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.
This article contains affiliate links, upon purchase I earn a commission at no extra cost to you.
1. Tiles
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.
See my book or course for sealer options.
The next tier of tiles would be warm tones or darker tiles that can be sealed with 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 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 off-gassing 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.
40% of the tiles I tested in 2024 contained 200 ppm lead or higher. See my test results here.
Concrete tiles are highly porous though they can be used on bathroom floors.
Floor tiles can be sealed with Soapstone Sealer walnut oil sealer or synthetic sealers.
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.
For grout use a concrete-based, powdered grout (not premixed).
This grout type is zero-VOC and usually contains polymers that don’t off-gas.
Some brands don’t contain antimicrobials, and some do (and it seems that nano-silver is a common type).
See my top brands in my book and course.
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.
Tile Size
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.
Waterproofing
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 are outlined in the book and course.
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 (more on that reasoning here).
3. Marmoleum
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 tips for installing this in a way that is preventative of water damage in the bathroom (or kitchen) is outlined in the book and course.
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. 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 off-gassing (a couple of brands are 0-VOC) and are often used by highly sensitive folks, though they do contain the plasticizer DOTP which seems to be safe from what we know so far but still has some 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 ultra low-VOC Wickanders Wise click-together cork flooring.
However, any click-together water-proof flooring can work just fine in a powder room.
A Better Alternative to Vinyl….
The book includes a better alternative to vinyl plank or vinyl sheet (that is 0-VOC and contains no plasticizers).
Corinne Segura is an InterNACHI-certified Healthy Homes Inspector with certifications in Building Biology, Healthier Materials and Sustainable Buildings, and more. She has 10 years of experience helping others create healthy homes. You can book a consult here.
Join the top Substack on healing from MCS and mold!
Kailey
Hi there,
Do you have any brands for the sandstone floor that you recommend for bathroom floors ? Preferably the medium color so I can use the sealer you suggested or darker so it doesn’t need any at all. Any help in this area would be awesome. I don’t even know where to begin on this for our bathroom Reno.
Thanks!
Corinne Segura, Building Biologist
for real stone I don’t have a brand list
Kitchen Remodel Vancouver
The detailed material breakdown made it easy to understand what’s safe and practical for bathrooms. Thanks for sharing!
Lily Corley
Hi Corinne,
I was able to source some of the wineo glue down planks and used it in my garage conversion studio which is on slab. we also used in a new bathroom that is on a concrete slab. I am rethinking if it will be sufficient to protect from mold as we did not use a shluter membrane on the subfloor and used the purpose xpress underlay as the glue https://purposefloor.com/purfix-xpress-underlay/
In reading through your article, it seems to suggest that the glue down planks will be sufficient. I’m wondering if we should pull it up, put down a membrayne, and use the adhesive instead of the underlay, and glue each seem.
Thanks,
Lily
Ray
Hello, thank you for the information. We are building a tiny house on wheels and are considering marmoleum sheets, which I learned about through your blog, because they are lightweight and because tiles can crack when we drive the tiny house. We are wondering about the glue – do you know of a glue that can be used with marmoleum floor that is non-toxic? It will be over a wood frame and wood subfloor, I imagine with a membrane layer
Corinne Segura, Building Biologist
I’m quite sure you have to use the glue that they offer, I mention it on the site but you will want to check it out for yourself. no membrane.
Lid
Hi,
After reading all the info, it looks like dark slate is the safest option for the shower tray/floor as it is a natural stone. Is this correct?
Does it need to be sealed once, does it need frequent re-apply, or doesn’t need sealant at all?
If needs a sealant, is The Real Milk Paint Company’s Soapstone Sealer ok? Can I find this in the UK?
We have a baby that licks the floors so I am trying to be as safe as possible. Thanks!
Corinne Segura, Building Biologist
there are lots of safe options for a shower tray or tiled floor. whether it needs a sealer or not depends on how dense the slate is, yes to using an oil sealer if you can wait the full cure time
Lid
Thank you. I am trying to find Porcelanosa and Daltile tiles in the UK as these are two brands that you mentioned before. Are they lead-free and PFAS-free? I believe you tested them and they were lead free but I can’t find anything about PFAS. Can they contain PFAS in the glazing? Baby literally licks the floor. Thank you
Corinne Segura, Building Biologist
I have lead testing results from Daltile here in both 20204 and 2021 https://corinnesegura.substack.com/p/lead-in-tiles-testing-results-xrf
I don’t have any info on PFAS yet with tiles. I do not know of any that use them but it’s possible that PFAS are in ceramic.
Jaymee
Hi Corrine,
We purchased Daltile ceramic/porcelain tiles for our bathrooms in cool light gray, off white, and warm light gray colors with matching grout by Custom. I understand that we don’t have to seal them since they’re ceramic, but if we use the AFM Grout Sealer will that prevent or at least slow down the grout from turning dark? Thank you!
Corinne Segura, Building Biologist
I’m not sure if AFM Grout Sealer will stop the color change, I doubt it but you should ask the company
char
Corrine. I would love to buy you a coffee. However my computer was scammed. Took 2 years to get it straightened out. I no longer post anything financial, not even credit card numbers. If you have a physical address where I could sent coffee money, I am ready to do so.
char
Bathroom Flooring–Hi. Not a tiny home but bathroom flooring. Builder very big and recommending/pushing click flooring throughout, including bathrooms. Have found VOC ress and recyclable.
–you would recognize the company, but unable to remember just now. I am concerned. My question is –there are materials to install below the floor. Is there one especially safe and waterproof that would insure water does not get to the underflooring? I am ok with the rest of the house.
But the bathrooms concern me after this article. I appreciate so much. A waterproof underlayment in bathrooms seems? the solution? Thank you
Corinne Segura, Building Biologist
You could put down a plastic underlyament – most of the underlayments have a plastic vapor barrier or the underlayments used under tile can go down first (Schulter) but you can still get water stuck between the planks and underlayment which is why I would not do this.
char
So grateful. Been considering Marmoleum, this solidifies my choice. Especially like the flooring up the wall as molding. Mentioned to builder he was so against, tried to make me seem totally foolish in front of others. I allowed his comments to cause me to waiver. No more. Thank you
Stefano
Hi,
I really appreciate your informative material here online.
I need a tile ‘look’ flooring for some bathrooms in my home and was considering marmoleum but I just found out about a German brand tile that’s supposed to be zer-voc by Inhaus called Sono. My home has a basement and then the main floor and an upper as well. There are bathrooms on each level. What would you recommend for my bathrooms that’s going to be waterproof, scratch-proof and zero-voc (no off gasing)?
I’m also looking at the mohawk airo carpets for our bedrooms. Do you recommend the airo or another brand (I think you mentioned a couple other brands) with the same zero-voc build as far as carpets?
I’m interested in a plush cut pile form, lighter in color tan/white tone, same for the bathrooms, as for the color tone.
I’d really appreciate a reply at your very earliest convenience.
Thank you
Corinne Segura
I mention sono eclipse in the main “non toxic flooring 2024″ article”. I also have an article and video just on carpet.
Brigid
I’m so sorry that I am asking this again, but I can’t seem to find where I posted the question the first time (you probably don’t allow searches to include comments for privacy reasons – thank you!)
I am trying to determine the best kind of baseboard for a bathroom. Should I go wood since it breathes or something else to seal in the moisture from the drywall?
Corinne Segura
solid wood baseboards should be fine. PCV if expecting a lot of water. There is also TPU coving.
Brigid
THank you!