Does cement expand

The thermal expansion of fibre cement sheet is very small. Over the size of a 2400mm sheet, for a temperature change of 30°C, there would be much less than a millimetre change in the length of the sheet.

The expansion joints required between sheets are necessary to accommodate the movement and expansion of the material to which the sheets are fixed, which is usually much greater than that of the fibre cement sheet. (For example timber, steel, aluminium, and plastics expand more than fibre cement.)