Where no substantial work is done under a permit within ninety days of its issuance it shall become null and void.
Permits issued under the terms of this article convey no right to erect any building other than mobile homes or to do any plumbing work or to do any electrical work. Regular building, plumbing, electrical or other permits as required by the provisions of the ordinances of the City shall be secured for all such work.
(1960 Code 7-324)