In each case, openings into fire-resistance-rated construction shall be limited to those needed for maintenance and operation and shall be protected by self-closing fire-resistance-rated devices in accordance with the International Building Code for enclosure wall opening protectives. Exit enclosure ventilation systems shall be independent of other building ventilation systems.
The use of gypsum boards to form plenums shall be limited to systems where the air temperatures do not exceed 125°F (52°C) and the building and mechanical system design conditions are such that the gypsum board surface temperature will be maintained above the airstream dew-point temperature. Air plenums formed by gypsum boards shall not be incorporated in air-handling systems utilizing evaporative coolers.
The foam plastic insulation shall be approved based on tests conducted in accordance with Section 2603.10 of the International Building Code.
|DUCT SIZE||GALVANIZED||ALUMINUM |
MINIMUM THICKNESS (in.)
|Minimum thickness (in.)||Equivalent galvanized gage no.|
|Round ducts and enclosed rectangular ducts |
14 inches or less
16 and 18 inches
20 inches and over
|Exposed rectangular ducts |
14 inches or less
Over 14 inchesa
Exception: Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion so as to prevent a hinge effect.
Exception: Dwelling units.
Exception: Smoke detectors are not required in the return air system where all portions of the building served by the air distribution system are protected by area smoke detectors connected to a fire alarm system in accordance with the International Fire Code. The area smoke detection system shall comply with Section 606.4.
Exception: Individual smoke detectors shall not be required for each fan-powered terminal unit, provided that such units do not have an individual design capacity greater than 2,000 cfm (0.9 m3/s) and will be shut down by activation of one of the following:
FIRE DAMPER RATING
|TYPE OF PENETRATION||MINIMUM |
|Less than 3-hour fire-resistance-rated assemblies||11/2|
|3-hour or greater fire-resistance-rated assemblies||3|
Exception: Fire dampers are not required at penetrations of fire barriers where any of the following apply:
Exception: In occupancies other than Group H, fire dampers are not required where any of the following apply:
- Smoke dampers are not required in corridor penetrations where the building is equipped throughout with an approved smoke control system in accordance with Section 513 and smoke dampers are not necessary for the operation and control of the system.
- Smoke dampers are not required in smoke barrier penetrations where the openings in ducts are limited to a single smoke compartment and the ducts are constructed of steel.
- Smoke dampers are not required in corridor penetrations where the duct is constructed of steel not less than 0.019 inch (0.48 mm) in thickness and there are no openings serving the corridor.
- Smoke dampers are not required in ducted corridor
- The building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 of the Building Code;
- The duct is constructed of steel not less than 0.019 inch (0.48 mm) in thickness;
- The ducted system supplies outdoor air only to the corridor and to air-handling units that serve spaces adjoining the corridor through ducted connections; and
- The outdoor air supply fan is designed to provide a continuous airflow.
- Fire and smoke dampers are not required at penetrations of exhaust shafts where steel exhaust subducts extend at least 22 inches (559 mm) vertically in exhaust shafts provided there is a continuous airflow upward to the outside and the fan is provided with backup standby power.
- Fire dampers are not required where penetrations are tested in accordance with ASTM E 119 or UL 263 as part of the fire-resistance-rated assembly.
- Fire and smoke dampers are not required where ducts are used as part of an approved smoke control system in accordance with Section 909 of the Building Code.
- Fire and smoke dampers are not required where the penetrations are in dedicated parking garage exhaust or supply shafts that are separated from other building shafts by not less than 2-hour fire-resistance-rated construction.
- Smoke dampers are not required at penetrations of shafts where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 of the Building Code.
- Fire dampers and combination fire/smoke dampers are not required in kitchens and clothes dryer exhaust systems installed in accordance with the Mechanical Code.
Exception: A duct is permitted to penetrate three floors or less without a fire damper at each floor provided it meets all of the following requirements.
Exception: Fire dampers are not required in ducts within individual residential dwelling units.