New tile can go over old tile only when the old tile is bonded
Tiling over existing ceramic tile is done regularly when the added thickness is acceptable and the old tile is well bonded. The Tile Council points to handbook details TR712 and TR713 for the procedure. Not every thinset, including polymer-modified ones, will bond to tile. The mortar maker has to name a product for that surface.
Bond test and abrasion
Depending on the tile already in place, the surface sometimes has to be mechanically abraded. The FAQ says a bond test is the usual way to decide. Abrasion can release fine particles. The page warns that a mineral analysis should come first and that safety equipment should be worn. The Tile Council lab is one place that can test for toxic metals and shear bond.
What this does not settle
The FAQ does not say every old floor is a candidate. Loose tile, a height limit, or a thinset that is not rated for the surface keeps the overlay off the table.
Source
Fetched 2026-10-11 from Tile Council existing ceramic tile FAQ. The sentences above follow that page. They are not a contractor promise.
Related notes
- Tile notes index
- DCOF is a measured slip value, not a brand name
- Floor stiffness for tile is discussed as L/360
- Backsplash photos
Send photos if you want another person to look at the area. This note does not set a response time.