If the floor sounds hollow, does it mean my tile will crack?
Occasionally, a floor will sound hollow even when the tile is well bonded. This can occur when a mortar bed method is used and the mortar has delaminated from the supporting layer or when the subfloor itself is not sufficiently thick or well attached. Other systems that intentionally separate the tile layer from the substrate (such as the mortar bed with a cleavage membrane system like TCNA Handbook detail F111) should be closely examined to ascertain if hollow sounds necessarily imply that the tile is not bonded.
While a tile floor with hollow spots is not ideal, it does not necessarily mean that floor failure is imminent. On the contrary, over concrete, if there is no deflection in the floor; grout and gravity will help keep the floor in place (as long as there are sufficient movement joints in the tile and minimal shear forces). Over wood, floor failure is more likely. Movement in the subfloor could cause grout to break away from the tile, compounding the instability of the flooring.
Are there any other reasons I might have cracked/loose/hollow tile?
There are many factors that can cause tile to lose its bond to the subfloor. Losing bond to the subfloor has the potential to lead to cracking in the tile layer:
- Expansion and contraction, especially if movement joints were not placed sufficiently in the tile layer. Note: for outdoor, indoor but sunny, or moist installations, this is especially important.
- Poor quality thinset, especially where some shear forces (from expansion and contraction or deflection) are present.
- Paint or lacquer overspray on the subfloor.
- Sealer applied to the subfloor.
- Moisture induced deterioration of the subfloor.
- Delamination of the subfloor.
- Excessive deflection.
- Poor thinset coverage, thinset applied in “dabs,” thinset used beyond its pot life, or thinset that was disturbed as it was curing.
- Moisture sensitive adhesive (affected by hydrostatic moisture or flooding).
Only an on-site inspection can truly evaluate the potential reasons for cracked tile. Please visit the TCA Team for information on these types of services.
Can I inject epoxy under the tile to fix the hollow sound?
Some contractors have tried to inject epoxy to rebond tile without reinstalling it. While this may work in a small area, it is not practical over a large area. Further, any repair that does not address the cause of the failure may not last very long.