A nonconforming building damaged or destroyed by fire, explosion, earthquake or other act to an extent of more than 75% of the appraised value thereof, according to either the assessor's records or an appraisal performed by a qualified real estate appraiser may be restored only if made to conform to all the regulations of the district in which it is located, provided that such building may be restored to a floor area not exceeding that of the former building if a use permit first shall be secured.
(`67 Code, § 10-14-6)