I need some advice and experienced opinions. Here's the background, we built a new house and the contractor hired a sub to install the showers, two of them. It is a stained concrete slab floor with radiant hot water heat tubes embedded. The showers are walk-ins with slab granite walls and pebble tile floors. The sub put down the membrane on the flat concrete floor and installed the drain that clamps the membrane and has weep holes in it. He set cement board on the membrane attached to the studs and the set the granite slabs in place. Then he poured concrete to create a slope and set the pebble tile on top of that. A short time after we moved in we began to notice that the bottom 8" or so of the granite stayed dark like it was continually wet. We began to question whether anything had been sealed. After several months we noticed that the concrete floor outside the threshold was getting dark from moisture. The floor itself is sealed and doesn't change color when mopped, etc. we decided we had to dry the shower out and get it sealed so we stopped using it and set a fan in the shower. It's been five weeks and the discoloration at the bottom of the walls is still there although one area directly in front of the fan has dried some and returned to its original color. I was convinced that there was water trapped in the pan but could get no response from the contractor other than we had a humidity problem and we needed to run the A/C. The bathroom isn't closed up and we have run the A/C with no change. After five weeks of no water being run in the shower and very little in the way of drying having occurred, I was convinced that water was trapped in the pan so I drilled a 1/2" hole through the grout near the wall very carefully stopping short of the membrane. Within a few minutes the hole was filling with water and now stands with 3/4" showing. I estimate that the bottom of the hole is 3/8" above the membrane so that means there is over one inch of water standing in the pan.
The walls and floor were not sealed so too much water is getting down to the membrane, no question. But after five weeks shouldn't the accumulated water have drained away through the weep holes. I understand that since the membrane was placed on a flat floor, no pre-slope, that there will probably always be some water that can't escape but 1"+? And since the granite bottom edge is standing in this pool it is wicking up, thus the wet bottom section. The contractor is saying its all caused by it not being sealed and we were supposed to do that so it's not his problem. I'm saying sealed or not, one inch of water trapped in the pan after five weeks indicates that the weep holes were blocked up during installation and can't do the job intended. Opinions?

the membrane needs to be 'embedded' in the pitched mortar base, NOT laid under (or on top of) the 'cement board'~ cement board 'could' be used as a 'sub-base' for the pitched mortar base depending on flooring, but it would be the bottommost layer







assuming your description of installation is correct: the entire job needs to be 'chopped up' and redone

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 4 times.

Thanks for the response. I want to clarify a couple things. The cement board isn't under the floor, it's behind the slab granite on the walls. In your diagram it shows the membrane being placed on a sloped surface so any water that reaches it will drain out. In our installation the membrane was placed on a flat concrete slab and then concrete was poured on it to create the slope for the tile. The concrete board and granite were stood up on the walls inside the membrane so the edges of both of those materials are sitting on the membrane. Since the membrane pan is flat and holding an inch of water it is wicking upwards.
The other issue is that standing water. Since the pan is flat I can see that not every bit of water is going to drain out but should there ever be that much water standing in there?
Thank you for you help with this mess.

gotcha

still WAY wrong

the embedded membrane MUST be pitched

the 'wall board' and granite should NOT be on or near the membrane itself ~ to avoid puncture and wicking

? if the membrane is directly on the (sub)floor how did they get the drain to 'clamp' the membrane ?



sorry, but the ONLY fix will be a total DO OVER

? warranty ? bonding ? license ? permit ? inspection ?

best of luck

and

CAVEAT EMPTOR

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 2 times.

if the membrane runs above and into the shower drain lower section, it can not hold 1" of water.

Thank you for the responses.

Everything you have said makes sense and the diagram clearly illustrates how it should have been done. Now comes the fight over what happens to fix this. Yes, it was a licensed contractor and inspections by the county inspectors were done but not an inspection specifically of the shower installation.

The contractor is saying if the grout had been sealed there would not be a problem. It is my contention that, yes it should have been sealed, but if the installation had been done properly we would not have a problem with water wicking up into the granite. Sealer will go a long ways toward keeping water away from reaching the pan but there is always the possibility of water making its way down through, thus the need for the pan.

Concrete/grout is not a flexible waterproof material and is susceptible to tiny cracks no matter what its sealed with. With the granite sitting on the flat membrane, having no slope to the drain, even the smallest amount of water reaching the pan would sit there and would cause a problem.

Again, thank you for your help and advice.



Edited 2 times.

in the drain assembly are blocked, then the water level will rise in the pan.

there is NO fix other than:

chop it out and do it again PROPERLY

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Those pictures of the traditional liner method have a major flaw. There is no proper way to attach backerboard to a shower curb without puncturing the liner. That kind of install is the reason for about half of the shower remodels that I do.

jerco;

WRONG WRONG WRONG

there is NO ISSUE

don't nail the 'backer board' below the overflow level of the curb !!!!!!!!!

[if no curb (european style) don't nail lower 3"]

"problem" solved !!!!!!!!!

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

bernabeu......Read what he is saying. They show backerboard on the curb. There are so many ready-to-tile shower bases out there now, there's no reason to be playing around with any of that stuff anymore.By the time you pay for labor and materials to fabricate one, you can purchase a quality pre-fabricated one.

you attach the TOP piece of the curb backer with screws

you attach the vertical piece of the curb backer (inside the pan, the piece outside does not matter) with screws near the EDGE of the top piece and into the SIDE of the vertical piece - the screw never penetrates the membrane below IT'S overflow level - PLENTY OF CAULK BEHIND as reinforcement - plenty of attachment strength for a one tile row

The 'membrane system' allows a completely custom size and shape

DOH

ps. if well designed and properly pitched one would not need a curb - if installing a 'square box', of course buy prefabbed

DOH

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

Here's an update. The contractor brought out another tile guy to get his opinion. They chipped up the floor around the drain and found no pea gravel or other medium around the weep holes but found that the drain had been set so high off the floor that the weep holes were almost an inch above the membrane level as it sits on the level concrete slab. There was no water standing around the drain as I had expected to see but it was damp. So there is water trapped around the perimeter of the shower where it is wicking up into the granite. What we also discovered is that mortar was not used to pour on top of the membrane, it's concrete. They had a devil of a time breaking it up around the drain enough to see what was going on. So it would appear that the concrete is keeping the water trapped around the perimeter of the shower and even if it were able to reach the center the weep holes are so high it couldn't drain out.
Here's what they are proposing. Tear up the floor completely, pour a sloped base, use a product called hydro-mat which will take the place of the existing membrane, then lay new pebble tile and grout it with lattacrete epoxy grout. The contractor is proposing to pay for everything except the expensive epoxy grout. He says that's an upgrade and he's only willing to put back the level of materials originally installed.
I know nothing about this system. Can you advise? Thank you again for your help.

he has seen the issue and agrees the installation is improper

he is willing to fix it at his expense

he is suggesting an upgraded VERY expensive grout

if you watch and observe and check at each step you will be A-OK

(just don't get in the mechanics way or be a PITA)

imo: go for the grout as 'insurance'

best of luck

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Question the contractor, as to how the new floor membrane will be sealed to the existing membrane(the original pan membrane) that is running up the bottom of the walls. It's called a "pan" for a reason and the floor membrane needs to be fully sealed to the lower wall membrane. Make sure that there is a flood test done, before the tile is installed.



Edited 1 times.

OP:

you now know more than enough to 'bird dog' the work

it is YOUR shower

ensure it is done right and it will be right forever

BEST OF LUCK (even though you no longer need it)



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638