The following revision is made to Section M1503.6 Make Up Air Required of the International Residential Code: M1503.6. Makeup air required. Exhaust hood systems capable of exhausting more than 400 cubic feet per minute (0.19m 3 /s) shall be mechanically or naturally provided with makeup air at a rate approximately equal to the exhaust air rate in excess of 400 cubic feet per minute. Such makeup air systems shall be equipped with not less than one damper. Each damper shall be a gravity damper or an electrically operated damper that automatically opens when the exhaust system operates. Dampers shall be accessible for inspection, service, repair and replacement without removing permanent construction or any other ducts not connected to the damper being inspected, serviced, repaired or replaced.