There is a 90 cm basement in our building. There is a 90 cm basement on the raft foundation, but I want to enter the building by climbing 6 steps from the inside by stairs. ... I think you understood my question or I want to create a level difference on the same floor. For example, there is a shop on the ground floor, the height of the shop is 390, and there is an apartment on the same floor, its height is 300, so I want to put a 90 cm subfloor under the flat. What kind of a way should I follow to put a shop without a plinth and a flat with a plinth on a raft foundation on the ground floor? Good luck with...