What materials are used for roof insulation?
There are two kinds: one is a kind of cotton insulation board, such as rock wool board, aluminum silicate cotton board, but this is not environmental protection, harmful to life, foam board (this fire safety factor minimum), these relatively cheap.
The other one is inorganic insulation materials, such as Portland, rare earth insulation, the thickness should be 5 cm or more, up to the high cost of auxiliary materials of construction, to reinforce, new inorganic insulation material, the material thickness, on the line of 2-3 cm, direct smear on the top of the house, without auxiliary material, than the price of wool, high aluminum silicate cotton.