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906.1 When Required. Smoke and heat vents complying with U.B.C. Standard 15-7 or fixed openings shall be installed in accordance with the provisions of this section as follows:

1. In single-story Groups B, F, M and S Occupancies having over 50,000 square feet (4645 ) in undivided area.

EXCEPTIONS: 1. Office buildings and retail sales areas where storage does not exceed 12 feet (3658 mm) in height.

2. Group S, Division 2 Occupancies used for bulk frozen food storage when the building is protected by a complete automatic sprinkler system.

2. In Group H, Divisions 1, 2, 3, 4 or 5 Occupancies any of which are over 15,000 square feet (1394 ) in single floor area.

For requirements on smoke and heat venting in buildings with high-piled combustible stock, see the Fire Code.

906.2 Mixed Occupancies. Venting facilities shall be installed in buildings of mixed occupancy on the basis of the individual occupancy involved.

906.3 Types of Vents. Vents shall be fixed in the open position or vents shall be activated by temperature and shall open automatically in the event of fire.

Fixed openings may consist of skylights or other openings which provide venting directly to exterior above the plane of the main roof in which they are located. Vents shall meet the design criteria of this subsection regarding elevation, and Section 906.5 of this section regarding venting area, dimensions, spacing and venting ratios. The building official may require documentation of the design to assure proper performance of required venting.

Temperature activation of vents shall be at or near the highest elevation of the ceiling and in no case lower than the upper one third of the smoke curtain. Where plain glass is used, provisions shall be made to protect the occupants from glass breakage. In no case shall vents be located closer than 20 feet (6096 mm) to an adjacent property line.

906.4 Releasing Devices. Release devices shall be in accordance with U.B.C. Standard 15-7.

906.5 Size and Spacing of Vents.

906.5.1 Effective venting area. The effective venting area is the minimum cross-sectional area through which the hot gases must pass en route to atmosphere. The effective venting area shall not be less than 16 square feet (1.5 ) with no dimension less than 4 feet (1219 mm), excluding ribs or gutters whose total width does not exceed 6 inches (152 mm).

906.5.2 Spacing. The maximum center-to-center spacing between vents within the building shall be:

1. In Groups B, F, M and S Occupancies: 120 feet (36 600 mm).

2. In Group H Occupancies: 100 feet (30 480 mm).

906.5.3 Venting ratios. The following ratios of effective area of vent openings to floor areas shall be:

1. In Groups B, F, M and S Occupancies: 1:100.

2. In Group H Occupancies: 1:50.

906.6 Curtain Boards.

906.6.1 General. Curtain boards shall be provided to subdivide a vented building in accordance with the provisions of this section.

906.6.2 Construction. Curtain boards shall be sheet metal, asbestos board, lath and plaster, gypsum wallboard or other approved materials which provide equivalent performance that will resist the passage of smoke. All joints and connections shall be smoke tight.

906.6.3 Location and depth. Curtain boards shall extend down from the ceiling for a minimum depth of 6 feet (1829 mm), but need not extend closer than 8 feet (2436 mm) to the floor. In Group H Occupancies, the minimum depth shall be 12 feet (3660 mm) except that it need not be closer than8 feet (2436 mm) to the floor, provided the curtain is not less than 6 feet (1829 mm) in depth.

906.6.4 Spacing. The distance between curtain boards shall not exceed 250 feet (76 200 mm) and the curtained area shall be limited to 50,000 square feet (4645 ). In Group H Occupancies, the distance between curtain boards shall not exceed 100 feet (30 480 mm) and the curtained area shall be limited to 15,000 square feet (1394 ).

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