413.2 Attic, under-floor and concealed spaces.
BC § 413.2
Attic, under-floor and concealed spaces used for storage of combustible materials shall be protected on the storage side as required for 1-hour fire-resistance-rated construction. Openings shall be protected by assemblies that are self-closing and are of noncombustible construction or solid wood core not less than 1 3/4 inch (45 mm) in thickness. Exception: Neither fire-resistance-rated construction nor opening protectives are required in any of the following locations: 1. Areas protected by approved automatic sprinkler systems.
2.Group R-3 and U occupancies.
