In combustible construction, fireblocking shall be provided to cut off both vertical and horizontal concealed draft openings and to form an effective fire barrier between stories, and between a top story and the roof space.
Fireblocking shall be provided in wood-framed construction in the following locations:
- 1.1. Vertically at the ceiling and floor levels.
- 1.2. Horizontally at intervals not exceeding 10 feet (3048 mm).
- At interconnections between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings and cove ceilings.
- In concealed spaces between stair stringers at the top and bottom of the run. Enclosed spaces under stairs shall comply with Section R302.7.
- At openings around vents, pipes, ducts, cables and wires at ceiling and floor level, with an approved material to resist the free passage of flame and products of combustion. The material filling this annular space shall not be required to meet the ASTM E136 requirements.
- For the fireblocking of chimneys and fireplaces, see Section R1003.19.
- Fireblocking of cornices of a two-family dwelling is required at the line of dwelling unit separation.
- Two-inch (51 mm) nominal lumber.
- Two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints.
- One thickness of 23/32-inch (18.3 mm) wood structural panels with joints backed by 23/32-inch (18.3 mm) wood structural panels.
- One thickness of 3/4-inch (19.1 mm) particleboard with joints backed by 3/4-inch (19.1 mm) particleboard.
- One-half-inch (12.7 mm) gypsum board.
- One-quarter-inch (6.4 mm) cement-based millboard.
- Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place.
- Cellulose insulation installed as tested in accordance with ASTM E119 or UL 263, for the specific application.