Section 67 in Kolkata Municipal Corporation Building Rules, 2009
67. Interior open space.
(1)In case the whole of one side or part of at least two sides of every habitable room is not abutting the front, rear or side open spaces it shall abut an interior open space. Interior open space at ground level shall be called courtyard.(2)Any room, which is separated only by a verandah from that interior open space, shall be deemed to abut on such interior open space for the purpose of this rule.(3)The minimum dimension of any side of every interior open space (a) 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 m., whichever is more (b) at any other level, all sides of which are enclosed by a building or part thereof, the height shall be measured from the said level where interior open space is formed.(4)Notwithstanding anything contained in sub-rule (3), if all sides of an interior open space are enclosed by a combination of higher and lower blocks of a building, then minimum dimension of such interior open space shall be governed by the height of lower block provided that in no case the covered "area of" such lower block shall be less than-25% of the total Covered area of the concerned building constituting the interior open space.(5)For the purpose of this rule, if any interior open space or courtyard enclosed on three sides by a building or part there use of is meant to serve lighting and ventilation purpose to a part or whole of one side of one or more habitable rooms, then the minimum width of such open space shall be 2.4 m. for buildings upto 15.5 m. in height; 3.5 m. for buildings above 15.5 m. upto 25.5 m. in height; 5.0 m. for buildings above 25.5 m. up to 40.0 m. height; and 7.0 m. for all buildings above 40.0 m. in height.Provided that the depth of such open space shall not exceed twice its width and the same may be reduced to 1.2 m. if no habitable room, or balcony attached to the habitable room is facing the interior open space. However, in case the depth of such interior open space is less than the width, the same shall not be considered as interior open space, but be called as "notch" and the same will be permitted without any restriction.(6)A ventilation shaft having no access to the same except through one door for service purposes shall not be treated as a courtyard, if the area of such shaft is less than 20 sq. m.
