Household cooking appliances shall have a vertical clearance above the cooking top of not less than 30 inches (760 mm) to combustible material or metal cabinets. A minimum clearance of 24 inches (610 mm) is permitted when one of the following is installed:
1. The underside of the combustible material or metal cabinet above the caulking top is protected with not less than 1/4 inch(6 mm) insulating miliboard covered with sheet metal not less than 0.0122 inch (0.3 mm)
2. A metal ventilating hood of sheet metal not less than 0.0122 inch (0.3 mm) thick is installed above the cooking top with a clearance of not less than 1/4 inch (6 mm) between the hood and the underside of the combustible material or metal cabinet, and the hood is at least as wide as the appliance and is centered over the appliance.
3. A listed cooking appliance or microwave oven is installed over a listed cooking appliance and will conform to the terms of the upper appliance's listing and the manufacturers' instructions.