Was shower pan done wrong?

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Posted by: from Aurora
5/29/2015 at 11:12:31 PM

I recently had a contractor in to put in a dry pack mud bed, and I have done tonnes of research, so I could sort of tell it may not have been done right, but I hoping to get some professional input.

The contractor installed a waterproof liner directly on the ply wood (flat), over the drain and up on the studs. He then put a lot of silicone on top of the liner just under where the drain clamps sits. When he screwed down the drain clamp a lot of silicone came squeezing out and this is what he wanted. I asked him if he was going to use a weep hole protector and he said it wasn't required (actually he did not seem to understand my concern). So he then put in the dry pack and sloped the pan.

The slop of the pan does seem ok. But my concern is when water seeps through the grout into the mud bed and onto the FLAT pan liner where is going to go? Some water/moisture may reach the weep holes, if they weren't all sealed with silicone and cement.

Alot of places say you are supposed to use pre-slop, pvc liner, mud bed (ensure weep holes are protected). Other places now feel pre slopes are no longer necessary especially if I use red gaurd or other water proof membranes right on top of the cement.

So question one, did my contractor do it right, or at least in a manner that will allow to be leak proof for 10 years?

Question 2, if done incorrectly can I salvage it with redgaurd, that way no water would get through to my mortor/cement bed? But are there issues to having a water proof membrane on either side of the mortar/cement bed (PVC liner on the bottom, redgaurd on top)?

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Date/Time5/30/2015 at 2:21:15 AM

Hi Blake,

I would use a "Schluter"/ Wedi or membrane similar over top of mortar bed.

I would also use same product to seal up edges of walls and joints.

It is personal preference tho.

I feel the sheet membrane has less chance for failure.


Wayne Balliet

Project Manager

Builtru Construction

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Date/Time5/30/2015 at 1:43:58 PM

Hi Blake, Wayne nailed it! Use one of the membrane type products as the top layer of protection.

Good luck with it!

Jim Kuzma

Kettleby Handyman

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Blake in Aurora
Date/Time5/30/2015 at 3:24:43 PM

Thanks for the replies. So is it salvageable? Just put a water proof membrane on top cement? But then the cement cant breath, wouldn't that be mold heaven? Or should I tear out the cement and start from scratch?

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Blake in Aurora
Date/Time5/30/2015 at 3:29:26 PM

Keeping in mind that there was no pre slope and weep holes were not protected.

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Date/Time5/30/2015 at 4:23:34 PM

Perhaps, Blake, for piece of mind, rip it out and use a "Schluter" shower base. If it's bugging you now, it'll bug you till your dead. I never use a mud bed in my showers. Never trusted them no matter how well they're built. You don't want to rip anything out in 5 years. And stick with the Schluter Kirdi for your seams. It's much more dependable.

Hope this helps.

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Shawn from Mota-Works Inc in Calgary
Date/Time5/30/2015 at 11:22:03 PM

Use dupont bulletproof sealer on the grout as an added prophylactic to prevent any water getting through the grout.

Prism grout by Custom is the preferred choice.

The other replies have covered the right way to further protect this pan using a sheet of kerdi as an added barrier.

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Date/Time6/8/2015 at 12:57:14 PM

Hi Blake.

I have to agree with Mike. You are probably going to have to start over again. I thought I saw another post where you were planning on using the Kerdi and Kerdi drain. Looks like you opted not go with it.

You are right, you are supposed to put in pre-slope before the liner is laid. This pitches any water towards the weeping holes, which hopefully aren't plugged. As for putting any kind of waterproofing such as Redgard or Kerdi on the top layer of the mud pan, I would not recommend it with a 2 stage drain. The mud pan is actually supposed to let any water pass through to the liner and then out the weep holes. Your are correct, that waterproofing the top will lead to water being trapped beneath the tile and cause problems. If you use the Kerdi system, then waterproofing the top and tying that around the drain makes sense, as the water has only one place to drain.

Hope this helps.


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