Need advice: newly tiler shower floor soft spot [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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12-17-2016, 09:21 PM
Hi all

Had our shower retiled...took 3 showers in the new space and noticed cracking around the penny round a few inches from the drain. Fast forward to tonight I take a shower and I step near the crack and the floor gives full on soft spot.

Contractor coming next week to walk through bathroom and discuss other issues. What could be going on with the floor? Improperly mixed grout? If I press on the spot it's as if a heel shaped hole could be made.

Looking for some guidance to help see through bs from the contractor


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Tool Guy - Kg
12-17-2016, 09:38 PM
Welcome to the forum, Mainergirl. :wave:

First thought is that mastic was used to set the tile. This material has a poor reputation in areas of extreme moisture. It might be that the mastic dried after the tile was set, but has re-emulsified after a few showers have soaked the floor. But that's jumping to conclusions.

Did you see any of the steps during the building process? Or pictures, perhaps? We need to understand what materials were used under the tiles. Tell us what you know and share some pictures if you have any. You can use the paperclip icon above the reply box to attach pics, provided the pictures are less than 6Mb each.


Houston Remodeler
12-17-2016, 09:41 PM
Pictures please. Some closer, some further away. During pic of materials would really help

12-17-2016, 09:41 PM
We'd really need to know how your shower was constructed in order to help troubleshoot. Prefab pan like a schluter pan, drypack mud pan with surface applied waterproofing, or traditional pan with a liner. What kind of thinset was used. Was the proper drying time observed before use of the shower. Things like that, pics also help

12-17-2016, 10:26 PM
Ok -- here are the in process photos I have and then one of the issue after the first shower with the cracking. Now it is worse. Note that the first photo is before I had the tiler redo the floor bc of the seaming.

As for drying time--tiler finished Monday afternoon told us we could use it after 24 hours. 191305

12-17-2016, 10:28 PM
Here is the in progress


12-17-2016, 10:30 PM
Welcome, Mainergirl. Please change that permanent signature line to a first name for us to use. :)

The in-progress photos that would be helpful are those that might show what's under the tiled photo you've posted. That and any other photos that would help us understand just how your shower was constructed are what we'd really like to see if you have them.

[Edit] I see now that you're posting more photos. If you use the paper-clip icon above the Reply dialog box you should be able to attach a handful of photos in each post.

12-18-2016, 12:48 AM
Is this over concrete or a wood framed subfloor?

Houston Remodeler
12-18-2016, 02:00 AM
More importantly, since we see the orange on the walls, is there a foam shower base?

12-18-2016, 08:02 AM
hi all, to answer questions--it's over a wooden subfloor. According to he work order they used a Kerdi shower kit 48x48 pvc with stainless drain.

Thanks for the help in getting to the bottom of this.


12-18-2016, 09:46 AM
Either the foam pan is damaged, or the subfloor has given way. If you have access from underneath, you can check the subfloor. If it's good, I can't imagine it being anything but the foam. If the subfloor is damaged, then the foam has no support and is likely damaged as a result.

12-18-2016, 10:35 AM
So sorry to hear that newly shower installed and already failing , Morgan .

It looks like you would be in a place of conflict opinions -- foam problem or unsuitable coverage behind the penny tiles -- , depending of who you will talk about it . Neither of them will get you to a satisfactory conclusion , but it will be worthy , if time and resources are available , to get the manufacturer involved in the process and have them take a shot at it .

12-18-2016, 10:49 AM
Shulter doesn't expressly say it's not OK... they just say this

"There is no minimum tile format in general. However, if mosaic tiles will be used and exposed to heavy loads a mortar base is recommended."

One would think, while a few might, most lone humans don't constitute a heavy load.

12-18-2016, 02:36 PM
Hi all

Thanks again for weighing in on this issue. I texted with the contractor whose sub did the work---he thinks that the thin set did not have time to full dry before it was grouted and that is causing the issue...ill see what his solution is and I'll mention the foam damage as another possibility as well. We are looking at a redo of our tub surround as well so I have a feeling this is going to be a long winter project.

If any of you have suggestions or solutions for a tub surround and knee wall encased in 3x12 porcelain with no access to a bullnose I would be open to hearing them. Original sub tried to hand forge the bullnose after having set the tiles ( I know right) and it looks horrible. Contractor says he doesn't have access to bullnose through his vendor so we are looking for new ideas


Tool Guy - Kg
12-18-2016, 02:46 PM
Hi, Morgan

Schluter has lots of metal profiles that would fill your need. This Diadec (®-DIADEC/p/DIADEC) is just one of them. Browse the rest of their "wall" profiles (


12-20-2016, 05:58 PM
Profiles, mitre, pencil trim, or ask around and see if there is someone that can fabricate the bullnose for you.

