1. Tap
Locate loose or hollow areas by tapping with a wooden dowel or broom handle. Mark the perimeter with chalk or tape.
2. Drill
Use a masonry bit (1/8", 3/16" or 1/4") that fits the grout line without touching tiles. Drill straight down; stop when you hit the void.
3. Vac
Vacuum each hole to remove dust and debris. Light taps with a rubber mallet help loosen residue.
4. Fill
Cut the tip for a snug fit. Pierce the tube seal, refit tip and slowly inject Fix-A-Floor until adhesive appears in nearby holes.
5. Weight
Place a heavy bucket (or similar) over the area. Wipe excess adhesive. Allow to cure for at least 24 hours.
6. Grout
Fill holes with colour-matched grout. After 15–20 minutes, smooth with a damp cloth. Let dry and wipe clean.