Which type of bathroom flooring is both non-toxic and truly waterproof? There are now tons of flooring options that describe themselves as waterproof that I don’t think are adequate for a bathroom that has a shower or bath. So let’s go through the options that would be safe in a wet room.
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Tile Type & Tile Sealers
Tiles may be stone, ceramic, or concrete.
Stone floors should be sandblasted or naturally textured (like slate tile has a natural texture) so as to not be slippery.
Keep in mind from the start the type of sealer that you will use. If you go with a white or light cool-toned tile, most sealers contain PFAS (per- and polyfluoroalkyl substances aka “forever chemicals”), especially if used as the shower floor.
Aqua Mix Sealer’s Choice Gold, or Granite Gold Sealer are two options that are based on PFAS, though they are extremely low odor and basically odorless when dry. The PFAS may not be much of a health concern if they only touch your feet but we do have to consider the upkeep and resealing and the effect on the environment.
If your stone tiles are on the floor (outside of the shower) you can use the PFAS-free and extremely low-VOC AFM Mexeseal.
(If your tiles are not on the floor, you can seal them with the 0-VOC, non-PFAS sealer SimpleCoat which is slippery on floors).
The next tier of tiles would be warm tones or darker tiles that can be sealed with The Real Milk Paint Company’s Soapstone Sealer which is walnut oil and carnauba wax. This can be used inside and outside the shower (though for wet areas like inside the shower, it requires a very long cure time).
Then there are stone tiles, just like countertop stones, that are dense enough to not need a sealer, like dark slate.
Ceramic/porcelain should be textured. Make sure that the tile is rated for floors (some are only rated for the walls). There is no offgassing from ceramic/porcelain tiles. Some do have antimicrobials in the glaze (which will be listed), and they may contain lead in the colorant/glaze.
Lead in ceramic/porcelain tiles is actually a big concern as many brand-new tiles sold in North America still have high or significant levels of lead in the glaze. It is more common in bright colors like reds and blues, but lead can be found in neutral tiles of major American brands as well. I tested 64 tiles in 2021 and 12.5% contained lead. Here are the full lead test results.
Concrete tiles are highly porous though they can be used on bathroom floors. Floor tiles can be sealed with Soapstone Sealer walnut oil sealer (though this does darken them significantly), AFM Mexeseal, Acri-Soy, or GBS Concrete Sealer.
There are also many ceramic tiles that look like concrete tiles, and these don’t need a sealer which makes them much more practical.
Grout and Thin-Set
Grout and thin-set should be concrete-based in a healthy home. With thin-set, whether you need modified or unmodified depends on your tile type and membrane type. Ethylene-vinyl acetate (EVA) is a common polymer in modified thin-set. For grout use a concrete-based, powdered grout (not premixed). This grout type is zero-VOC and usually contains EVA. EVA is safe for the majority of chemically sensitive folks. Some brands don’t contain antimicrobials, and some do (and it seems that nano-silver is the common type). See brands in the post on thin-set and grout.
The grout should remain breathable so sealers are not needed or recommended, generally. An optional sealer option that still leaves the grout vapor open is AFM Grout Sealer. Lighter-colored grout darkens with time as it gets dirty, so starting with a darker grout is a good idea.
While you can use small tiles as the shower floor, which does help with slip resistance, the pebble tiles are not the most ideal tile type for shower floors since there is a lot of grout and the grout lines are often lower than the pebbles, causing water to pool.
Under tiled flooring you should have a membrane like Schulter Ditra and behind wet areas you should have Schulter Kerdi membranes or Kerdi Board.
2. Polished Concrete
Polished concrete can work for a bathroom floor when your bathroom is on a slab. You do need to talk to the contractors about adding (or not removing) all the texture, otherwise it’s very slippery.
Safer stains and topcoats include:
- SoyCrete – this soy bio-based non-toxic concrete stain is a penetrating semi-transparent non-film-forming decorative concrete stain that integrally bonds and colors porous concrete and masonry surfaces. The company claims this product is breathable. The stain creates natural and variegated effects without the use of acid stains. (The top coat would be AcriSoy penetrating sealer or their Eco Poly).
- Acri-Soy is a bio-acrylic (an acrylic made from natural soy oils). This is a partial penetrating sealer.
- GBS Concrete Sealer – a waterborne polyester polymer and polyurethane sealer that penetrates and becomes part of the concrete.
- Earth Paint NanoTech Floor Stain/Sealer – an acrylic and polyurethane sealer. No silicones.
- More conventional topcoats used in polished concrete are often extremely low VOC and could be acceptable in a healthy home.
If your bathroom is on a slab, polished concrete or tiles are the best choices in order to allow the flooring to dry to the inside.
Marmoleum is a natural linoleum made from flax seed oil, wood flour, pine rosins, jute, limestone, and pigments with a synthetic topcoat.
Marmoleum sheet is the only form of Marmoleum that should be installed on a bathroom floor in my opinion, and it must be professionally installed. The seams should be heat welded.
You should also “flash cove” which means the Marmoleum is installed slightly up the wall, as a sort of molding, which makes the perimeter seam much less prone to water damage. Where it can’t be flash-coved, use a silicone caulk or synthetic cove molding. Cheryl Ciecko recommends waterproofing the subfloor (with a product like WEDI) and waterproofing the seam between the subfloor and the tub before installing the Marmoleum. (May 2023 Q&A Dwell Well) And we are talking here about an upper level of a house, as she does not recommend this as an ideal flooring over a slab.
The toilet should be removed for installation and be sure to caulk around the flange so that if the toilet leaks it leaks on top of the flooring and not under the flooring.
The TopShield2, a synthetic topcoat, is fairly new and is less permeable than the original TopShield, so water is less likely to soak through even if you do leave standing water. However, this is still a “breathable” material.
The warranty for Marmoleum is 30 years.
This flooring type feels warm to the touch and is not slippery so it is nice in a bathroom.
4. Bio-Based Polyurethane Resilient Flooring
Unlike vinyl sheet flooring which has a very strong off-gassing odor, bio-based polyurethane flooring has virtually no odor and no VOCs. It comes in a solid waterproof sheet flooring, just like vinyl, or glued-down planks.
The polyurethane is sourced from natural oils like castor oil plus minerals. They do not contain plasticizers (which are used in all vinyl/PVC flooring) or any other major chemicals of concern.
One residential (non-commercial) brand is Wineo, their Purline Organic Flooring is pictured.
Another similar “safer plastic” option is TPE flooring. UPO floors are made from minerals and the plastics TPE and polyolefin. Polyolefin in this case almost certainly means PE (polyethylene) and/or PP (polypropylene). They don’t use any plasticizer and there is no PVC.
5. Click Together Flooring
Luxury vinyl plank (LVP) and luxury vinyl tile (LVT) can both be waterproof flooring types if they are thick enough and have a good quality locking mechanism.
Waterproof here means the water won’t make it past the locking mechanism to below the floor.
They are extremely low in offgassing and are often used by highly sensitive folks, though they do contain the plasticizer DOTP which has some big question marks hanging over it in terms of health/safety. Vinyl is also extremely hard on the environment.
I would not use this floor in a bathroom that has a shower or bath because I have seen the planks pull apart. This is likely because there needs to be a space left between the planks and the perimeter wall, so this allows some planks to slide.
The same thing goes for the extremely low-VOC Amorim Wise click-together cork flooring.
However, any click-together water-proof flooring can work just fine in a powder room.
Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.