New wall tile over old dried mortar [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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08-04-2001, 10:21 AM
I'm re-tiling in a tub/shower. I have removed the old tile which left the old mortar surface that's really rough. Do I need to smooth this over a bit or can I just re-tile over the old surface?

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Bud Cline
08-04-2001, 10:35 AM

This would depend on the varying perceptions of "really rough" but I wouldn't think there would be a problem.

By "really rough" do you mean you have damaged the subwall when removing the tile? Do you have divits in the wall? Can you tell what adhesive was used to install the tile? You really shouldn't see remnants of adhesive if thinset on mud base was the method.

Questions, questions, there's a million questions!

08-04-2001, 01:57 PM
Well Bud, perhaps I exagerated a bit regarding "rough". After further review, it's more pock-marked than anything else...but the pocks are significant. One "tile guy" said to use a fast dry thinset first then go with the normal thinset after about 30 minutes. Does this make sense to you?

Rob Z
08-04-2001, 02:03 PM
Hi Lex

Depending on just how big these missing chunks are, I would use a product by Ardex called Tilt Wall Patch. It won't sag in deep applications the way the thinset would. And, it's fast drying as well.

Their website is


Bud Cline
08-04-2001, 02:57 PM
I don't know what size tile you plan to use but if it is traditional 4-1/4" (4-3/8") then those divits will more than likely cause you trouble. I think I would do as Rob suggests and probably just skim the whole wall.

This process will more than likely then have to be stoned (sanded) to take down the highs you will probably end up with. I use a handled corborundum stone for this type work and it will get into the corners real well also.