no the pebbles aren't slippery. anything with a lot of grout lines offers traction. you can do a mosaic tile of up to 4" (4" per tile) and still have enough traction. most people use 1 or 2" mosaics for shower floor. I used a 3" hex made from honed marble. it's not the least bit slippery.

any type of small mosaic, like this, will be fine.

even this is good

We have a custom cast polymer shower pan that is "non skid." I still put down a rubber mat to shower, so I would not recommend it. I wish we had gone with small tile instead.

As Beth H wrote, small tiles with grout will provide plenty of traction but I would install a grab bar anyway. When you are building the shower you need to install the appropriate blocking so the grab bar won't fall off when used in an emergency situation.

Thankyou Beth, Hazel, Helen, Sophie, Jmm1837, & Becky,

So much good advice. I think I will heed the warning about the shower pan and go for the tile or river rock. Your grab bar advice is also valuable. We have planed on having the installer add a discrete grab bar, but after reading your comment we will make sure we ask if it is installed with the "appropriate blocking" as you said which I didn't know before. Our current shower enclosure is doing exactly that, 'rotting our house from the inside'. Many years ago when the house was originally built regular drywall was installed behind the shower tile instead of the waterproof type {that was the norm in those days or so I've heard} and water has gotten behind the tile & buckled it. Hence one of the main reasons for the bathroom redo, a complete rip out. The bathroom also has outdated look and not in a good way.

artsy:

You want to compare the coefficient of friction between different wet material choices. Science, not speculation, please.

I hadn't realized the difference between grab bars and towel bars either as you can't safely use a towel bar as a grab bar.

Since you are remodeling, put in the appropriate blocking anywhere it might be used in the future even if you don't install it. You can then take a photo of it for the future so that it can be installed safely - i.e. so it doesn't come down. You can install the blocking by the toilet as well as that is another place where one might need grab bars in the future.

If you google grab bars, you can get ones that aren't institutional looking. I have oil rubbed bronze hardware so my grab bars will also be ORB.

Also think about how you want them laid out - diagonal, horizontal or vertical. The placement is determined somewhat by who is using them as well as function - i.e. diagonal is often used in public situations since it is accessible to people of varying height versus a horizontal one which is limited in functionality in terms of height. My neighbor has horizontal grab bars at her toilet because she uses her arms to help her since she has arthritic hands.

Joe is correct in terms of COF but that is not relevant if you go with smaller mosaic or river rocks because the grout prevents slipperiness. I am renting an apartment while remodeling and have what I call the bathroom of death which has 12" x 12" marble tiles on the floor AND the shower floor. The slightest bit of wet and the surface is slippery as ice - my new floors are also marble but they are basketweave Calacatta and the grout gives me plenty of traction.

ETA - And I am sure there are better solid surfaces but the stall shower I gutted had some kind of solid surface with a "bumpy" feel and it was impossible to clean with normal cleaning methods. I've talked to friends with modern grout in their showers and they haven't had issues cleaning but they've all gone with a moderate gray/platinum grout which hides a multitude of sins :-). However, I also think it no big deal to have someone professionally clean every few years - I live in a condo with marble floors in the common area and every few years we have them polished and the grout cleaned professionally and they look as good as new after 20 years of hard use.

Textured porcelaine/stone tile..mosaics

River rocks would be my death..if rounded.

Everyone's different. Check if possible not only tile info(start with it of course) but try to "try" the tile..good stores wil understand you and give you that option.Either in a store, or you'll be allowed to take a sample or two home, retuurn it later, I sprayed some water on tile, tried it with my bare foot. Obviously I wiped it very nicely afterwards))

Lots of grout helps; but is not a real solution for whoever has more problems with balance for whatever reason.

You know yourself/family..make sure that whatever you pick answers your specific needs, and if warranted-go further in your research than common reasoning suggests-smaller tiles, coefficient of friction, amount of grout, etc. (that is good reasoning for everyone)

River rock. Quartzite. Flamed grainte. Any of these would the the most textured and slip resistant. That's not to say that ceramic mosaics wouldn't work, as well, because of the number of grout joints unvolved.

If you want a solid surface shower pan that will not have the potential leak or water or mold issues of a tile floor, consider some of the good shower pans now on the market. the Kohler cast iron shower pans have anti-slip surfaces that seem even grippy to me when I touch them in the show room. I have a Transolid solid surface shower pan (meaning that it is like Corian or Swanstone and can be sanded if it ever scratches because the color goes all the way through and there is no surface gloss coating). My pan has lines cut in a 2" x 2" pattern to resemble tile and they provide extra grip to the already no-slip surface.

My shower pan is for a wheelchair accessible situation with a trench drain on the front edge, but they have this in their "regular" style pans, too. Here is one made to replace a bathtub.

60"x32" Solid Surface Left-Hand Shower Base, Sea Shore · More Info

The drain is on the left in this pan, but they provide you with a cover made of the solid surface floor, so you only see a gap around a 2 x 2 "tile" section to suggest that the drain is even there. There is a tile flange on three sides and you can use tile or Transolid wall material to make your shower walls. No grout=no mold or mildew.

I'm sorry, but ANY shower system, solid, tile, or otherwise, can leak if installed improperly. I take offense at the supposition that tile showers are prone to mold, leaks, and so forth. First grout now is ALL antimicrobial, meaning they ALL have additives in them that KILL mold and mildew. Secondly, as for leaking, the newer methods are almost fool proof. No matter WHAT method or material you use, if you get an installer that doesn't give a damn about anything but the check, you're going to have issues. So if you want to rail against anything, rail against haphazard installers!! And as for handicap accessible showers (also called curbless) I can't count the number of showers I've done in the last year like this. IN TILE.

maybe i'm the only person in the world that is this way, but i cannot tolerate standing on anything pebbly/nubby. those 'massage sandals' make me nauseated. so, for me it would be a no using your shower as a guest. you might like 'sliced' river rocks more... i wouldnt put them in my shower but i'd be comfortable showering on them.

anyway we have 2x2 tiles that match our wall tiles and they arent slippery at all.

if you do go with river rocks, just make sure that your tile guy is experienced in laying them. if not, you may end up with a grid of obvious lines between sheets -- individual pebbles have to be moved to prevent that.

Bill, I stand corrected for my sloppy wording. I AM fully aware that everything you said is true.

I find the pebble look to be a fad that will not age gracefully. Go with a 2"X2" tile as it will give plenty of traction and not go out of style.

brushed and hammered granite; and you can find big enough to make it in only 01 piece.