What is waterproof (with slate)
as well as In the summer when the sun is direct, absorb a certain amount of heat, to prevent the softening of the waterproof material heat
the stone layer covered in the upward side, on the one hand it played a protective waterproof layer role
Slate is in the waterproof material on the upper surface of the particle size of not more than 4mm small stone layer, bonded to the roof
