Nothing in this chapter shall prevent the reconstruction, repairing, rebuilding and continued use of any nonconforming building or structure damaged by fire, collapse, explosion or act of God subsequent to the date of legal enactment of this chapter wherein the new restored building or structure is no greater than 150% the floor area of the existing building or structure at the time such damage occurred. The reconstruction of the destroyed or damaged buildings shall be initiated within one year of the date of damage.