To tile over old tiles or not?
 

Getting ready to change the tile on my bathroom floor. Its ugly but its in good shape. Its well bonded to the concrete underlayment. I'm wondering is it best to tear up the old tiles or just go right over them. I know I have the option both ways, I just don't know which is best.

If none are loose, tap on them, if it sounds hollow anywhere, remove it all, if solid and the added height isn't a problem, you can go over them with a good modified thinset.:)

Oh wait, you asked which is the best way, removel of all the old and redoing the substrate is best, but if solid, no loose grout and cleaned, don't see a problem, it's done all the time.:)

And If I did decide to remove the tiles first, I'd have to redo the substrate as well? Its an 11/8 concrete slab and Would not be fun to try and take up I'm sure. I don't think I'd mind taking up all the old tiles, but I dont' think I have the time to redo the substrate...

You don't necessarily need to re-do the substrate or take it up. I am in the midst doing a similar job on my own home, albeit a smaller area. What I am experiencing by taking up the old tile (it was a horrible tiling job) and what I think R&D is referring to is that when you remove the old tiles & thinset, parts of the concrete floor will come up with it. So, you need to properly prep the concrete floor. What I am doing to get the floor prepped for the new tile is using self leveling concrete to get the substrate ready for the new thinset and tiles.

Hope this helps...

So you are using self leveling concrete to fill in the areas that come up? I'm not sure I trust myself with concrete to ensure a perfectly level surface - I know that's why its usually only pros that use concrete. I guess its something to ponder for a while. Thanks.

When you say concrete underlayment, are you talking about a slab, a backerboard or a couple inches of mud over a wood floor?:)

Best to start brand new.

Sorry, 1" 1/8 Slab of concrete.