Are hollow-sounding tiles present elsewhere in the home? Voids under the tiles outside the failure area may indicate installation problems.

Are hollow-sounding tiles located along walls and partitions? Slab contamination often comes from paint and construction residue, which is usually heaviest along walls.

Are there expansion joints in the tile floor? Industry standards recommend expansion joints 24' to 36' in each direction for interiors, and 12' to 16' in each direction for exteriors. Interior surfaces exposed to direct sunlight or moisture should contain expansion joints 12' to 16' in each direction. Joints should also separate large rooms.

Has the thinset mortar separated cleanly from the tiles? If so, then a proper bond may never have formed between the mortar and the tiles. Check to see whether the tiles were pressed firmly into the mortar.

Has the thinset mortar separated cleanly from the slab? If so, then a proper bond may never have formed between the mortar and the slab. Check for slab contamination.

How thick is the mortar bed? The thin-set mortar should be 3/16" thick, or thicker, if there are lugs on the back side of the tiles.

Are there any signs of structural settlement in the exterior of the building, or cracks in the slab? Differential slab movement can stress the tile plate and cause failure.

Is the top of the floor slab well above the soil level outside, and is there good site drainage away from the building? Under some conditions (rare in South Florida), water may be forced upward through the slab by hydrostatic pressure, causing tile failure.

What is the age and type of the tile? A ceramic tile made before 1980 may be more porous than contemporary tiles, and may be susceptible to moisture expansion. Unsealed clay tiles may also expand when wet.

Look at the walls. Can you see cracking at wall-to-soffit and wall-to-ceiling joints? Vibration tends to cause damage in the upper sections of a structure before affecting its foundation slab.

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