508.5 Hood Size — 2025 California Mechanical Code

Hoods shall be sized in accordance with

the airflow capacity in accordance with Section 508.5.1.1 and installed to provide for the removal of heat, and capture and removal of grease-laden vapors in accordance with Section 511.2.2.

508.5.1 Canopy Size and Location. For canopy type commercial cooking hoods, the inside edge thereof shall overhang or extend a horizontal distance of not less than 6 inches (152 mm) beyond the edge of the cooking surface on open sides, and the vertical distance between the lip of the hood and the cooking surface shall not exceed 4 feet (1219 mm).

Exception: Listed exhaust hoods are to be installed in accordance with the terms of their listings and the manufacturer’s installation instructions.

508.5.1.1 Capacity of Hoods. Canopy-type commercial cooking hoods shall exhaust through the hood with a quantity of air not less than determined by the application in accordance with Section 508.5.1.2 through Section 508.5.1.5. The exhaust quantity shall be the net exhaust from the hood determined in accordance with Equation 508.5.1.1. The duty level for the hood shall be the duty level of the appliance that has the highest (heaviest) duty level of appliances installed underneath the hood.

Exception: Listed exhaust hoods installed in accordance with the manufacturer’s installation instruc tions.

E NET = E HOOD – MA ID (Equation 508.5.1.1)

112 2025 CALIFORNIA MECHANICAL CODE

EXHAUST SYSTEMS

Where:

E NET = net hood exhaust, CFM.

E HOOD = total hood exhaust, CFM.

MA ID = makeup air, internal discharge, CFM.

For SI Units: 1 cubic foot per minute = 0.4719 L/s

508.5.1.2 Extra-Heavy-Duty Cooking Appli- ances. The minimum net airflow for hoods used for

solid fuel cooking appliances such as charcoal, briquette, and mesquite to provide the heat source for cooking shall be in accordance with Table 508.5.1.2.

TABLE 508.5.1.2

EXTRA-HEAVY-DUTY COOKING APPLIANCE AIRFLOW

For SI units: 1 foot = 304.8 mm, 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s

508.5.1.3 Heavy-Duty Cooking Appliances. The minimum net airflow for hoods used for cook ing appliances such as gas under-fired broilers, gas chain (conveyor) broilers, electric and gas wok ranges, and electric and gas over-fired (upright) broilers shall be in accordance with Table 508.5.1.3.

TABLE 508.5.1.3

HEAVY-DUTY COOKING APPLIANCE AIRFLOW

For SI units: 1 foot = 304.8 mm, 1 cubic foot per minute = 0.0283 m [3] /min,

1 cubic foot per minute = 0.4719 L/s

508.5.1.4 Medium-Duty Cooking Appliances. The minimum net airflow for hoods used for cooking appliances such as electric and gas hot-top ranges, gas open-burner ranges (with or without oven), elec

TABLE 508.5.1.5

LIGHT-DUTY COOKING APPLIANCE AIRFLOW

For SI units: 1 foot = 304.8 mm, 1 cubic foot per minute = 0.0283 m [3] /min,

1 cubic foot per minute = 0.4719 L/s

508.5.2 Noncanopy-Type Hoods. Noncanopy-type commercial cooking hoods shall be installed and sized in accordance with the manufacturer’s installation instruc tions, and Section 508.5.2.1 and Section 508.5.2.2.

Exception: Listed hood assemblies designed and installed specifically for the intended use.

tric and gas flat griddles, electric and gas doublesided griddles, electric and gas fryers (including open deep fat fryers, donut fryers, kettle fryers, tortilla chip fryers, and pressure fryers), electric and gas smokers, and electric and gas conveyor pizza ovens shall be in accordance with Table 508.5.1.4.

TABLE 508.5.1.4

MEDIUM-DUTY COOKING APPLIANCE AIRFLOW

For SI units: 1 foot = 304.8 mm, 1 cubic foot per minute = 0.0283 m [3] /min,

508.5.1.5 Light-Duty Cooking Appliances. The minimum net airflow for hoods used for cooking appliances such as gas and electric ovens (including standard, bake, roasting, revolving, retherm, convection, combination convection/steamer, rotisserie, countertop conveyorized baking/finishing, deck, and pastry), discrete element ranges (with or without oven), electric and gas steam-jacketed kettles less than 20 gallons (76 L), electric and gas pasta cookers, electric and gas compartment steamers (both pressure and atmospheric), electric and gas cheese melters, electric and gas tilting skillets (braising pans) electric and gas rotisseries, and electric and gas salamanders shall be in accordance with Table 508.5.1.5.

TABLE 508.5.1.4

MEDIUM-DUTY COOKING APPLIANCE AIRFLOW

For SI units: 1 foot = 304.8 mm, 1 cubic foot per minute = 0.0283 m [3] /min,

1 cubic foot per minute = 0.4719 L/s

EXHAUST SYSTEMS

508.5.2.1 Installation. Noncanopy-type commercial cooking hoods shall be installed with the edge of the hood set back not more than 1 foot (305 mm) from the edge of the cooking surface, and the vertical distance between the lip of the hood and the cooking surface shall not exceed 3 feet (914 mm). 508.5.2.2 Capacity. In addition to other requirements for hoods specified in this section, the volume of air exhausting through a noncanopy-type hood to the duct system shall be not less than 300 cubic feet per minute per lineal foot [(ft [3] /min)/ft)] [0.464 (m [3] /s)/m] of cooking equipment. Listed noncanopy exhaust hoods and filters shall be sized and installed in accordance with the terms of their listing and the manufacturer’s installation instructions.

508.5.3 Labeling. Type I hoods shall bear a label indicating the exhaust flow rate in cubic feet per minute per lineal foot [(m [3] /s)/m].