I removed some tiles today and found not just thinset and an underlayment but a few layers of mesh and what appear to be stones or concrete. What is this, why was this used and is there anything special I should know about removing it?

I'm also replacing it with other tile, was thinking of just underlayment on the wood subfloor. Will that still work?

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  • Looks like old backerboard.
    – Jon Custer
    Dec 4, 2022 at 17:12
  • Hammer and chisel will work
    – asinine
    Dec 4, 2022 at 17:44

2 Answers 2


Unfortunately you have to remove (hammer and chisel) it down to the base board.

The new tile job requires it to have clean flat surface.

You can not tile on the existing surface.

That was older method of preparing the floors for tiles, before they invented backer boards.

  • Thanks! What’s your estimate then on when these tiles were installed? The house is from the 1970s but they were in good shape, I thought they were put in within the last 5 years, but maybe not? Dec 5, 2022 at 3:07
  • @podcastfan88, sorry I do not know that, and yes they did good job back than
    – asinine
    Dec 5, 2022 at 4:14

It's a TCNA (Tile Council of North America) F141 or F145 (mortar bed, aka "mud job") base layer, and removing it (rather than just popping the tile off of it) is needless waste of effort since you plan to put tile back here.


It's an exceedingly good base for tile. The tile jobs in old houses that have lasted for 100 years - they were done this way.

  • regarding peeling the thinset off the concrete: diy.stackexchange.com/q/41642/18078
    – Ecnerwal
    Dec 5, 2022 at 3:39
  • Are you sure you can tile over this? After pulling up the other tile it's a mess, some thinset and all kinds of wobbly bits. Dec 6, 2022 at 1:35
  • Knock off (see above linked question/answer) and/or grind down any thinset sticking up. Full any major divots and the hole you bashed. If by "wobbly bits" you mean it's broken up then it's toast - it should have been possible to split the tile off without major damage, working with a wide chisel. If it's just scars and divots, they can be filled. If it's crumbling, take it out.
    – Ecnerwal
    Dec 6, 2022 at 1:51

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