- The Commissioner may, at any time during the erection of a building or the execution of any such work as aforesaid, or at any time within three months after the completion thereof, by written notice, specify any matter in respect of which the erection of such building or the execution of such work may be in contravention of any provision of this Act or of any bye-law made under this Act at the time in force, and require the person erecting or executing or who has erected or executed such building or work, or, if the person who has erected or executed such building or work is not at the time of the notice the owner thereof, then the owner of such building or work, to cause anything done contrary to any such provision or bye-law to be amended or to do anything which by any such provision or bye-law may be required to be done but which has been omitted to be done.