The advertising surface shall be of metal, or other incombustible materials, and the supporting frame shall be made of galvanized metal, except that footings may be of black iron, well painted to prevent corrosion, or timber, or of reinforced concrete or masonry; provided, that roof signs having a total height of four feet or less above the roof of one story buildings may be constructed entirely of approved combustible materials. Ornamental molding, battens, nailing strips and decorative trimmings may be of approved combustible materials. (Ord. 89-3 (part), 1989)