The materials prescribed herein for ignition resistance shall conform to the requirements of this chapter.
Ignition-resistant materials shall comply with one of the following:
A material shall comply with the conditions of acceptance in Items 1 and 2 below when the test is continued for an additional 20-minute period, meaning for a total test period of an “extended” 30-minute test period.
- The material shall exhibit a flame spread index not exceeding 25 and shall show no evidence of progressive combustion following the extended 30-minute test period.
- The material shall exhibit a flame front that does not progress more than 101 /2 feet (3200 mm) beyond the centerline of the burner at any time during the extended 30-minute test period.
Any one of the following shall be accepted as meeting the definition of ignition-resistant material:
- Noncombustible material. Material that complies with the definition for noncombustible materials in Section 202.
- Fire-retardant-treated wood. Fire-retardant-treated wood identified for exterior use that complies with the requirements of Section 2303.2.
- Fire-retardant-treated wood shingles and shakes. Fire-retardant-treated wood shingles and shakes, as defined in Section 1505.6 and listed by State Fire Marshal for use as “Class B” roof covering, shall be accepted as an ignition-resistant wall covering material when installed over solid sheathing.