(1) After a certificate has been granted it is lawful for the Chief Fire Officer to cause at any time any industrial and commercial building and every part of it to be examined for the purpose of ascertaining whether the existing means of escape are maintained or whether there is a change of conditions by reason of which the existing means of escape in case of fire are insufficient.
(2) If after a certificate has been granted, it is proposed to make any material extension or material structural alteration of an industrial or commercial building or any part of it or to increase the number of persons employed in that building or in any part specified in the certificate, or to begin to store or use explosive, highly inflammable or combustible material in that building or materially to increase the extent of such storage or use, the owner shall give notice in writing of the proposal to the Chief Fire Officer.
(3) If at any time the Chief Fire Officer is satisfied that by reason of the changed conditions the existing means of escape have become insufficient or if on receipt of the notice under subsection (2) he or she is of opinion that the conditions in regard to escape in case of fire will be affected, he or she may by notice in writing require the owner to make the alterations specified in the notice, within such time as may be specified in the notice and subject to the provisions of section 15 the owner shall carry out such alterations within such time as may be specified therein.