The insulation itself can be made of several different materials, including mineral fibre, fibreglass matting or mineral wool.

For improved green credentials, use sheep's wool or recycled newspaper for insulation, not mineral fibre.

Addition of a small quantity of cellulose or mineral fibre prevents drainage of bitumen during transport and placement.

A further method exists for the determination of asbestos, fibreglass, synthetic mineral fibre and ceramic mineral fibre dust in air.