No building or portion thereof which has been totally or partially destroyed or damaged by fire, action of the elements or any other cause, prior to the effective date of this chapter, where the use for which such building was erected or to which it was put prior to such destruction or damage is forbidden by any provision by law, statute or ordinance by reason of such destruction or damage or has been discontinued by the owner, occupant or lessee thereof, and the reconstruction, restoration or repair of such building has not been commenced on or prior to the effective date of this chapter, shall be permitted to remain in any zoning district more than 30 days after the effective date of this chapter unless all necessary building and/or other permits are obtained for and the reconstruction, restoration or repair of such building is commenced within 60 days of such destruction and fully completed within six months thereafter.