Quartz is marketed as virtually indestructible — and for most purposes it is. But quartz worktops do crack, and when they do it is often unexpected and alarming. Here are the most common causes.

Thermal Shock

The most frequently cited cause of quartz cracking is thermal shock — placing a very hot item directly onto the cold quartz surface creates a sudden temperature differential that can cause the material to fracture.

Quartz worktops contain resin binders that are more sensitive to heat than the quartz particles themselves. Sustained or extreme heat can cause the resin to degrade, leading to surface crazing or cracking.

The fix: always use a trivet or heat mat. Never place hot pans, baking trays or steam-generating appliances directly on a quartz worktop.

Inadequate Support

Quartz worktops are heavy and rigid. If the underlying cabinet structure does not provide adequate support — particularly at long spans, over dishwasher openings, or either side of hob or sink cutouts — the worktop can flex under load. Repeated flexing eventually causes fatigue cracking.

The fix: ensure worktops are properly supported during installation. Additional support brackets can be retrofitted in some cases.

Impact

A sufficiently heavy or sharp impact will crack quartz. A cast iron pan dropped from height, a heavy appliance moving across the surface, or significant mechanical impact during building work can all cause cracking.

Sink Cutout Stress Concentration

The corners of sink cutouts are stress concentration points. Cracks radiating from sink cutout corners are common on quartz worktops and are often related to one of the above causes acting at the weakest point.

Manufacturing Defects

Occasionally, quartz worktops crack due to internal stresses introduced during manufacture. If a crack appears without any apparent cause, it may be worth raising with the manufacturer or supplier.