partial mud bed and Ditra? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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12-06-2007, 08:47 AM
OK I have a dilema I am trying to ponder out and have a limited time frame starting now to complete.

Here is the situation.
Yesterday I removed about 125sf of ceramic tile from an ATM entryway. During this process some of the repair and leveling old concrete came up along and still attached to the tile. The entry does take a slope to a back corner away from the 2 exterior exit doors and main entrance door. I am guesing about a 1" to 1.5" slope in 10' span. Also have a fault line where the concrete had cracked. I am not sure of the reason of the slope but possibley it had been exterior before or just had dropped long ago.

Anyway I was thinking of just building up with a mud bed up to the crack and patch/feather out the rest with a portland patching compound. I am not looking for level with this, just flat for this area for 20" porcelian tile.

I also have to slope the tile upwards to the main entry to the bank for wheel chair accessiblity but cannot raise the floor near the 2 side entrance doors.
This I can build up with some patching compound so not a problem.

Main question is can I do just a partial mud bed to raise the lower section, leave a gap between the repair side and the ok side of the concrete and install Ditra over the entire thing?

I have to do this today and hope for suggestions that confirm my thinking is good on this matter..

I will check in frequently as I can.


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12-06-2007, 12:52 PM
I can't tell where your doors are, nor the area to be ramped, Tracy, but I can see that I'd likely be reeeeeal concerned about that area that's sloped away from a "fault line." Gotta believe there's a little vertical component to that crack, too.

Best possible case I can see is that you must honor that crack through the Ditra and Tile. And I don't see how you could make it all flat enough for those large tiles without leveling the whole thing. But maybe you know a way.

My opinion; worth price charged.

12-06-2007, 03:09 PM

I had a chance to do some grind leveling with my 7" makita, diamond cup, dust muzzle, and double filtered shop vac and have found more to it then I could see yesterday. As from I can tell, the crack was actually through a concrete cap over the existing concrete. Concrete below I believe was the exterior concrete many years ago that got capped when they decided to enclose it and make it ATM accessible. Don't believe they honored the joint then so the cap cracked like what the diagram showed. I have since lasered the line and cut down deep enough to find I think is rebar but not sure and basicly create an crack control joint

From what I have found today, examining the Schluter specs, taking into consideration to the type of failure at the grout joint (only one by the way and I was the one who installed the tile back in my very rookie days 18+ years ago :scratch: ), common sense and what you are telling me also I plan on honoring the crack like an expansion joint. I have already worked out with the big wigs of the bank just what I believe is the situation and the possible remedies and consequences of there substrate and they understand what the risks are.

So my remedy is I have cut the control joint, filled with cardboard, will prep and grind the floor more for flatness tolerance, make a slope for the main door and slope the tile to the threshold for wheel chair access, Ditra the floor, and install tile.

Love to explain some more but gotta get back to work to do this :D .
Late nighter again......