I am making some changes in my house. One of them is to extend the room area i.e. Drawing room towards the road. Its already size is 30X30 and i want to extend it to 30X737. now i have removed its front wall i.e. road side and having door where i want to extend. The road level has been reached to its DPC level. Please tell me on what level DPC should be placed. my Masson recommend to level up to 4 feet. wooden roof has already been removed.