Good point

There is a rating for slip resistance.. A rating of 4.2 is needed at minimum as I understand the rating. I am sure you are using a great contractor, but I have read so many horror stories over on the bathroom forum about marble that I would think carefully about marble, before committing to using it.

I have mosaic tile, not marble, on my bathroom and shower floor. It has a satin finish rather than gloss, so it's ok in the shower. Penny round with a similar finish would behave the same way. It isn't as safe as tile that has more of a sandy finish however. The grout does get dirty and have to be cleaned. That's not a big deal with tile, because I can use hydrogen peroxide.

Marble scratches easily, so you'll have to scrub carefully no matter what you use to clean the grout. Baking soda will clean grout, but not as easily as peroxide. I don't know if peroxide is ok for marble or not.

Hcbm we haven’t shown this to the contractor. We were just shopping at a tile store.

Look at the rating. We have penny rounds on the floor of a tiny PR that you really couldn't slip in if you tried, but I still dont think its an issue. IME large format tile is the hazard.

I agree, avoid large tiles for the floor. Take a sample home, pour water o.n it and run your foot across to see how slippery it is. I have large tile on my bathroom floor and it is very slippery. Huge mistake and it still makes me angry that no one mentioned that problem.

The large tile does not feel slippery. We can use that same tile but in 2x2 tiles in the shower. It just won’t have the wow factor.

I will look at ratings. Funny our last two bathrooms have fiberglass bottoms so I haven’t had to deal with this issue.

Moxie, use Clorox Cleaner + Bleach, in the spray bottle. I've been using it for a long time but only recently tried it on my many miles of white grout in kitchen and utility room floors. Two big dogs gets it disgusting.

For regular cleaning, spray on, let sit for a minute, scrub grout with a toothbrush or grout brush. Rinse. It literally turns my dull grout white again with hardly any elbow grease.

I would look at the Garden Web Bathroom Forum and read about marble. Many use it without issue, but it seems marble from China has issues. Also you have to be super careful about cleansers, hair dye, soaps etc.. Lastly you need an above average installer to avoid water logging of the tile.

It won't be slippery.

But marble mosaics can be tricky to install and maintain. Even if a sample passes the stain test at home, you won't know about the pieces you eventually install, unlike a kitchen slab where you can test the actual chunk that goes in.

I prefer a glorious marble mosaic on the wall where it can be appreciated and subjected to less demanding conditions.

An interior designer I know (not our guy) now recommends against any marble on a shower floor for various and sundry reasons. In the case of a marble tiled shower she has it color matched at an Atlanta fabricator to make a single unit shower floor of synthetic marble, a material that has been updated from those swirly resin and marble dust counters of old. She does that because it looks very unobtrusive, more so than choosing a complementary, non marble tile for the floor. I don’t know what she does if the shower is really huge. I am a marble bathroom survivor and hope that bathroom style moves on soon to some less dangerous, porous material.

I will be heading to another tile showroom, hopefully today.

Have you considered porcelain tiles in a marble look? We are redoing our master bathroom and are looking at large porcelain tiles for the shower walls with mosaic porcelain tiles for the shower floor and niche. The new grouts have an additive to resist staining. Happy tile shopping. We have made 3 trips to the tile store and aren’t done yet!

Oakley, in general I have no objections to clorine bleach or citric acid products, but I seldom use them on the floor of the bathroom with the mosaic tile. That's where the cats hang out because of the heated floor. Hydrogen peroxide decomposes to oxygen and water, so any residue is relatively safe. H2O2 is fast and requires almost no scrubbing. It's also cheap.

If you use epoxy grout it will never need scrubbing.