Common tile problems: hollow tiles, tenting and cracking, grout cracks, and white salts

Tile is one of the longest-lasting finishes when installed correctly, and most tile problems come from the installation rather than the tile. For the basics see tile installation and adhesives.

1) Tiles lifting, tenting or suddenly cracking

Without movement joints, the tile assembly has no room to expand, so the tile pops up or "tents", most often in the middle of the floor, even if the rest of the installation was done correctly1. Tiles move with temperature changes and environmental conditions.

Per the Tile Council of North America (TCNA) Handbook, as summarised by CTEF1:

• At perimeter walls: at least 6 mm (¼ in), usually covered by the skirting.
• Changes of plane (floor meeting wall): at least 3 mm (⅛ in).
• Exterior areas: at least 3/8 in (9.5 mm) wide for joints 8 ft (2.44 m) on centre, and 1/2 in (12.7 mm) for joints 12 ft (3.66 m) on centre, widened 1/16 in (1.6 mm) for each 15°F of tile surface temperature change above 100°F between summer high and winter low.
• Tile exposed to direct sunlight or moisture: preferably 1/4 in (6 mm), never less than 1/8 in (3 mm).
• And the TCNA statement CTEF quotes: movement joints are not optional — they are a requirement.

2) Hollow-sounding ("drummy") tiles

A hollow sound usually means a void under the tile from insufficient adhesive coverage. Installation guidance calls for high coverage under the tile, especially in showers, exterior areas and natural stone tile2. Details in tile installation.

Not every hollow sound means lifting the tile; but a hollow tile in a busy walkway, with cracked grout, or in a wet area is a candidate for cracking or letting water in (practical note).

3) Grout cracking or falling out

• At corners and changes of plane: these are movement joint locations and need a flexible sealant, not grout1.
• In the middle of the floor: may indicate substrate movement or hollow tiles.
• In bathrooms: cement grout not suited to the location; see grout types.

4) White salts on tiles or grout

White efflorescence is salt deposits carried to the surface by moisture moving through mortar or concrete, and needs both salt and moisture3. Treatment starts with finding the moisture source. See damp walls and waterproofing under tiles.

5) Tile handover checklist

1. Tap samples of tiles gently with a handle or coin; note hollow sounds.
2. Check movement joints at walls, thresholds and large areas, filled with a flexible sealant.
3. Check flatness and alignment of joints.
4. In bathrooms: test the falls by pouring water and watching it run to the drain.