Symptoms
- Hollow or drum-like sound when tapping the tile
- Slight movement or flex when stepped on
- Grout cracking around the loose tile
- Tile may rock slightly if pressed on one corner
Likely causes
- CommonInsufficient thin-set coverage during original installationGaps or voids under the tile leave it unsupported in spots, sounding hollow when tapped.
- CommonSubstrate flex or movement over timeA subfloor that isn't rigid enough lets the bond gradually fail.
- PossibleMoisture breaking down the adhesiveWater intrusion from below or through grout can weaken thin-set over time.
- PossibleAge and normal adhesive failureEven good installations can loosen after many years.
What to do
- Tap across the floor with a hard object (like a coin or the handle of a screwdriver) to map out exactly which tiles sound hollow.
- Mark the affected tiles lightly with painter's tape.
- For a single loose tile that isn't cracked, sometimes an epoxy injection kit can be used to re-bond it without removal, though results vary.
- For more reliable results, remove the loose tile using a grout saw around the edges and a chisel to lift it carefully.
- Clean out old thin-set from both the tile back and the subfloor.
- Reapply fresh thin-set with a notched trowel and reset the tile, using spacers to match the surrounding grout lines.
- Let the thin-set cure, then regrout and let that cure before walking on the area.
Tools and parts
- Grout saw
- Chisel
- Notched trowel
- Tile spacers
Tile thin-set mortarSearch: “tile thin-set mortar”
GroutSearch: “matching tile grout”
When to call a pro
Call a tile installer if multiple tiles across the floor sound hollow, since that often points to a broader substrate issue.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.