Except as otherwise provided in Section 15.148.460 of this chapter all projecting signs must be double-faced except signs placed flat against a building or projecting V-shaped signs attached to a building at the open points of the V. Double-faced signs shall have a minimum of four inches and a maximum of twenty-four (24) inches between faces. The faces of such signs shall be fastened to an incombustible metal frame of such construction as to adequately support the sign faces. (Prior code § 3.05.083)