FYI, I also extended my back rooms all the way to the back above my wet kitchen. This got approval from MBPJ. Submitted all the drawings and everything. I think the limiting factor is the lane behind separating the row of houses. Must be 10 feet or more (I think).

As I've found out, rain leak is some times not so easy to track down. I have (hopefully, had) a leak from my roof in the stair well from the shared wall with neighbour. Can see wet water mark on the plaster ceiling board. Contractor came and tried to patch it up a few times with silicone or something, but it still leaked. It's now dried out, and hopefully it will stay dry. Have to wait for some heavy rain and wind before can confirm.