One of the most frequently asked questions during bathroom renovations is - Can you tile over existing bathroom floor tiles or wall tiles? - Well, technically you can lay new tiles over existing tiles. However this method of tiling highly depends on the condition of the existing tiles.
Since you are renovating the floor tiles or wall tiles because they are worn out, damaged or out-dated, tiling over the existing tiles is generally not advisable. Why? There are a wide variety of reasons, but the main is that the adhesive for the new tiles may not stick as well to the existing tiles as a concrete bedding because of the humidity, movement or condition of the existing floor or wall.
Tiling over existing ceramic tiles in your bathroom is a great way to save a bit of cash by not having to pay someone to rip up the existing job, there is also less cleaning involved.
Nerang Tiles has provided some tips and tricks below to help you consider whether you wan to tile over your existing bathroom floor tiles or bathroom wall tiles.
Before you start
Special materials specifically designed for nontraditional surfaces are required when tiling over existing tiles.
If you are tiling over tiles that have a matt finish then the best adhesive to use would be any non slump, flexible tile adhesive that has a C2S2TE classification that can be installed in accordance with Australian Standard AS3958.1-2007.
If you are tiling over tiles that have a gloss finish then the approach is just slightly different. Before installing the tiles you will need to prime the existing surface of the tiles by using a specific tile primer that will need to be applied by a roller to the existing floor. Once the primer has dried then a rubber based modified adhesive can be applied.
It is critical that you properly inspect the condition of the existing bathroom floor tiles or bathroom wall tiles because they are the foundation of your new tiling job. Any tiling job needs to be properly sealed and bond with its base. If your existing bathroom tiles are well laid, there are no hollow gaps underneath or humidity issues, then it should be okay to lay the new bathroom tiles.
To inspect and prepare the surface properly, you can check for cavities in the existing tiles by gently tapping on them with a rubber or wooden hammer to search for hollow sounds. These gaps or cavities are usually caused by the lack of adhesive between the existing tiles and the subflooring but can also be caused by movement in the surface.
Make sure that the floor tiles and wall tiles are leveled, any spots that are elevated should be grinded down with a right angle grinder fixed with a masonry wheel.
Sand all the tiles with a belt or orbital sander to scratch out any surface glazes. This will create a rougher and more porous surface which will help the adhesive bond to the existing tiles.
Vacuum and clean the tiles with detergent and water to remove any grime, dirt, sealers and wax. Rinse the surface of the old tiles with clear water and let it dry.
After you have prepared the floor, all that is left is for you to glue your new tiles to the existing tiles in your bathroom floor and wall. Tilers recommend using a rubber based glue for this job. This will provide more flexibility as the ground and existing tiles move slightly throughout the seasons.