Sir would you like to explain sunken slab k,first I am say about one thing what you did clearly explain at that part. You are choosing topic the sunken a) What is the advantage of sunken in our house or flat. b) how it is work after laying concrete slab. C) In which water ratio of concrete pour in sunken slab . D) how to fix plumbing line sleeves on before concrete in sunken beam. E) what's the slope maintain on sunken slab above. F) how to fixing electrical pipes before concrete in sunken slab. Etc more details are having in sunken slab. so I request you to discuss with structural engineer. Why I am telling you know many things,but how it's work. More viewers were watching your videos and they will be implement in those ideas. which and all learning your carrier or work . You taught others engineer that's very good habit . Keep it up. Thank you