It shall be unlawful to use or permit the use of any building or premises or part thereof, hereafter created, erected, changed, converted or enlarged, wholly or partly, in its use or structure, until a certificate of occupancy shall have been issued by the Board of Trustees or the administrative official, as the case may be. Said certificate shall show that said building, structure or premises or part thereof and the proposed uses thereof are in conformity with the provisions of this chapter. It shall be the duty of the Board of Trustees or the administrative official, as the case may be, to issue a certificate of occupancy within 10 days after a request for the same shall be filed in his office by the owner of a building or premises, provided that said building or premises or part thereof, and the proposed use thereof, conform to the requirements herein set forth.