Asked on May 01, 2018

Fresh grout dissolving in shower

by Lloyd
I’ve recently regrouted some gaps between the tiles in my shower recess however in areas it hasn’t seemed to set properly and sections simply washed away the first time the shower was used. Hoping folks can shed some light on what’s gone wrong. A few details below as to what I did:

- removed all the old grout the whole way around the tiles I was regrouting with a grout saw

- cleaned and removed any moisture / dirt from the gaps between the tiles

- I used premix grout and applied with a rubber grouting tool

- I did the grouting just before going away for a few days so the area did not get exposed to water for a few days following

- after getting back there were two spots where the grout seemed to have shrunk and small holes had appeared. I’d been pretty thorough to make sure the gaps between the tiles were filled fully but I guess its possible that I hadn’t done this properly. The dried grout also seemed chalky in spots.

- on first exposure to water sections of the grout washed away immediately

- other sections have remained and seem to have set properly

Any ideas?

My guess is that there may have been some moisture under the shower floor from where there were existing gaps in the grout and this soaked back into the grout - is moisture in the grout a reason why it hasn’t set properly?


  9 answers
  • Ann Cherkas Halstead Ann Cherkas Halstead on May 01, 2018

    There is a grout sealer that must be used

  • Tinyshoes Tinyshoes on May 01, 2018

    You might also look at Lowe's or Home Depot for grout color pen that you can darken the grout a little

  • Linda Linda on May 01, 2018

    Possibly it wasnt mixed correctly or the grout type may not have been correct. There are also additives to strengthen grout. A guideline attached which also mentions sealing. Hope this helps.

  • Danay Danay on May 02, 2018

    Not sure if this is the answer or not; but i always steer clear of the premixed grout especially in shower environments .. i would recommend removing the rest of the grout and go back with a cement based sanded or un-sanded depending on the size of your joints.

    Unsanded grout should be used in joints that are less than 1/8-inch-wide. It has a smooth texture and clings well to vertical surfaces, which makes it useful for grouting ceramic wall tiles. Sanded grout should be used for flooring and wall tile joints wider than 1/8 inch because it resists shrinkage and cracking.

    The only type of premixed grout i have used in shower was urethane grout ; even though easy to use; proved to not last in the shower and very fussy when it comes to cleansers. I went back in with cement based.

    Another place that is extremely helpful is John Bridges Tile forum .. full of excellent tutorials and lots of helpful pro's :)

    Hope this helps a bit:)

  • Shelly Shelly on May 02, 2018

    You need to use 100% silicone. The average grout will wash away for some. Same thing happened to me and a had a handyman do it. Than I hired a grout specialist and that is what he told me. He redid my shower and it's great. No issues yet and it's been 6 months. Should last 3-5 years according to grout specialist.

  • Lloyd Lloyd on May 02, 2018

    Thanks all, I think I will mix my own grout and try Silicone if that doesn’t work

  • William William on May 05, 2018

    Sounds like you did everything right except for the grout. Don't use silcone. Grout is use to seal the joints. Cement based. Silicone will not last. You need to use unsanded grout. If premixed it should be polymer modified.

  • Lloyd Lloyd on May 06, 2018

    Update: I redid the grouting mixing my own grout and it appears to have taken with no issue. Moral of the story seems to be avoiding cheap premix grout.