508.5 Hood Size. Hoods shall be sized in accordance with
California Mechanical Code (Title 24, Part 4) · 2022 edition · updated 2026-09-10 · California
Italicized text is a California amendment to the model code, as printed in the official publication.
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 instructions.
ENET = EHOOD - MAID (Equation 508.5.1.1)
Where: ENET = net hood exhaust EHOOD = total hood exhaust MAID = makeup air, internal discharge
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
| TYPE OF HOOD | AIRFLOW (cubic foot per minute per linear foot of hood) |
|---|---|
Backshelf/pass-over |
Not permitted |
Double island canopy (per side) |
550 |
Eyebrow |
Not permitted |
Single island canopy |
700 |
Wall-mounted canopy |
550 |
For SI units: 1 cubic foot per minute = 0.00047 m 3 /s, 1 foot = 304.8 mm
508.5.1.3 Heavy-Duty Cooking Appliances. The minimum net airflow for hoods used for cooking 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
| TYPE OF HOOD | AIRFLOW (cubic foot per minute per linear foot of hood) |
|---|---|
Backshelf/pass-over |
400 |
Double island canopy (per side) |
400 |
Eyebrow |
Not permitted |
Single island canopy |
600 |
Wall-mounted canopy |
400 |
For SI units: 1 cubic foot per minute = 0.00047 m 3 /s, 1 foot = 304.8 mm
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), electric and gas flat griddles, electric and gas doublesided griddles, electric and gas fryers (including open deep fat fryers, donut fryers, kettle fryers, and pressure fryers), 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
| TYPE OF HOOD | AIRFLOW (cubic foot per minute per linear foot of hood) |
|---|---|
Backshelf/pass-over |
300 |
Double island canopy (per side) |
300 |
Eyebrow |
250 |
Single island canopy |
500 |
Wall-mounted canopy |
300 |
For SI units: 1 cubic foot per minute = 0.00047 m 3 /s, 1 foot = 304.8 mm
100 2022 CALIFORNIA MECHANICAL CODE
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 508.5.1.5 LIGHT-DUTY COOKING APPLIANCE AIRFLOW
| TYPE OF HOOD | AIRFLOW (cubic foot per minute per linear foot of hood) |
|---|---|
Backshelf/pass-over |
250 |
Double island canopy (per side) |
250 |
Eyebrow |
250 |
Single island canopy |
400 |
Wall-mounted canopy |
200 |
For SI units: 1 cubic foot per minute = 0.00047 m 3 /s, 1 foot = 304.8 mm
508.5.2 Noncanopy-Type Hoods. Noncanopy-type commercial cooking hoods shall be installed and sized in accordance with the manufacturer’s installation instructions, and Section 508.5.2.1 and Section 508.5.2.2. Exception: Listed hood assemblies designed and installed specifically for the intended use.
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].
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Ask AI about this code▸Contents — California Mechanical Code (Title 24, Part 4)
- Chapter 1 — GENERAL CODE PROVISIONS
- Chapter 2 — DEFINITIONS
- Chapter 3 — GENERAL REGULATIONS
- Chapter 4 — VENTILATION AIR
▸Chapter 5 — EXHAUST SYSTEMS
Overview- 501.1 Applicability. This chapter includes requirements for
- 502.1 Exhaust Opening Protection. Exhaust openings
- 502.2 Termination of Exhaust Ducts. Exhaust ducts
- 503.1 General. Motors and fans shall be sized to provide
- 503.2 Fans. Parts of fans in contact with explosive or flammab…
- 504.1 General. Where not specified in this chapter, exhaust
- 504.2 Independent Exhaust Systems. Single or combined mechanic…
- 504.3 Domestic Range. Ducts used for domestic kitchen
- 504.4 Clothes Dryers. A clothes dryer exhaust duct shall not
- 504.5 Heat (Energy) Recovery Ventilators. Heat
- 504.6 Gypsum Wallboard Ducts. Bathroom and laundry
- 505.1 General. A mechanical ventilation or exhaust system
- 505.2 Incompatible Materials. Incompatible materials
- 505.3 Flammability Limit. Unless the circumstances stipulated …
- 505.4 Air-Moving Devices. Air-moving devices shall be
- 505.5 Generating Flames, Sparks, or Hot Materials.
- 505.6 Fire Dampers. Fire dampers shall be permitted to be
- 505.7 Fire Detection and Alarm Systems. Unless the
- 505.8 Product-Conveying Ducts Classification. Product-conveyin…
- 505.9 Minimum Velocities and Circulation. The velocity and cir…
- 505.10 Makeup Air. Makeup air shall be provided to replenish a…
- 505.11 Hoods and Enclosures. Hoods and enclosures shall
- 505.12 Pharmacies – Compounding Area of Par-
- 506.1 Materials. Materials used in product-conveying duct
- 506.2 Construction. Ducts used for conveying products
- 506.3 Penetrations. Exhaust ducts shall not pass through
- 506.4 Condensate. Joints in duct construction shall be liquidt…
- 506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be
- 506.6 Explosion Venting. Ducts conveying explosive dusts
- 506.7 Supports. Supports shall be of noncombustible materials,…
- 506.8 Fire Protection. Sprinklers or other fire-protection
- 506.9 Protection from Physical Damage. Ducts
- 506.10 Duct Clearances. Unless the conditions stipulated
- 506.11 Clearance Reduction Methods. It shall be permitted to p…
- 507.1 Type I Hood Exhaust System. Exhaust systems
- 507.2 Exhaust System. Cooking equipment used in
- 507.3 Listed Devices. Penetrations shall be sealed with
- 507.4 Clearance. Where enclosures are not required, hoods,
- 507.5 Drawings. A drawing(s) of the exhaust system installatio…
- 507.6 Notification of Change. If required by the Authority Hav…
- 507.7 Pharmaceutical Compounding Exhaust Dis-
- 508.1 Where Required. Type I hoods shall be installed at
- 508.2 Listed Type I Hood Assemblies. Listed hood
- 508.3 Construction of Type I Hoods. The hood or that
- 508.4 Supports. Hoods shall be secured in place [OSHPD
- 508.5 Hood Size. Hoods shall be sized in accordance with
- 508.6 Solid-Fuel Hood Assemblies. Where solid-fuel
- 508.7 Exhaust Outlets. An exhaust outlet within an
- 509.1 Grease Removal Devices. Listed grease filters or
- 509.2 Installation. The distance between the grease removal
- 509.3 Solid-Fuel Grease Removal Devices. Where
- 510.1 General. Ducts shall not pass through fire walls.
