45.-(1) Every hoistway or liftway inside a building constructed after the coming into operation of this section shall, subject as hereafter in this subsection provided, be completely enclosed with fire-resisting materials, and all means of access to the hoist or lift shall be fitted with doors of fire-resisting materials:
Provided that any such hoistway or liftway shall be enclosed at the top only by some material easily broken by fire, or be provided with a vent at the top.
(2) Where in any factory more than twenty persons are employed in the same building, or explosive or highly inflammable materials are stored or used in any building in which persons are employed, effective provision shall be made for giving warning in case of fire, which shall be clearly audible throughout the building.