In the event that any act required by this chapter or by an ordinance enacted pursuant to Section 13.12.030 cannot be performed within the time herein provided on account of shortages of materials, war, restraint by public authorities, strikes, labor disturbances, or any other circumstances beyond the control of the parties, then the time within which such act will be accomplished shall be extended for a period equivalent to the time of such Limitation. (Prior code § 8400.10)