R337.7.9 Underside of Appendages
When required by the enforcing agency the underside of overhanging appendages shall be enclosed to grade in accordance with the requirements of this chapter or the underside of the exposed underfloor shall consist of one of the following:
- Noncombustible material.
- Ignition-resistant material.
- One layer of 5/8-inch Type X gypsum sheathing applied behind an exterior covering on the underside of the floor projection.
- The exterior portion of a 1-hour fire resistive exterior wall assembly applied to the underside of the floor including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual.
- 5.1. SFM Standard 12-7A-3; or
- 5.2. ASTM E2957
Exception: Heavy-timber structural columns and beams do not require protection.