The Ontario Building Code | Exhaust Duct Negative Pressure

3.6.3.4. Exhaust Duct Negative pressure

(1) If a vertical service space contains an exhaust duct that serves more than one fire compartment, the duct shall have a fan located at or near the exhaust outlet to ensure that the duct is under negative pressure.

3.6.4. Horizontal service Spaces and service Facilities