What started as grinding Away moist grout on shower floor tile Turn into complete removal as well as bottom 6 inches of wall tile. Working on removing the old drain. No sign of weep holes (yet?).

The Sxhutler Kerri system looks easier for a first time DIY but is it really necessary or beneficial to completely remove the mortar bed? Can I just patch up a couple spots and put a new membrane over it?

old mortar bed and drain

1 Answer 1


I have left old mortarbeds in place in showers. In your case, your bed looks quite good.

I do make a habit of smoothing the old surface, so there aren't areas with gaps or pinch points to catch the new membrane on. As long as your new surface meets well with the drain (as in the membrane will seal around the drain and won't be lifting the tile so high you have to grind the edges) it should be fine.

  • Thanks! The little research I"ve done - first time I"m consider a shower pan as 'DIY' - I realize what a horrible job the installers did : totally clogged the weep holes with mortar! There's only 2 weep holes, the drain looks old and ugly, I think it's worth replacing. I"m really curious wether the membrane properly goes up the wall behind the backer board or not....consider the weep holes were clogged, it may be worth the time demo'ing the corner near the wall to see if the membrane goes up properly or not.
    – guitar guy
    Jul 12, 2021 at 15:15
  • Ok - just be prepared for pulling the whole bed, as it's likely it will crack elsewhere when you do this. If the weep holes were plugged since installation, it may be worth the effort to be sure the wallboards aren't compromised.
    – Bee Kay
    Jul 13, 2021 at 16:27
  • So, I pulled the whole bed out and removed the bottom 12" of cement backer board. It was wicking moisture up because it was sitting right down to the membrane and there is NO Pre-slop under the membrane. Between that and mortar over weep holes it was a receipt for failure. I did not remove the existing membrane but looking behind it the framing looks completely dry, yay!
    – guitar guy
    Jul 15, 2021 at 14:56
  • So, I have a couple options here, I wonder if someone w/ experience can offer an opinion, please. 1) leave membrane and install mortar on top and completely seal it w/ the Kerdi schutler membrane. 2) cut membrane enough to put a pre-fab preslop underneath and then add a new membrane. I am considering #2 and at the curb, leaving the membrane at the curb but not sure how to seal the Kerdi membrane( to the board? to the PVC membrane? youtu.be/EHh1pbSYJQo
    – guitar guy
    Jul 15, 2021 at 14:59
  • From my limited experience, if you've pulled out the old mortar, I'd take out the old membrane too, just to avoid any slippage or shifting. Besides if it's fleeced, it's going to be dirty and gritty, and that's not fun to clean before adding another membrane. If you ordered the full shower pan kit, then you are going to be able to save a few inches in height thanks to removing the old mortar, and get a smoother leveled bed out of it.
    – Bee Kay
    Jul 16, 2021 at 21:08

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