I would like to add my thoughts to the discussion for the recently-posted article titled “Hollow Sounding Tiles and Spot Bonding” written by Stephanie Samulski (TileLetter TECH issue, November 2018). The article makes a number of valid points.
I agree that as part of any comprehensive inspection of installed tile, it is essential to identify both the condition of the substrate and the method and materials used. In investigating the potential causes of hollow-sounding tile is important to document step-by-step the installation methods used to determine if it is a failing floor or just sound transmission.
I personally would be upset if my floor sounded hollow following a tile installation. Prior to installing the tile, it would important to discuss with the client that in certain situations it is possible that the use of some materials could cause sound transmission similar to tiles that are inadequately bonded. Furthermore, I agree that since a variety of factors may contribute to a hollow-sounding floor, it may be difficult to definitively reach a conclusion about the cause of the hollow-sounding tile. However, I have installed many thousands of square feet of tile in my lifetime and inspected many installations with hollow-sounding tile. I have frequently observed a failing floor with inadequately-bonded tile, and just a few instances in which hollow-sounding tile was perfectly bonded.
For instance, I recently inspected a mall for an architect who complained of hollow-sounding tile. I asked the architect to mark the most irritating tiles and removed the tiles in his presence, and found that the tiles were well-bonded. Removing tiles during an inspection, in my opinion, is the only way you can truly prove that the floor is properly installed and that the sound transmission may be resulting from the installed floor assembly.
With the increased use of membranes, it is important to understand the risk of sound transmission. As Stephanie mentions, the use of ceramic tile will transmit sound even more so than a denser material such as natural stone. I would always advise getting a second opinion from someone who is versed in the tile installation business. And if it’s bothersome –and attic stock exists – I recommend removing a tile to check for issues.