Mechanical exhaust systems shall be sized to remove the quantity of air required by this article to be exhausted. The system shall operate when air is required to be exhausted. Where mechanical exhaust is required in a room or space in occupancies other than in Groups R-3, R-4 and R-5 and dwelling units in Group R-2, such space shall be maintained with a neutral or negative pressure. If a greater quantity of air is supplied by a mechanical ventilating supply system than is removed by a mechanical exhaust system for a room, adequate means shall be provided for the natural or mechanical exhaust of the excess air supplied. If only a mechanical exhaust system is installed for a room or if a greater quantity of air is removed by a mechanical exhaust system than is supplied by a mechanical ventilating supply system for a room, adequate means shall be provided for the natural supply of the deficiency in the air supplied.
(Amend Coun. J. 9-14-21, p. 35949, Art. V, § 1)