I am about to update my walk-in shower which has an electric shower, single sliding door and tiled walls with white grouting. I have never been happy by how frequently the grouting turns black and mouldy despite using anti mould silicone.

I had considered using a wall board system but I think I still prefer wall tiles.

Whilst thinking about the job it occurred to me I could use much larger tiles than the current 8" x 6" ones and this would result in less grout shown. However, in showrooms, I have also seen some large shower tiles with dark grey grout or maybe adhesive such as that used with floor tiles with the adhesive being the grout also. I wondered whether this would be a better option for both minimising mould and to show less discolouration? Or are there better solutions to the problem of mould?

  • If mold returns quickly, it's most likely inside the wall and growing out. To really fix that problem, you'd need to gut the wall, which if you're thinking of replacing the tile, is not that difficult of a project.
    – BMitch
    Commented Jan 9, 2014 at 16:40
  • 3
    @BMitch - I agree if it is a large amount of mold that comes back almost immediately. However having demo'ed quite a few showers that were moldy - I am usually surprised how nice the walls still are. Actually the most consistent thing is - how long did it take for mold to appear in the shower? If the shower is 15 years old you probably just need to regrout/recaulk. If it is 6 months - 3 years then I would put money that water is getting to the wall. Even if it does get to wall - if it dries out completely - no mold.
    – DMoore
    Commented Jan 9, 2014 at 17:19
  • Thank you for the answers. The shower cubicle is quite old as I have previously replace the electric shower. I do use an automatic xpel air fan. I tried to bleach the mould out and use other solutions but it still is quite badly discoloured. I guess I was wondering if anyone had used grey / dark floor tile cement / adhesive for tiles and did it work?
    – Ray
    Commented Jan 10, 2014 at 15:31

1 Answer 1


So you have a couple of options that will minimize the mold right away:

  1. Wall boards.
  2. Large stone sheets - I have put up a few granite systems and they are not getting any mold.
  3. Larger tile.

If you choose wall boards or large stone sheets then you still need to caulk. There are caulks - not usually sold at the big box - that are virtually mold proof. If you want something from a big box then go with GE Silicone II. I have used it in my own house and never any mold.

The key to a moldless shower is that you only let water stand/sit in the pan. So you need to plan on your transitions and things like soap dishes. If you have a nook that is built in the wall and you see mold over it - the problem is the nook not the area directly over it.

Also I have people show me their showers and it is newly caulked... But their tiles are so old and have been scrubbed (probably with the wrong type of sponges) that they have no facing. Meaning water may penetrate just a little each shower. Without enough time to fully dry - mold.

So I get people who want a mold-free shower (and tile) and I always give them the same advice. Big tiles until you hit 4 feet. After that we can go smaller or even mosaic. The less grout the less issues. Then the key is an epoxy grout. A true epoxy grout is basically a plastic after it dries. They look great, they are mold free... So why aren't they used more...

Well the first time I used an epoxy grout was on my backsplash (1 inch mosaic) in my own kitchen many years back. I wanted to test it before I did a shower. Holy cow is the epoxy grouting like 5 times the work as regular grouting. Once you mix your A and B you have about 15 mins to get the grout in and then it slowly hardens to unworkable at around 1 hour. So you must do small batches and have a helper. But man does my kitchen backsplash look good. I have done 5 full showers using epoxy and people are pretty wowed. It is certainly worth it for a shower. You will make up your install time in less than a year with less cleaning.

Note: You should not buy "ceramic" tiles for shower - nor should someone sell you these. They are more porous and will hold water after facing deteriorates - which it will faster than the same quality of porcelain.

Another note: Only have cement back in shower - no drywall of any kind. A Kerdi like system is even better but a well installed HB shower with plastic under it that flow to pan will do.

  • A thorough response and thank you so much for the advice. Now I'll have to locate some of that epoxy grout!
    – Ray
    Commented Jan 10, 2014 at 15:35
  • They sell epoxy grout at all the big boxes. Definitely watch a youtube video or two before doing it. Also I know that you have to grout a "big" shower but take the 3-4 smaller batches of grout - compared to the big container. Much easier to do epoxy in smaller batches and worth the extra cost.
    – DMoore
    Commented Jan 10, 2014 at 16:22

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