Kerdi Drain Problem..installed 5hrs ago [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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12-05-2009, 10:27 PM
Okay, I'm so frustrated. I've read through and searched this forum as well as a ton of online references but still can't find an answer. I've read old and new posts on DensGuard so am pretty confused.

I bought the Kerdi Shower Kit (including pan, curb, drain, Kerdi membrane, etc). I tore out my fiberglass shower stall to put in a stone shower. My dad bought me Georgia Pacfic's DensGuard as it's supposed to be a tile backer used in water areas but easier to use then cement board or hardibacker. He's not overly hip on the idea of using plain old sheet rock in a bathroom and read where GPs DensGuard is a new alternative for tile backer in showers.

I've read that the built in moisture barrier in the GP DensGuard will cause issues with the Kerdi Membrane...trapping moisture OR not allowing curing time.

1) Is it okay to use DensGuard with the Kerdi shower system?
2) If yes, what do you use to adhere it?
3) What's the cure time using DensGuard?
4) Can I use the 3/4" mosaic tumbled marble on the Schluter Kerdi prefab shower floor?

HELP!!!!!!! ~please~

What I have:
Kerdi ShowerSystem
Densguard (blue stuff from Lowe's)
12"x12" White Marble (yes, I know, Marble in a shower!)
3/4" x 3/4" Tumbled Marble on Mosaic mesh for shower floor
White Laticrete 317 unmodified thinset
DILEX-EKE for corners and where walls meet shower floor

Ditra for bathroom floor
Acrylic modifier (to mix with Laticrete to lay the Ditra to my 1-1/4" plywood floor)

Shower is 3'x3'x8' with a 12" overhang in doorway of shower..think closet in a small bathroom :) I have two vent fans: 1 in the shower stall ceiling and 1 in the center of the bathroom ceiling light.

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12-05-2009, 10:38 PM
Hi Heather.

I'd take the Densgard back and buy regular old drywall. I appreciate where his concern aobut drywall in a shower comes from, but it is what you want with Kerdi.

Can I use the 3/4" mosaic tumbled marble on the Schluter Kerdi prefab shower floor?

As far as I know there is not a minimum tile size specced for their foam pans.

12-07-2009, 08:26 AM
I literally just got off the phone with Schluter. They said...
You can use the Densguard from Georgia Pacific, just use an unmodified thinset to apply the Kerdi membrane and let it dry for 24hrs before tiling to let the layers of thinset dry in the corners and joints since there are so many layers of thinset and membrane.

So, for anyone else out there using the Dens products from GP and the Kerdi, you CAN..there is no issues regarding vapor trapping, just use unmodified thinset..even with the fiberglass facing.

I've sent an email to them as well requesting the same info, so I have it in writing.

Densguard is the Lowe's branded product from GP:

UPDATE: Here is the email from Schluter.
Hi Heather,

Thank you for your use of the Kerdi Shower System. Kerdi can be installed over Densguard with an unmodified thinset. The tile is installed over Kerdi with unmodified thinset unless it is a resin back tile then there are some special considerations. Below is a link to the Shower System Installation Handbook. You can review the installation details on page 4, 5, 12 and 13. On page 22 there is information about what thinsets to use with Kerdi. Please feel free to contact me with any other questions.

Best regards,


12-07-2009, 08:30 AM
Welcome, Heather. :)

While you've found that you can make allowances and use a different product as a backing for your Kerdi shower, I'm still wondering why you'd wanna bother doing that instead of simply using the manufacturer's recommended product.

Really I am. :scratch:

12-07-2009, 09:02 AM
Simple...I don't have a vehicle to transport sheetrock. I have to rely on others to get large items from the store to my house. I have a regular old car/sedan. So, I've had the Densguard sitting in my garage for a week trying to decide/figure out if I could use it or have to make another call to borrow a truck or get my dad to take what he brought me back to the store, buy more and then bring it to my house. He lives 50mile round trip away and is incredibly busy (has 7 kids, 15 grandkids that he totes about).

