip surface on top and also stayed in place with the good suction cups. I am happy with it. It did have a natural rubber odor at first and I left it outside for a day (others might need to leave it for a few days).
TPE plastic is non-toxic and close to odor-free. They almost always contain Microban – I haven’t found one that doesn’t.
Silicone is another non-toxic plastic that will become odorless with just a little bit of time. This is less common and usually more expensive, but extremely sensitive folks will most likely do best with silicone.
I find they all do need some time to offgas after they come out of the package. Any flexible plastic needs to air out.
Water Filtration for the Bathroom
Shower Water Filter
This Culligan shower filter is NSF-certified. It contains activated granule carbon.
This Waterchef shower filter uses carbon block which is a step up. It is also NSF-certified.
While the NSF certification only addresses chlorine, we know the carbon block is especially effective at filtering out a wide range of contaminants from chemicals/VOCs to metals like lead.
I like NSF-certified filters and prefer carbon over other options.
Sprite is a Chlorgon filter material that is NSF-certified and like KDF.
Kinetic Degradation Fluxion (KDF) is a high-purity copper-zinc formulation that uses a basic chemical process known as redox (oxidation/reduction) to remove chlorine, lead, mercury, iron, and hydrogen sulfide from water supplies. The process also has a mild anti-bacterial, algaecidic, and fungicidic effect and may reduce the accumulation of lime scale (source).
This study shows that KDF with carbon does not increase the amount of copper and zinc in the water.
Many other non-certified filters contain an unknown mix of minerals.
Bath Water Filter
There are not too many bath faucet filters. The Cuzn pictured, and all the others that I see online right now use KDF filtration.
KDF is explained above.
It’s difficult to find 100% lead-free faucets for the bathroom sink, tub, and shower.
MGS an Italian company makes faucets including showerheads that they claim are 100% lead-free. But they are pricey and need to be special ordered.
Waterstone has some stainless steel options and those ones are 100% stainless.
American Standard makes bathroom faucets with the “Lead-Free” certification, which means they can contain up to 0.25% lead, but at least they have been tested.
There are more options in my post on lead-free faucets.
I have not seen a shower head with this certification yet.
Non-Toxic Medicine Cabinets
IKEA sometimes has metal options as well. Check to see if metal is the only component or if there is particleboard.
It’s not too difficult to find all-metal versions.
I recommend these organic towels from Amazon (vetted by my most extremely sensitive friend), or Coyuchi towels which are made for the chemically sensitive.
Preventing Mold in the Bathroom
Tile Backing Systems
Don’t lay tiles over particle board, or mold-prone green board. Always use a cementitious board behind tiles or the Kerdi and Wedi boards.
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 thin-set.
There are also waterproof boards that are tile backer boards/waterproofing in one: Kerdi Board and Wedi Panels are recommended to produce the most mold-proof shower or bath assembly.
Both are extruded polystyrene (XPS) foam with a backing, Kerdi is faced with tri-lam facers containing paper, polyethylene, polypropylene, and interlaced polymer adhesive. Kerdi did confirm there are no flame retardants added to the XPS foam.
Wedi is faced with fiberglass mesh (on both sides) and coated with synthetic polymer resin mortar. I would test those against your sensitivities, this one would not be odorless.
Here are the Wedi Panels (you can mention my name at The Tile Shop for 20% off).
I would consider WEDI and Schulter before a liquid applied waterproofing system. But Custom Building Products RedGard is extremely low in VOCs at under 5 g/l and Mapei AquaDefense is 0 VOC.
Wall Boards to Use Behind Shower (Prevent Mold)
If you don’t use Kerdi board or Wedi panels (mentioned in the section above), the best material for behind showers is cementitious boards.
Cementitious boards that can be used behind the shower and other wet areas are Durock (zero-VOC), Hardibacker, and Permabase. (You can mention my name at The Tile Shop for 20% off).
I noticed the offgassing of Durock myself and it does not seem zero-VOC to me, but behind tiles or a shower can be tolerable.
What chemicals are added to cement backer-board?
Cementitious backer boards are made from cement – they can contain fly ash (which can have residual toxic metals), quartz, and perlite. They can contain styrofoam. The fiberglass scrim typically contains PVC and a plasticizer (usually phthalates).
Should you use Magnesium Oxide Board Behind Showers?
The walls of my tiny house were made of Magnesium Oxide board which works in place of drywall or cement board in some cases. 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, apart from cracking – there have been false claims about VOCs, and lawsuits over the leaching of salts.
Some brands of MgO board I would consider are listed here.
Monitoring Humidity Levels and Leaks
Bathroom Exhaust Fans
A bathroom exhaust fan is absolutely vital to reducing moisture and therefore mold.
I would splurge on this item. If your fan is within a ceiling cavity like mine is, use an external mount fan like this Fantech one. Otherwise, the fan can leak moist air into the ceiling.
In some cases, it might be preferable to have an ERV (air exchange) in the bathroom. This Panasonic WhisperComfort is the most popular among builders.
It’s always good to have a window too, to air things out.
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% or lower.
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.
Check for Leaks
Keep an inexpensive moisture meter around to test the moisture content behind walls.
I use this General Tools 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, more expensive meters are necessary.
Non-Toxic Cleaning Products
Now that you have gone through all the trouble to pick non-toxic materials, and taken steps to prevent mold growth, make sure your cleaning and personal care products are 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 air fresheners suitable for the chemically sensitive, see this post.
Corinne Segura is a Building Biologist with 8 years of experience helping others create healthy homes.
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