Section 78(2)(b) in The Punjab Factory Rules, 1952
(b)The height of every room in the building shall be not less than 3.65 metre from floor level to the lowest Part of the roof and there shall be at least 1.1 sq.m. of floor area for every person employed. Provided that (i) workers who habitually go home for their meals during the rest periods may be excluded in calculating number of workers to be accommodated (ii) in the case of factories in existence at the date of commencement of the Act, where it is impracticable owing to lack of space to provide 1.1 square metre of floor area for each person, such reduced floor area per person shall be provided as may be approved in writing by the Chief Inspector.