12-07-2009, 10:29 AM
Already having the Densguard and not having to return it is a sound reason to continue as you have planned Heather. :D

12-08-2009, 08:20 PM
Hi, in midst of bathroom remodel. Gutted everything. In process of construction.

Have Schluter shower kit cut down to 35-1/2 square taking inches off all 4 sides to make square and drain centered.
I used Laticrete 317 unmodified thinset under Schluter showerpan..i pulled the whole thing up twice to ensure good coverage of the pan to the subfloor.
I put the 317 over the drain "popout area"
I then cleaned, primed, and glued pvc drain in place making sure the hex shapes had thinset gooeing out of them...assuming contact was good.

5hrs later, half of the drain is solid, the other half gives up and down.

What do I do to fix it? I'm kind of stuck and hate to move forward with the Kerdi on the base if I have to...dare I something out.

I'm concerned that the fix may have been to tight and the styrofoam popped at the hinged area. The PVC is definately glued in though. I can't move it at all.

I have the curb, all corners kerdi-fied. Bu, I haven't put down the kerdi over the base yet (still working on the walls..1-1/2 walls left to go).

Houston Remodeler
12-08-2009, 08:24 PM
Do you have access from underneath? If you do you can cut the pvc pipe and use a repair coupling .....

12-08-2009, 08:55 PM
Hi Heather, what Paul said. :) If you can get underneath you might be able to wedge the pipe down some to keep the drain tight if it doesn't compromise the slope of the drain pipe.

Houston Remodeler
12-08-2009, 09:07 PM

I was thinking more along the lines of taking a small chunk out of the vertical drain pipe, say 1/4" thick to allow the flange to drop lower. My guess is the PVC pipe expanded for some reason. Wedging in the drain pipe may cause noise during use if it creaks when it gets warm from the hot water. Perhaps a rubber mission fitting to absorb any flexing of the pvc? Ideally I'd like to see a picture from underneath covering about 30 sq ft, but in the mean time we can keep spitting out ideas until something sticks to the wall.

12-08-2009, 09:22 PM
Wedging in the drain pipe may cause noise during use if it creaks when it gets warm from the hot waterGood thinking Paul. :tup1:
Cutting the riser and adding a mission couplink (fernco) is good too.

12-08-2009, 09:37 PM
I tightened the strap the plumber put in place. But that didn't work.
Tried that around 6pm :)

12-08-2009, 09:39 PM
Hi Heather, try to mix up some thinset kinna loose and cram it under the flange. :)

Houston Remodeler
12-08-2009, 09:43 PM
OK so the repair coupling idea is out.

Go with what Mike said, lift the drain a little, wedge it up, throw in the mud, pull out the wedge, light a candle, pray that works.

12-08-2009, 09:47 PM
That's copper on that drain line. Never seen that before. :eek:

12-08-2009, 09:53 PM
Heather, would you please bookmark this thread and use it for all your project questions so folks can see what you're working on and what's been previously asked and answered?

We can give it a more generic title any time you'd like. :)

12-08-2009, 10:54 PM
Like others said, mix up some thinset pretty loose...then put it in a ziploc bag and cut off one corner or use a grout bag or frosting decorating bag thing. Pry up that drain and squirt it under. You could also use some Sika rapid setting epoxy (HD, comes in a caulk tube) but it's pricy.

12-08-2009, 11:00 PM
That's copper on that drain line
I'm assuming it's an older house. The house I grew up in, which my Dad is still there has all copper drain lines. I guess that makes me kinna old. :x:

12-08-2009, 11:29 PM
Can't imagine copper lines that size. There's a gold mine in that sewer system!!!

12-09-2009, 03:25 AM
Did you use the kerdi drain for PVC pipe? Your's looks black in color (for ABS pipe?). The one I just installed (for PVC) is grey in color. Maybe its just the photo.

