Structural level of sloping roof with Grade 1 waterproof tile

1. Roof thermal insulation layer.

2. Roofing waterproof layer (there are two kinds of roofing waterproof layer: flexible waterproof layer and rigid waterproof layer).

3. Roof leveling layer (waterproof can only be done after leveling after finding slope).

4. Find a slope layer for the roof (although it is said to be a "flat roof", it still needs a certain slope to facilitate roof drainage).