“Ordinary maintenance and repair” means any work for which a building permit is not required by law, where the purpose and effect of such work is to correct any deterioration or decay of or damage to a structure or any part thereof or to restore the same, as nearly as may be practicable, to its condition prior to the occurrence of such deterioration, decay or damage, and which work, in the judgment of the Building Official, does not substantially alter the appearance, composition, or texture of the exterior surface of the structure or sign.