Hi people. Got some questions to ask regarding extension rules and limitations.

For a Semi-D residential house, specifically the side and back portion of the house, what are the regulation in terms of boundaries ? I searched google and it says can only extend maximum 3 meter starting from the walls. If so, how much space should I be leaving between my walls and the neighbor’s ?

My scenario is that I wish to extend the side portion 4 ft out, which will be 1.2 meter. Any advice ?