Do you need a cushion for roof waterproofing?
If the base layer of the waterproof layer is flat or in line with the requirements of the waterproof material process, you can not do leveling layer. For example, in the cast-in-place concrete roof with the pound with wiping light, may serve as the waterproof layer of the grassroots.
Roofing layer of leveling layer is usually used 20mm thick 1: 2.5 cement mortar. The leveling layer may be made directly on the structural concrete surface, or it may be made on the insulation layer and is provided for the construction of the waterproof material.
Where the process (such as waterproof material construction, floor construction, equipment installation, etc.) on the grass-roots level have certain requirements, must be grass-roots leveling treatment, in the project, commonly used leveling method is to use a certain strength of cement mortar or Fine stone concrete leveling.
There is no "cushion" on the roof, and there is a concrete cushion under the basement floor. What you said may be leveling, is the base of the waterproof layer.
