A permit issued pursuant to § 150.25 shall expire by limitation six months, or any lesser time fixed by ordinance of the City Council, after the date of issuance if the work authorized by the permit has not been commenced. If after commencement the work is discontinued for a period of 12 months, the permit therefor shall immediately expire. No work authorized by any permit that has expired shall thereafter be performed until a new permit has been secured.
(G.S. § 160A-418)