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-   -   Grouted shower corners stay damp. Problem? (https://www.johnbridge.com/vbulletin/showthread.php?t=124427)

Mtea 01-05-2018 09:40 AM

Grouted shower corners stay damp. Problem?
I have a new mud slope tile shower and the joint between the floor and wall was grouted instead of using caulk. After use, the floor tile and grout soon dry out normally except for about an inch or two at each of the four corners. Although there is no standing water, the grout in the corners remains damp looking for a few days after and then dries out as well.

Is this normal? Should I be concerned?

Should I consider removing the grout and replacing it with matching silicone caulk?

My understanding is that ANSI standards call for caulk at the floor/wall joint but I also see that some folks on this forum use grout anyway. It would be a pain to remove the grout, but I do have an oscillating tool that would work.


Davy 01-05-2018 05:15 PM

Next time you use the shower, dry the shower floor with a towel including the corners that you're talking about. Then see if the corners are wet the next day. I'm trying to determine if the water is coming out of the wall or is left standing after you shower.

Mtea 01-05-2018 06:01 PM

We'll try that tonight.

Lazarus 01-05-2018 06:42 PM

Just a though. Inasmuch as the corners have the deepest level of floor mud, it might not be too hard to imagine that they are the areas with the highest saturation of moisture...and would therefore take the longest time to totally dry out, and therefore, the moisture would tend to linger in those areas.

If the shower is not used for a period of several days and the grout dries out and turns the proper colour, this might be the issue. :gerg:

Davy 01-05-2018 08:07 PM

The beauty of dry pack is that water easily travels thru it. I'm not talking about sand mix mixed dry, that's not dry pack. Properly mixed dry pack will let the water sink to the bottom of the mud bed and flow to the weepholes. But, it's a system and there has to be a preslope and the weepholes protected.

Mtea 01-06-2018 07:09 AM

2 Attachment(s)
Thanks all for your thoughts. Here are two photos showing the remaining damp grout about 12 hours after using the shower last night. I dried the floor completely and squeegeed the walls. Problem indicated? What to do if so?

ss3964spd 01-06-2018 07:16 AM

Where are those corners in relation to the shower head(s) and to the people using the shower Marty?

Mtea 01-06-2018 08:34 AM


For the top picture, the shower head is in the center of the wall 43" away and opposite from the left wall in the picture.

For the second photo, the shower head is 20" inches away from the corner on the right wall in the photo.

Put another way, looking into the shower, the head is on the right wall. The top photo is the left corner opposite the door and the bottom photo is the right corner opposite the door. The shower is about 43" square.

Let me know if you need more info.

ss3964spd 01-06-2018 09:12 AM

So, the floor area directly under the shower head - an area that sees the most water, dries out normally (and everywhere else) but those corners don't. Given the symptoms described Marty, it seems to me that those corners are holding water and I'd have to guess the only reason they would be is due to insufficient slope in the bed at the corners.

It might be worth a shot to replace the grout with silicone at the floor and corner joints.

Davy 01-06-2018 11:25 AM

Marty, are the walls new also or just the floor?

Mtea 01-07-2018 04:38 AM

Davy, the whole shower and bathroom is new as part of a house remodel. It had around six month's of use when we noticed this a few weeks ago.

rmckee84 01-07-2018 08:36 AM

Do you know whow the walls were constructed? Specifically how were they waterproofed? Do you have any pics of it while it was being built?

Mtea 01-07-2018 11:18 AM

Ryan, I know there is cement backerboard on the walls and a mud slope with rubber barrier, but we were not here when they tiled the walls so could not see how the backerboard was waterproofed.

Kman 01-07-2018 03:04 PM

If they set the backer board down on the liner, and the liner isn't properly sloped to the drain, the board will hold water and give you the results you're seeing now.

Do you know what backer board was used?

Mtea 01-07-2018 03:26 PM

Kevin, I don't know the brand of backerboard, but I'm guessing it's fairly generic as the drywall people put it up.

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