12-21-2016, 08:27 AM
Lots of good comments. Here's my unvarnished 2 cents, which is sort of a distillation of the above:

The foam pan may (or may not) have gotten damaged (dented, dinged, kneeled on heavily, etc.) during the install, which is easy to do for those expensive, premium, cool foam Schluter pans.

The small size of those tiles wasn't the best choice over a foam pan, anyway, but over any kind of cut or ding (dropped tool will do it, too), it would soon become a problem with tiny tiles. I thought 2x2's were the minimum size to be used over foam floor pan, but these guys have proven me technically wrong...anyway.

Now that the foam pan is assumed to now be damaged (btw, I can't see these guys using mastic, since they know enough about Schluter....), what is the solution now? That's the big question. (That's where the most contractors are going to want to at least try a cheaper fix, since they don't want to deal with a damaged pan.) This is the crux of the problem. (And if I'm right about these assumptions, what solutions would you guys insist on, from an OP's point of view?) It's useful for contractors to create doubt in the customer right about now, even if they are stand-up and want to do the best for you. (It's a human nature/pride thing...and they still might be right in what they say, too...I don't mean to throw them under the bus, either.)

As for comments about him not being able to get bullnose....hmmm. That kind of says something right there. While we weren't there to hear the full conversation, that sounds like a cop-out answer from way over here to drive the job a certain way, maybe. Yes, it may be true that it's not be available for your tile selection (often the case), but customers should then be offered alternatives like the profiles mentioned above, etc. (during the decision and purchase phase is best).

Good luck. Hopefully you can arrive at a solution. If read correctly that you were thinking about redoing the walls, then I would say it's a good time to agree to amicably tear it all out (and do the floor with something else)...or do a more solid pan for tiny tiles.

One more thought. Maybe the plumbing opening in the subfloor is just too big, and not supporting the pan in that area. Just something to look out for if this thing gets replaced completely.

12-21-2016, 04:27 PM
Maybe the plumbing opening in the subfloor is just too big, and not supporting the pan in that area.

That's my guess also.

01-09-2017, 07:05 PM
Hi all

Thanks so so much for the earlier feedback. I felt much more confident dealing with the contractor. They are in the process of redoing the shower floor and I took some in progress pics. Looking for confirmation that things are going in right direction. Concerns to me (untrained) the visible line between the sheets of Kerdi paper---they just ripped up floor and first row of tiles. Is this acceptable? I also noticed that during the demo they damaged some of the Kerdi foam on the urn, visible bc there isn't paper there--should I ask them to redo? They are supposed to start again at 8 tomorrow morning so I need to know if things are ok!


01-09-2017, 07:29 PM
'Fraid I can't tell what you're showing us in some of the photos, Morgan.

If they removed the bottom row of wall tiles without damaging the Kerdi, and if they were able to remove all the thinset mortar from that portion of the Kerdi without damaging the Kerdi, what they're proposing/attempting might work. Unfortunately, if they were actually able to do that it would mean none of your wall tiles were properly installed.

For the Kerdi installation to be watertight, the overlaps must be made with clean Kerdi against clean Kerdi with a thin thinset mortar layer between them. Old, dried-on mortar, or Kerdi from which the fleece has been torn, will not form a waterproof seal.

Surely they have waited the required minimum 24 hours for their patches to cure and plan to do flood test for an absolute minimum of another 24 hours, yes?

My opinion; worth price charged.

01-09-2017, 08:00 PM
Is that foam from the pan that is visible? If you can see foam anywhere that is a bad sign....the fabric membrane is the waterproofing, and without a 2" overlap at all seams you're not sealed up. I'm with cx, I would encourage you to insist on a flood test before anymore tile gets installed.

01-09-2017, 08:14 PM
Hi CX and Ryan,

Sorry, the foam is visible along the curb of the shower--between the gaps of the Kerdi paper.

Today guy came in, ripped up the penny rounds and the bottom row of subway tile. He replaced the foam shower pan after reinforcing the subfloor which had caused the cracks. He then installed a new foam shower pan and laid the kerdi paper.

Now where before there was a seamless kerdi paper lining the floor going up the walls I see a distinct line with a gap where the newly laid kerdi paper does not line up with or overlap the older kerdi paper.

My question is this 1) should the kerdi paper overlap as in he should have removed 2 rows of tiles to accomplish this 2) should I be insisting on 24 hour resting/drying time between the laying of the kerdi paper today and the penny round tile install? They are trying to tell me that they are going to finish tomorrow because they are using quick drying grout.

Houston Remodeler
01-09-2017, 08:40 PM

Schluter requires a minimum 2 inch overlap per their installation instructions.

01-09-2017, 10:07 PM
I'm not saying that it can't be done, but it sounds like they are trying to get out of there quick. All seams must have at least 2" of overlap for the kerdi. Look at the bag of thinset they use and see what recommended dry time is before grouting. If you grout too soon it can cause issues. Also, at this point a flood test needs done especially since this is a repair.