What to do about leaking grout

[JackM]

What (if anything) should I do about this leaking grout on my shower floor? I installed this new glass tile in 2018 as part of a complete bathroom remodel. Used Fusion grout. Now it has started leaking, and because the tiles are see-through glass, you can see the green stuff growing underneath the tiles. Sunlight shines through the tile to cause that green stuff to grow.

Short of completely replacing the shower, which is an expense I'd like to avoid, I wonder what can I do to "fix" this? I guess my options are: 1) apply a sealer and live with the view of the green stuff underneath these tiles, 2) try to replace the areas of tiles/grout that are leaking. Or 3) go full monte and replace the whole damn shower.

Thanks in advance!

[cx]

Welcome, Jack.

You say you have "leaking grout." Do you have water leaking out of the shower, or are you talking about just leaking under the glass tiles?

How was your shower receptor waterproofed?

[JackM]

I'm not aware of any problem with the waterproofing of the shower. My only complaint is the green smudges under the glass tile.

I don't know how the contractor waterproofed the shower, but it passed inspection at the time. I could ask him....

[Davy]

I would also ask him what adhesive he used to stick the tiles. Replacing the tiles would be more risky if he used a surface applied membrane. That's why Cx asked about the waterproofing method.

[jadnashua]

FWIW, cement-based grout is not waterproof even after it is sealed.

I'm not positive, but it looks like the cracks are from movement rather than shrinkage or faults in the install. Grout is often weaker than the tiles, so it shows up there first.

Are the striations in the glass, or an artifact of the installation?

[JackM]

The striations are in the glass tiles.

[JackM]

The tiles are set on thinset which is on top of a PVC membrane which is on top of sloped foam wedges manufactured by QuickdrainUSA. The shower has a linear drain.

I think I'm learning that the see-through tiles were a bad choiceh. So I think my options are:

1) Live with the green slime, which will surely grow more pervasive over time.

2) Apply sealer every 3 months to try to keep the amount of water seeping under the tiles minimal.

3) Replace all the tiles with opaque tiles

Is that about right?

[cx]

Originally Posted by Jack

...thinset which is on top of a PVC membrane which is on top of sloped foam wedges manufactured by QuickdrainUSA.

That's unlikely, jack. If you bonded your tiles directly to the waterproofing membrane you used, it wasn't PVC. Was there a second layer of a dry-pack mortar on top of the PVC liner and your tiles were bonded to that, perhaps? Or something other than a PVC material was bonded to the "foam wedges" to which your tiles were directly bonded?

You have a link to the specific Oatey system you used for your shower?

[JackM]

It was not a PVC membrane, it was a Schluter KERDI membrane that the tiles are bonded to.

I think that means that removing any of the tiles will likely destroy the membrane. Yes?

[cx]

The only way to know if you can successfully remove your tiles from the Kerdi is, unfortunately, to try it. One of the drawbacks to the direct bonded waterproofing shower systems is the inability to do repairs to the tile. With the traditional mud/liner/mud shower receptors, your could easily remove your floor tiles and replace them. And if you damaged the mortar layer under them, you could simply remove that and replace it.

You can try to remove the tiles you have. Being so small, it might work, but you'll still be left with uneven mortar on your Kerdi floor. Can you smooth that out and still make it work? Maybe. It's risky, but possible.

My opinion; worth price charged.

[JackM]

You've done a good deed today, CK. Saved me lots of trouble.

I think I'm going to apply sealer every 3 months. I'm not going to risk having to re-do my entire shower floor.

THANK YOU!

[Tool Guy - Kg]

The idea to use sealer isn't going to be productive. Modern tile/grout sealers don't work that way. Sealer temporarily holds a potentially staining liquid at the surface of an otherwise porous surface (which your Fusion grout really isn't) for a few minutes to give you time to clean it off. If you don't clean it off in a few minutes, it soaks in where it might become a permanent stain. Sealer does not hold back moisture, nor is it designed to hold back moisture. I really wish sealer was called "5 minute temporary stain blocker while you clean it up quick". Sealer is one of the most misunderstood products in the tile industry. Even many tile salespeople don't understand it.

Are all the discolored areas accompanied by a grout crack(s) in the immediate area?

[JackM]

That's helpful information, Tool Guy Kg.

The greenish areas are all within 6" of where the grout looks kinda bad. You can see it best in this picture.

[Kman]

You got any leftovers of that tile? I'd like to see how they're actually put together, so to speak.

I'm wondering exactly what the backing is, and how that green material appears to grow between the backing and the face of the tile.

[JackM]

Yes, I have some leftover tiles. As you can see, the tiles are mounted on a standard mesh. The underside of each tile appears to be painted or something. Those striations that you see from the top are coming from the underside of each tile. Some kind of bacteria or algae seems to have attacked the paint on the underside of the affected tiles.