Outdoor air supply and exhaust openings shall be provided with Class IA motorized dampers with a maximum leakage rate of 4 cfm/ft2 (20.3 L/s • m2) at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA 500D.
1. Gravity (nonmotorized) dampers having a maximum leakage rate of 20 cfm/ft2 (101.6 L/s • m2) at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA 500D are permitted to be used as follows:
1.1. In buildings for exhaust and relief dampers.
1.2. In buildings less than three stories in height above grade.
1.3. For ventilation air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 1, 2 and 3.
1.4. Where the design outdoor air intake or exhaust capacity does not exceed 300 cfm (141 L/s).
Gravity (nonmotorized) dampers for ventilation air intakes shall be protected from direct exposure to wind.
2. Dampers smaller than 24 inches (610 mm) in either dimension shall be permitted to have a leakage of 40 cfm/ft2 (203.2 L/s • m2) at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA 500D.