The sheet vinyl must be clean and free of wax . This is true of any surface to which you are trying to bond tile. Mortar and adhe- sive manufacturers generally require clean surfaces for bonding any type of thinset. In order to get good solid bonding, the adhe- sives must be able to intimately contact both bonding surfaces (in this case the back of the tile and the vinyl). In the case that either of the surfaces are dirty with grit, oil, wax, or other bond inhibiting films, a good bond cannot be achieved due to the fact that the adhesive isn’t able to contact the necessary surfaces, physically or chemically.
Because the vinyl often has a very smooth surface finish, scarification is required to enhance its bondability. Sanding or scarify- ing enhances the probability of strong phys- ical bonding between the adhesive/tile/vinyl by providing more surface area on the vinyl.
WARNING: If you are going to scar- ify or sand the floor prior to installing tile, it’s important to know if the vinyl contains asbestos. Flooring containing
asbestos should definitely NOT be sand- ed! If you’re unsure, you can cut a small sample (only a small piece is generally needed ~1-inch-by-1/8-inch) and have it tested at a local asbestos testing labo- ratory (found in the Yellow Pages) for a nominal fee if time permits. The health risks of sanding a floor containing asbestos has to do with the harmful air- borne particles which will be generated.
In some cases a cushioning layer is installed underneath the vinyl or the vinyl sheet itself is cushion backed. For tiling purposes, this will allow too much movement in the system and may lead to a failure in the tile layer. Even if the tile and vinyl form a good bond together, if the vinyl isn’t secured to the substrate or allows too much bending, the tile could fail. In addi- tion, in the case of future repairs where one tile had to be replaced, removing a tile from a vinyl substrate which is poorly bonded to the sub- floor could lead to damage in adjacent grout and tile.
The vinyl must be bonded using a full spread adhered system and must not be perimeter tacked. This also provides stability in the vinyl as a substrate. A system which is only tacked at the perimeters will again allow too much movement.
Should I actually AVOID tiling over vinyl?
Although it may seem intimidating or more risky than tiling over other surfaces, well-adhered vinyl with the proper surface treatment to enhance bonding, will work well and may even resist limited horizontal movement.
So what’s the ‘final on vinyl’?
We will have to look at the existing floor and them give you our best advice