3107.5 Construction.

3107.5 Construction.

3107.5.1 General. All signs shall be constructed of noncombustible materials except that approved plastics may be used in sign facings as described in Section 3107.5.2. All ferrous metal and all fastenings used in construction or installation, excluding stainless steel, shall be hot-dipped galvanized, porcelain-enameled or otherwise protected in an approved manner against corrosion.

Aluminum may only be used for minor internal members, such as stiffeners and closures, and for sign faces and nonstructural trim. The minimum thickness shall be 0.0299 inch (0.76 mm).

Steel shapes or plates used for primary support shall be not less than 3/16 inch (4.76 mm) in thickness. Sheet metal formed integrally with the sign face or used as cabinet cover shall be not less than 0.0239 inch (24 gauge). Secondary support members not formed integrally with the design face shall be not less than 0.1046 (12 gauge) inch.

The minimum material thickness requirements in this section pertain to the base metal before application of protective covering and need not apply to signs located inside a building.

3107.5.2 Plastics. Where plastics are included in a sign, the application to install a sign shall set forth the manufacturer’s trade name, or the common name of the plastic material to be used in the sign, thickness of plastic, aspect ratio, corrugation type, if any, and span. The plastic employed in the signs shall be identified as set forth in Chapter 26 with the manufacturer’s trade name, or with the common name of the plastic material.

Plastic sign facing shall conform to the provisions of this section. Plastic sign faces, formed or flat, letters and decorations shall be of sufficient thickness or so formed or supported that they will withstand all loads required by this code.

Plastic facing shall be mounted in a metal frame. Proper provision shall be made for the difference in thermal expansion between plastic members and the frame.

3107.5.3 Electric plastic signs. Every electric sign containing approved plastics shall comply with the minimum requirements set forth in the Standard for Electric Signs, UL No. 48. The attachment of Underwriters Laboratories label, or other approved laboratory per the Electrical Code, shall be sufficient proof that a sign has complied with the requirements of the Electrical Code.

3107.5.4 Wood-faced signs. Projecting signs with wood facing or backing are permitted on any building.

Plywood used for signs shall be exterior grade and not less than 5/8-inch (15.88 mm) thickness. Lumber shall be not less than 1-inch (25.4 mm) nominal and shall be finished to provide a weather- resistant finish.