Why Does My Floor Tile Sound Hollow?

Ceramic, porcelain, and natural stone floor tiles can sound hollow when tapped on with a metal object.

There are varying reasons that tile floors can sound hollow and it does not necessarily mean that there is a problem. There are some assemblies that will sound hollow by design, such as a non-bonded mortar bed application or assemblies installed over wood subfloors. In these types of assemblies, the hollow sound should be consistent throughout the installation area without stark contrasting sounds.
 
However, when the tile is directly bonded to a concrete subfloor, hollow-sounding tiles could be a reason for concern as most installations should only have very minor areas that sound hollow. In these types of assemblies, if there are very distinct different sounds of solid and hollow spread around, then this may be a situation that requires further investigation.
 
Hollow sounds themselves are not a defect but they are often the symptom of an underlying defect. One common reason that floor tiles sound hollow voids in the adhesive mortar that bonds the tiles to the concrete. If proper installation techniques and methods are not used, it can leave voids that are small or large and produce hollow sounds. Even worse, some installers deploy a method called spot bonding which is where they will put four or five spots of mortar at the corners of the tiles and leave the reaming area free of any mortar at all. This type of installation is not acceptable by any means in flooring applications and should be looked at.
 
The best thing to do if concerned with hollow-sounding floors is to contact us so we can discuss details of the installation and determine if anything needs to be done or not. Sometimes, the worst part of a hollow sound will be the sounds themselves, but in others, it can represent the start of a flooring failure.  It is probably best not to take a chance, especially if the installation was recently installed and recourse is an option to pursue.