It shall be the duty of the City Building Inspector, upon the filing of an application for a permit, to examine such plans and specifications, other data and the premises upon which it is proposed to erect or alter the sign. If it appears that the provisions of the sign regulations and all other laws and ordinances of the City are complied with, the City Building Inspector shall then issue the permit. If the work authorized by such permit is not completed in six (6) months from the date of its issuance, such permit shall become null and void.