17.36.110   Material requirements.
   Materials of construction for signs and sign structures shall be of the quality and grade as specified for building in the Uniform Sign Code, as from time to time adopted.
   A.   Restrictions and Combustible Materials. All signs and sign structures erected in the business district shall have structural members of heavy timber construction as defined in the Uniform Building Code, as from time to time amended, or of incombustible materials. Ground signs may be constructed of any material meeting the requirements of this chapter, except as provided above. Combination signs, roof signs, wall signs, projecting signs, and signs on marquees shall be constructed of incombustible materials, except as provided in subsection B of this section. No combustible materials other than approved plastics shall be used in the construction of electric signs.
   B.   Nonstructural Trim. Nonstructural trim may be made of wood, metal, approved plastics or any combination thereof. The nonstructural trim may not exceed ten percent of the total area of the sign.
   C.   Fastenings. Signs attached to masonry, concrete or steel shall be safely and securely fastened thereto by means of metal anchors, bolts or approved expansion screws or sufficient size and anchorage to support safely the loads applied. All building fastenings must be of galvanized or noncorrosive materials.
(Ord. 441 Art. VI § 14, 1992).