Section 6.2.4/Exhaust Ventilation
ASHRAE 62.1 Section 6.2.4 and Table 6.2.4 specify minimum exhaust rates for restrooms, kitchens, and parking garages.
Table 6.2.4 specifies the minimum exhaust airflow rates for spaces where contaminants are generated and must be directly exhausted. Toilet rooms and bathrooms require exhaust at 50 cfm per water closet or urinal, or 0.5 cfm per square foot if the rate per fixture is not calculable. Commercial kitchens reference the hood exhaust requirements per ASHRAE 154 or the applicable mechanical code. Parking garages require 0.75 cfm per square foot for enclosed garages. Exhaust air from these spaces generally cannot be recirculated.
Why this section exists
Certain spaces generate concentrated contaminants that must be captured and removed at the source. General supply ventilation alone is insufficient to control odors from restrooms, grease from kitchens, or carbon monoxide from parking garages. Dedicated exhaust ensures these contaminants are removed before they migrate to adjacent occupied spaces.
What plan reviewers look for
Plan reviewers check the mechanical exhaust schedule against Table 6.2.4 for each space requiring exhaust. They verify the exhaust rate per fixture (restrooms) or per square foot (garages) and check that the exhaust system is shown on the mechanical drawings with the correct fan capacity and discharge location.
Common violations
Related ASHRAE 62.1 requirements
Section 6.2.1 covers the supply-side outdoor air rate. IMC Section 501 covers exhaust system requirements that parallel these rates. Section 5.7 covers exhaust discharge locations and separation from outdoor air intakes.