Preparing surface when tiling over existing tiles

Question

I'm retiling our bathroom and intend to tile over the top of the existing floor tiles. The floor is in fair condition at the moment with no cracking except in one place which I did myself and will fill before tiling.

Apart from cleaning off the tiles with sugar soap, is there any special preparation I need to do to the existing floor, such as scuffing the tiles for the cement or filling in the existing grout? I've never done any tiling before.

Answer 1

• Step 1: Remove existing fixtures (toilet, sink, etc.)
• Step 2: Remove existing tile.
• Step 3: Determine if existing sub floor is appropriate for tile.
• Step 3 a: Replace existing sub floor (if necessary).
• Step 3 b: Install appropriate sub floor.
• Step 4: Install new tile.
• Step 5: Reinstall fixtures.
• Step 6: Enjoy your new bathroom for years to come.

This may not be the answer you are looking for, but to do the job right (in my opinion) you should start fresh.

If you don't feel comfortable doing the job yourself, you might think about hiring a professional.

I apologizes for the bluntness of my answer; as a home owner myself who has had to fix the messes others have created, in my opinion there is no excuse for not doing a job properly and (as Mike Holmes would say) making it right.

Removing the existing tile will cost you nothing but time, and in the end it will make you feel much better knowing that you can enjoy the remodel for years to come trouble free.

Answer 2

Tester101 is right in that doing the job right would require removing the old tiles. Personally, I find that to be great stress relief, since it can involve liberal use of a sledgehammer. If you need a quick-and-dirty method, try this:

1. Remove fixtures.
2. Cut up some underlayment (birch is probably best) to the shape of your floor
3. Rough up extant tile
4. Apply construction adhesive liberally to back of the underlayment and stick it to the roughed-up tiles.
5. Tile normally on top of underlayment, taking care that seams between tiles and edge of the underlayment don't line up.
6. Put new saddles at transition areas (i.e. the doorway) on edge of tile.
7. Reinstall fixtures

This won't last as long as doing the job right, but it may well be quicker and is a "good enough" solution if you need it done quicker than normal and don't care about the work lasting (e.g. if you need to redo the tile quickly to help sell the house).