(a) Scope. This rule provides the construction requirements for masonry equivalent exit enclosures in Groups R-1, R-2 and B occupancies.
(b) References. See sections 1014.2.1 (Two exits and exit access doorways, Exceptions 3 and 4) and 1019.1 (Enclosures required Exception 10) of the building code.
(c) Stud wall construction requirements. A masonry equivalent exit enclosure constructed as stud and wall board assembly shall satisfy the following requirements:
(1) Prescriptive stud and wall board assembly. A compliant wall assembly shall be substantially identical to, and shall provide an impact resistance equivalent to or exceeding, the performance of one (1) of the following:
(i) Materials. Impact resistant wall board sheathed on the interior surface of the exit enclosure wall assembly shall be tested by an approved testing agency. The wall board used as the interior face panel shall be listed by an approved agency to ASTM C 1629-06, Standard Classification for Abuse-Resistant Nondecorated Interior Gypsum Panel Products and Fiber-Reinforced Cement Panels, Impact Classification Level 2, and the base layer panel shall be a minimum 5/8 inch (16 mm) gypsum wall board. Wall board applied to the interior surface of the exit enclosure wall shall not reduce the clear width of the exit stairs below that required for means of egress by Chapter 10 of the building code.
(ii) Assembly. The wall assembly shall be at least two-hour fire resistance rated.
(iii) Installation shall comply with the following:
(A) Studs shall be minimum 3-1/2 inch (89 mm) depth cold-formed steel framing, at least 33 mils thick (20 gauge).
(B) Vertical studs shall be spaced at a maximum distance of 24 inches (610 mm), on center.
(C) Runners shall be securely attached at the floor and ceiling to structural element members and shall comply with the structural requirements of the building code.
(D) Wall boards shall be attached with No. 8 self-drilling bugle-head screws, 12 inches (305 mm), on center maximum, with a minimum depth of 5/8 inch (16 mm) penetration into the wall cavity.
(E) Joints between adjoining sheets of wall board shall be staggered from base layer with face panel layer.
(2) Performance-based requirements. For a wall assembly not classified in subdivision (1) above, a masonry equivalent wall assembly shall satisfy the following requirements:
(i) Materials. Materials constituting the interior side of the exit enclosure wall assembly shall be tested by an approved testing agency to ASTM C1629, Hard Body Impact Classification Level 3.
(ii) Assembly. The wall assembly shall have a minimum two-hour fire resistance rating. The wall assembly shall be tested by an approved testing agency to ASTM C1629, Soft Body Impact Classification Level 2.
(iii) Installation. Wall assemblies shall be anchored to structural members and shall comply with the structural requirements of the building code.