718.4.2 Groups R-1 and R-2.
BC § 718.4.2
Draftstopping shall be provided in attics, mansards, overhangs or other concealed roof spaces of Group R-2 buildings with three or more dwelling units and in all Group R-1 buildings. Draftstopping shall be installed above, and in line with, dwelling unit separation walls that do not extend to the underside of the roof sheathing above. Exceptions: 1. Draftstopping shall not be required where the structural members within the concealed attic space are individually protected on all sides for their full length with materials having the required fire-resistance rating.
2.Draftstopping is not required in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.
3.In occupancies in Group R-2 that do not exceed four stories above grade plane, the attic space shall be subdivided by draftstops into areas not exceeding 3,000 square feet (278.7 m 2 ) or above every two dwelling units, whichever is smaller.
4.Draftstopping is not required in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.2, provided that automatic sprinklers are installed in the combustible concealed space where the draftstopping is being omitted.
5.Where laminated wood I-joist assemblies are used, the space between the ceiling and the floor or roof above shall be divided into approximately equal areas not greater than 500 square feet (46.5 m 2 ).
