Section 53(2)(a) in West Bengal Municipal (Building) Rules, 2007
(a)In case the whole of one side or part of at least two sides of every room excepting bath, water-closets and store-room, is not abutting either the front open space, rear open space or side open space, it shall abut an inner courtyard whose minimum width shall be 30% of the height of the building or 3 metres, whichever is more;