Section 10(1) in The Chennai City Corporation Building Rules, 1972
(1)Every person who constructs a dwelling house or other domestic building shall cause every external wall and every main wall to be built, unless otherwise specified by the Commissioner, of at least the thickness specified in Appendix D. The thickness specified in Appendix D shall apply only to walls built in horizontal beds or courses of good whole bricks or of suitable stone or other blocks of hard and incombustible material.
