Worried about removing replacing existing tile over mortar bed


Replacing Existing Tile over Mortar Bed - I have porcelain tile in my kitchen, installed by previous owners. Cabinets, fridge, stove, etc, are on top of the tile. The tile is white, picks up all dirt, food, etc and I want to replace. Contractors I've talked to are worried about how to remove it; if it was laid with a 'wet bed" and whether they can safely and professionally remove the tile and lay somethign else down. I can't lay new flooring on top, because it would be too high. I thought this would be a common problem, but apparently, it's not. do you have any suggestions? I live outside of Philadelphia. Thanks--I could really use a professional opinion.


ANSWER - It sounds odd that the installers are saying they are worried about removing the old tile. If it was installed in a wet-set method where they installed the tile over the freshly installed cement mortar bed then I would expect some of the mortar bed to break loose as the tiles are removed, but there is a chance that some of the tiles will come loose without excessive damage to the mortar bed. The tiles should be removed by chiseling laterally to shear them off the surface of the mortar bed. This should not be a problem if the installers are skilled at installing and removing mortar bed installations. After the tile is removed the mortar bed surface needs to be scarified and then any holes or divots in the mortar bed have to be filled with a proper patch material. There is an Installation Guidelines document you can download from our website by clicking here: Tile Installation Guidelines.


6 thoughts on “Worried about removing replacing existing tile over mortar bed

  1. Charles Lutz says:

    I’m demoing a old school the tile was done over block walls with wet bed over the block then tiled in 1969 the tile is soled not lose . Should I remove the old tile that is on old wet bed and block walls or tile over the old tile ? After removing the old tile there are spots that the wet bed is lose or came off down to the block walls as I can see the difference in the wet bet some are sandy and looks like not enough Portland cement. Is it best to leave old tile and tile over the solid wall tile I’m afraid to tongue over loose with that will cause a problem. What is the process to go over uneven web bed that is on block walls

    • Donato Pompo says:

      It is legitimate tile over tile if the existing tile is adequately attached as the new tile installation can’t be any better than the existing tile.

      If some tiles and mortar bed are loose, then I would remove all of the tile and any loose mortar bed. Once you are assured what mortar is left on the wall is adequately attached, then use a modified mortar bed mix like Laticrete 3701 Fortified mortar and adhere it to the existing surface in order to plumb the wall. Just before applying the modified mortar, you must apply a slurry bond coat using a polymer modified thinset mortar like Laticrete 254. It can be applied in more of a wet consistency so you can apply it with a plaster brush. You must immediately apply the modified mortar over the fresh and tacky slurry bond coat. After the mortar bed has set up then you can apply a liquid applied waterproof membrane if you need the tile installation to be waterproof.

      • Shona says:

        Working on a renovation on several changerooms in a community centre with pool. The existing walls are concrete block with tile (built in the 90s). Would it be easy enough for a contractor to take off the old tile and replace it with new tile? Would the method be similar to above? Or would the finish likely be uneven due to the old grout?

        • Donato Pompo says:

          If you tile over the existing tile then you have to make sure the tile is structurally sound and square and plumb on the wall. You can scarify the tile and then adjust it with a patching mortar before bonding to it.

          If you replace all of the tile then the installer has to properly prepare the substrate. They need to grind off any of the residuals from the original installation and then they have to adjust the wall accordingly to make sure all is plumb and square. If necessary you can apply a waterproof membrane over the substrate. A liquid applied waterproof membrane is easier to apply and works well if properly applied. Then they can adhere the tile to the prepared substrate.

  2. Shona says:

    Thankyou. There is a large amount of existing tile. Could you advise if it is more cost effective to remove the old tile and replace it with new as above or to remove the old tile and install furring and cement board then retile? From a contractors perspective which would be the best option?

    • Donato Pompo says:

      It depends. Whether the existing tile application is structurally sound and for wall applications is plumb and square. Same for the floor in terms of being structurally sound, but also that it is properly flat whether there is a slope or otherwise.

      If the the application isn’t structurally sound then you have to start over from the underlying structural substrate. If the walls or floors need a lot of adjusting then it might be more practical to start over. If the applications are structurally sound and properly square, plumb and/or flat, then it would be more cost effective to bond directly to the existing tile installation if done properly.

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