Section 142(4)(c) in West Bengal Municipal (Building) Rules, 2007
(c)in the case of residential buildings or flats where maximum height of rooms measured from the surface of the floor to the ceiling is restricted to 2.75 m (9'-0"), load bearing walls of 25 cm (10') thick can be adopted up to four stories buildings, provided good bricks of 70 kg/cm strength are used with cement mortar as specified by the National Building Code;