Code of Massachusetts Regulations › 780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS › Chapter 9 - Fire Protection Systems › Section 909 - SMOKE CONTROL SYSTEMS › Subsection 909.5 - Smoke barrier construction

Current through Register 1525, July 5, 2024
Smoke barriers
shall comply with Section
				  710, and shall be constructed and sealed to limit leakage areas exclusive of
				  protected openings. The maximum allowable leakage area shall be the aggregate
				  area calculated using the following leakage area ratios: [F]
1. Walls:
A/A
w =
							 0.00100
2.
Exit
enclosures:
A/A
w =
							 0.00035
3. All other shafts:
A/A
w =
							 0.00150
4. Floors and roofs:
A/A
F =
							 0.00050
where:
A
= Total leakage area, square feet
				  (m2).
A
F= Unit floor or
				  roof area of barrier, square feet (m2).
A
w= Unit wall area
				  of barrier, square feet (m2).
The leakage area ratios shown do not include openings due to
				  doors, operable windows or similar gaps. These shall be included in calculating
				  the total leakage area.
909.5.1
Leakage area.
The total leakage area of the barrier is the product
				of the
smoke barrier
gross area multiplied by the allowable
				leakage area ratio, plus the area of other openings such as gaps and operable
				windows. Compliance shall be determined by achieving the minimum air pressure
				difference across the barrier with the system in the smoke control mode for
				mechanical smoke control systems. Passive smoke control systems tested using
				other
approved
means such as door fan testing shall be as
approved
by the fire code official. [F]
909.5.2
Opening protection.
Openings in
smoke barriers
shall be protected by
				automatic-closing devices actuated by the required controls for the mechanical
				smoke control system. Door openings shall be protected by
fire
				door
assemblies
complying with Section 715.4.3. [F]
Exceptions:
1. Passive smoke control systems with
				automatic-closing devices actuated by spot-type smoke detectors
listed
for releasing service installed in accordance with
				Section 907.3.
2. Fixed openings
				between smoke zones that are protected utilizing the airflow method.
3. In Group I-2, where such doors are
				installed across corridors, a pair of opposite-swinging doors without a center
				mullion shall be installed having vision panels with fire protection-rated
				glazing materials in fire protection-rated frames, the area of which shall not
				exceed that tested. The doors shall be close-fitting within operational
				tolerances and shall not have undercuts, louvers or grilles. The doors shall
				have head and jamb stops, astragals or rabbets at meeting edges and shall be
				automatic-closing by smoke detection in accordance with Section 715.4.8.3.
				Positive-latching devices are not required.
4. Group I-3.
5. Openings between smoke zones with clear
				ceiling heights of 14 feet (4267 mm) or greater and bank-down capacity of
				greater than 20 minutes as determined by the design fire size.
909.5.2.1
Ducts and air transfer
				openings.
Ducts and air transfer openings are required to be protected
				with a minimum Class II, 250°F (121°C)
smoke damper
complying with Section 716. [F]