Thermal movement is the effects of a change in temperature that causes material to contract or expand.
There are two types of thermal movement that can affect buildings: thermal expansion and thermal contraction.
Thermal expansion happens when a building is exposed to high temperatures; for example, in a bathroom where there is lots of steam from hot water or in a kitchen with hob and oven in use.
Thermal contract happens when the structure is exposed to extremely cold temperatures.
The effects of thermal movement can be seen in cracked brickwork, broken window fittings and sloping floors.