Section 50(3)(a) in West Bengal Municipal (Building) Rules, 2007
(a)For inner courtyard—(i)in case the whole of one side or part of at least two sides of every habitable room is not abutting either the front open space, rear open space or side open spaces, it shall abut an interior open space. Interior open space at ground level shall be called courtyard.(ii)Any room which is separated only by a verandah from the interior open space shall be deemed to abut on such interior open space for the purpose of this rule.(iii)The minimum dimension of any side of every interior open space (e) at ground level all sides of which are enclosed by a building or part thereof shall be 30% of the height of the building or 3.0 metres, whichever is more (b) at any other level, all sides of which are enclosed by a building or part thereof shall be 30% of the height of the building or 3.0 metres, whichever is more, measured from the said level where interior open space is formed.(iv)Notwithstanding anything contained in these rules, if all sides of an interior open space is enclosed by a combination of higher and lower blocks of a building, the minimum dimension of such interior open space shall be governed by the height of lower block;