# Problem with grout in shower



## Yoopergirl (Apr 6, 2017)

We just converted our tub to a walk in shower. We installed a rubber shower pan, then poured cement and sloped the floor, then cement board on the walls and applied a rubber brush on sealant to walls. Used a premixed adhesive to apply the tiles then grouted with TEC power grout. Ultimate Performance Grout. Powder form - mix with water. Says never needs sealing. We grouted and once cleaned up we did not use the shower for a week. Then when we hooked up the water, we sprayed the walls, just to see how the pressure was and all the sudden we could see black stuff coming out of the walls. It was the group literally washing away? We let that dry a couple days then regrouped the areas where the grout washed out. Ran water over the tiles and grout is still falling out????? I can very easily remove the group with the corner of a putty knife. All we had to add was water. Did we are it too dry? Any suggestions are welcomed


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## MTN REMODEL LLC (Sep 11, 2010)

Not sure... Maybe Jazz will chime in....

but using a premixed adhesive surely is not good and may be why your grout has not set....

To the best of my knowledge, premixed adhesive is not compatible in wet environments (it is not cementous).... and possibly that is why your grout has not set.

If so, the solution is not simple.... I have no idea if you can scrape that off red guard/ hydroban and redo...

Hope I'm wrong.....

(Yooper... although this was not your issue, did you pour a "preslope" before using the rubber membrane on the pan.... you may have further issues.)


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## Yoopergirl (Apr 6, 2017)

We poured the cement on top of the liner. :surprise:


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## Yoopergirl (Apr 6, 2017)

so is it that the premixed adhesive is still "wet" behind the tile and causing the grout to not set? We did find that we were able to remove a tile a day after applying it. Yikes


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## MTN REMODEL LLC (Sep 11, 2010)

Yooper.... I 'm only a GC and not a tile expert, and I don't like being any bearer of bad news, but I think it is bad news.

*To the best of my limited knowledge,* I think pre-mixed adhesive needs to dry (and even if dry, is water sensative/soluable)... so I think that has impacted your grout to set-up.

Additionally, without a preslope (under your rubber membrane) any water migration to your pan will not permeate to the drain and you will likely encounter a moldy environment. 

Again/// I hope I am wrong... and wait for Jazz or other tile men to comment.

Good luck

(As further commentary, thin set (cementous) hydrates and uses water to set, I think pre-mix adhesive has to dry (evaporate moisture) to set... and a paint on impervious membrane (red guard.hydroban etc) further inhibets an adhesive from drying. Regardless, you don't want an adhesive in a wet environment (kitchen backspalshes are fine... not a shower).


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## clarenceboddick (Nov 30, 2016)

Was the backer board Durock, Hardiebacker or Wonderboard?

What sealer did you use? How much, as in just over the seams and screws or covered everything?

Did the grout dry properly in/on the bucket you mixed it in?


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## Yoopergirl (Apr 6, 2017)

It was Durock. We live in a very rural area so Red Guard was not available. We purchased the rubber sealer at Menards. I don't remember the name. We've been at this since January just working on weekends. We did the entire thing, complete walls and floor with the rubber brush on liquid. 
We didn't wash the bucket out right away and the grout was like cement. I had to break it up with a hammer and chisel. 

Thank you to everyone for their input. I will take any extra advice if someone wants to chime in.


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## Yoopergirl (Apr 6, 2017)

I just looked at the bucket of the "adhesive" we used and it is TEC brand pre-mixed mortar. Is that different from what you guys are referring to as adhesive? That sounds like a dumb question but I'm grasping that maybe what we used is okay.


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## firehawkmph (Dec 12, 2009)

Not sure about the adhesive, I've never used it. But I have used Tec's Power grout with excellent results. It sets up about like normal grout, but it is slightly more difficult to clean up. If you used water and a sponge, you may have ended up using too much water and somehow weakened the grout. When I go to clean it, I take a white scotchbrite pad dipped in water and squeezed out so it's not dripping. I clean and shape the joints with that and then wipe with a damp sponge that has been really squeezed so it's not dripping. Doesn't over work the grout and cleans up in a jiffy. 
Jazz should be along soon, I'll defer to him.
Mike Hawkins


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## Erico (Oct 24, 2016)

Yoopergirl said:


> I just looked at the bucket of the "adhesive" we used and it is TEC brand pre-mixed mortar. Is that different from what you guys are referring to as adhesive? That sounds like a dumb question but I'm grasping that maybe what we used is okay.


Per the instructions, That pre mixed is ok for shower walls but not shower floors that can have standing water and/or submerged applications.

I don't think your use on the floor is your biggest sin. The floor may hold up under light use. Is it just you and your husband or will six kids be using it every day?

It sounds to me like you didn't mix the grout properly. Did you mix it once, wait 5-10 minutes and mix again? It's important to let the grout "slake" or fully hydrate before mixing again prior to use.

I could see a too soon application of the grout causing an adherence issue. But that grout should have set up and locked color in over the week, regardless of the substrate issue. Running color seems like a mixing problem.

The fact you could remove a tile the next day may or may not be a problem - depending on how hard you had to pry. Typically I can remove a tile the next day but it will be the thinset that splits apart and should leave some combed thinset on both the wall and back of tile. 

If the tile or wall came clean, you may have an adherence coverage issue. You have to "burn in" both the wall and back of tile before you comb out the thinset. This looks a bit like "back buttering" but is done with the flat part of the trowel. Thinset likes to stick to other thinset without a problem. Sometimes it needs help sticking to board or tile. Working the thinset in with the flat side or even a taping knife is the way to go.

I like to use dough on a countertop as an example: role some dough over a countertop and it may or may not stick. Now take your thumb and press/smear a thin layer on the top. It's going to be a pain in the areas to get off.


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## Gadget65 (Oct 13, 2020)

Yoopergirl said:


> We just converted our tub to a walk in shower. We installed a rubber shower pan, then poured cement and sloped the floor, then cement board on the walls and applied a rubber brush on sealant to walls. Used a premixed adhesive to apply the tiles then grouted with TEC power grout. Ultimate Performance Grout. Powder form - mix with water. Says never needs sealing. We grouted and once cleaned up we did not use the shower for a week. Then when we hooked up the water, we sprayed the walls, just to see how the pressure was and all the sudden we could see black stuff coming out of the walls. It was the group literally washing away? We let that dry a couple days then regrouped the areas where the grout washed out. Ran water over the tiles and grout is still falling out????? I can very easily remove the group with the corner of a putty knife. All we had to add was water. Did we are it too dry? Any suggestions are





Erico said:


> Per the instructions, That pre mixed is ok for shower walls but not shower floors that can have standing water and/or submerged applications.
> 
> I don't think your use on the floor is your biggest sin. The floor may hold up under light use. Is it just you and your husband or will six kids be using it every day?
> 
> ...


Pre-mixed should never be used in showers, on floors or walls. Power Grout should be dry mixed first, then mixed with the recommended amount of water and the the proper slake time. Then when cleaning and tooling your joints limited water, too much water will compromise the integrity of the grout. 65gadget tile installer for over 30years.


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## SPS-1 (Oct 21, 2008)

I would not use a pre-mixed mortar for a wet application for reasons stated above. But if THIS is what was used, I notice in "limitations" it says not for use over waterproofing membranes. Probably, the adhesive, has no ability to "dry", with tile on one side and Red-Guard on the other side. Pre-mixed mortars "dry", while mortars that get mixed with water "cure" --- i.e a chemical reaction. And if it can "dry", it can probably re-hydrate again.


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