Why do the basics of the cushion waterproofing
The general basis of the foundation, the bar base is not necessary to do, like a raft in the basement, it is necessary to prevent the water from dipping into the basement (so the basement design may have to do anti-floating calculations). Assuming (just suppose) the raft can easily turn over, then we do waterproof (like roof) directly on it, not waterproof on the cushion.
Base cushion waterproofing is not contact with the soil (Ying water) to prevent water into the cushion, but in the cushion and the base of the bottom of the contact, in fact, is the basis of the bottom of the waterproof.
As for the bottom of the bar thickness of the protective layer is generally 4cm, but if the basic floor of the concrete label is relatively high, the protective layer can be appropriately reduced.
Raft foundation do not do waterproof mainly depends on the design of the groundwater level considerations, calculated if the floor itself to meet the requirements, you can not do, and not rigid to do
