Sheet sizes vary slightly from manufacturer to manufacturer but generally they range between 2400 – 3000 mm in length and 900 –1200mm in width (600 & 450 mm increments). This manufactured size minimizes on-site wastage as residential floor, wall and roof structures lay structural members at 450 or 600mm centres.
When used as siding boards, widths between 130mm and 300mm (5.25 inch to 12 inch) are available. fiber cement thicknesses vary between 4.5-18mm and also vary in density – the lower density resulting in a fibrous rough edge when cut and the higher density having a cleaner smoother edge when cut.
Thermal resistance and sound transmission can vary greatly between fiber cement products. fiber cement sheet products rate poorly in thermal resistance and sound transmission and separate wall insulation is highly recommended. Generally the thicker and denser the product the better resistance it will have to temperature and sound transmission.
Selected from: https://en.wikipedia.org/wiki/Fiber_cement_siding#Usage