12-09-2009, 05:16 AM
Looks like it is the ABS drain connected to PVC with the proper ABS-to-PVC green cement.

12-09-2009, 06:54 AM
I think something people forget when doing their remodel is that this is a system for life. Your Kerdi floor should never fail - ever.

If you are building a shower for life you have to assume that over the course of it's life it will need service. IE their will be built up of hairs and such and a snake here and there will be necessary.

Having one little plastic strap securing your drain is crazy. They make strap tie out of stainless steel, metal, galv metal and copper. That P trap and line should be well secured so that one day a plumber can come in a snake it.

If your drain is loose now I'm thinking you just push it up, apply more thinset and then drop a 5 gallon bucket of water on top. Go to the basement and pack the loose mortar that's oozing underneath. Let this set up and the next day give a little shot of spray foam around the opening.

Looks like by my eye that you have a 1 1/2" line - these are much harder to snake than a 2" line so extra care should be taken to secure the p trap and line.

Good Luck.

12-09-2009, 11:10 AM
There's a gold mine in that sewer system!!!Icky, but true. Ask Roto-Rooter...:D

12-09-2009, 12:16 PM
Looks like it worked. I used an EZbar to pry up the flange and then a small putty knife to shove in as much thinset as I could. It's not perfectly level with the rest of the styrofoam floor, but it's not more than 1/4"...prob more like 1/8" off. But, at first inspection (just now) it seems to be solid all the way around from hand pressure.

I hope the whole thing works as designed.

FYI...there was nothing oozying from underneath. Per my previous post, the styrofoam was well embedded to the floor. This turned out to be specific to the flange to the foam..again off by 1/8-1/4" making it springy. But, not anymore.

12-09-2009, 12:21 PM
As for the's not holding the line UP. Trust me. I literally tried pulling down on that thing and it didn't move.

Yes it goes from copper to pvc to abs..I know, a little screwy. Yes, the plumber used the appropriate pvc to abs (green) cement.

The lines in my house are all copper, EXCEPT this one that is PVC that happened from the previous remodeled shower done over 15yrs ago when they put in a fiberglass shower after what appears to have been some water damage. I know this from my recent evaluation of the bathroom floor, ceiling in the garage and subsequent floor supports we put in and the new drain.

As for drainage issues...had 1 one time from too much garbage in the garbage disposal that I personall snaked out. Never have had any other 15 yrs and two kids (not yet teenagers).

Houston Remodeler
12-09-2009, 03:50 PM
The kerdi flange doesn't need to be all that level. When you go to set the drain itself, you have full control over all axis to correct any tilt.

12-09-2009, 04:15 PM
YAHOO!!!! Thanks! That's spectacular to hear.

12-09-2009, 04:18 PM
The kerdi flange doesn't need to be all that level. When you go to set the drain itself, you have full control over all axis to correct any tilt. Perhaps I'm missing something here, but I want my Kerdi drain, and associated flange, very level when installed.

Perhaps somebody can 'splain me why that wouldn't apply here.

My opinion; worth price charged.

Houston Remodeler
12-09-2009, 04:26 PM
We make every effort for our flanges to be level too. Our tavy puck was purchased specifically for that purpose.

Sure a level flange is nice for laying the tile. But as far as the functioning of the drain its not. A slight angle on the flange can easily be overcome when setting the floor tiles. The drain can be tilted when it set to fix any discrepancy with the flange.

12-10-2009, 02:27 AM
The flange definitely needs to be as level as possible. It would probably be difficult to get one side level and the other side being back-falling without cracking the drain. But, the flange of the drain is already sloped, so unless it is pushed WAAAY down, it's probably not back-falling. It's just easier to set it level and know that it's going to drain properly than to try to make up the difference with the tile.

Having said all that, it looks like the drain in this house has already been attached anyway, so it's a moot point. :)