Section 18(2) in The Chennai City Corporation Building Rules, 1972
(2)Windows and ventilators which open into a verandah shall be deemed to communicate with the external air, provided that such verandah is not more than three metres and seventy five centimetres wide and open throughout its entire length into space open to the sky, the width of such open space being double the width of the verandah and in no case less than one metre and seventy five centimetres.