- 510.2 Clearance. Clearance between ducts and combustible
- 510.3 Openings. Openings shall be provided at the sides or
- 510.4 Listed Grease Ducts. Listed grease ducts shall be
- 510.5 Other Grease Ducts. Other grease ducts shall comply with…
- 510.6 Exterior Installations. The exterior portion of the
- 510.7 Interior Installations. In all buildings more than one
- 510.8 Underground Installations. Grease ducts installed
- 510.9 Termination of Type I Hood Exhaust System.
- 510.10 Solid-Fuel Duct Systems. Where solid-fuel cooking equip…
- 511.1 Exhaust Fans for Commercial Cooking Opera-
- 511.2 Airflow. The air velocity through a duct shall be not
- 511.3 Makeup Air. The makeup air quantity shall prevent
- 511.4 Common Duct (Manifold) Systems. Master
- 511.5 Solid-Fuel Air Movement Requirements. Where
- 512.1 Dampers. Dampers shall not be installed in exhaust
- 512.2 Electrical Equipment. Wiring systems of any type
- 512.3 Other Equipment. Fume incinerators, thermal recovery uni…
- 512.4 Solid-Fuel Auxiliary Equipment. Where solid fuel
- 513.1 General. Fire-extinguishing equipment for the protection…
- 513.2 Types of Equipment. Fire-extinguishing equipment
- 513.3 Simultaneous Operation. Fixed pipe extinguishing
- 513.4 Fuel and Electric Power Shutoff. Upon activation of
- 513.5 Manual Activation. All systems shall have both automatic…
- 514.2 Inspection, Testing, and Maintenance. Maintenance of the…
- 513.6 System Annunciation. Upon activation of an automatic fir…
- 513.7 Special Design and Application. Hoods containing
- 513.8 Review and Certification. Where required, complete
- 513.9 Installation Requirements. Installation of systems
- 513.10 Portable Fire Extinguishers. Portable fire extinguisher…
- 513.11 Maintenance. Portable fire extinguishers shall be
- 513.12 Solid-Fuel Fire-Extinguishing Equipment.
- 514.1 Operating Procedures. Exhaust systems shall be
- 514.3 Inspection for Grease Buildup. The entire exhaust
- 514.4 Cleaning of Exhaust Systems. If, upon inspection,
- 514.5 Cooking Equipment Maintenance. Inspection and
- 515.1 Cooking Equipment. Cooking equipment shall be
- 515.2 Operating Controls. Deep-fat fryers shall be equipped
- 516.1 General Requirements. Recirculating systems containing o…
- 516.2 Design Restrictions. All recirculating systems shall
- 516.3 Interlocks. The recirculating system shall be provided
- 516.4 Location and Application Restrictions. The
- 516.5 Additional Fire Safety Requirements. In addition to the …
- 516.6 Use and Maintenance. Automatic or manual covers on cooki…
- 517.1 Venting Application. Venting requirements of solidfuel c…
- 517.2 Location of Appliances. Every appliance shall be
- 517.3 Hoods for Solid-Fuel Cooking. Hoods shall be sized
- 517.4 Exhaust Systems for Solid-Fuel Cooking. Where
- 517.5 Grease Removal Devices for Solid-Fuel Cook-
- 517.6 Air Movement for Solid-Fuel Cooking. Exhaust
- 517.7 Fire-Extinguishing Equipment for Solid-Fuel
- 517.8 Other Safety Requirements. Metal-fabricated solidfuel co…
- 518.1 General. Downdraft appliance ventilation system
- 518.2 Ventilation System. The downdraft appliance ventilation …
- 518.3 Fire-Extinguishing Equipment. For fire-extinguishing equ…
- 518.4 Airflow Switch or Transducer. An airflow switch or
- 518.5 Surface Materials. Any surface located directly
- 519.1 Where Required. Type II hoods shall be installed
- 519.2 Construction of Type II Hoods. Type II hoods
- 519.3 Dishwashing Appliances. The net airflow for Type
- 519.4 Type II Exhaust Duct Systems. Ducts and
- 519.5 Termination of Type II Hood Exhaust System.
- 519.6 Makeup Air. Makeup air shall be provided in accordance w…
- Chapter 6 — DUCT SYSTEMS
- Chapter 7 — COMBUSTION AIR
- Chapter 8 — CHIMNEYS AND VENTS
- Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
- Chapter 10 — BOILERS AND PRESSURE VESSELS
- Chapter 11 — REFRIGERATION
- Chapter 12 — HYDRONICS
- Chapter 13 — FUEL GAS PIPING
- Chapter 14 — PROCESS PIPING
- Chapter 15 — SOLAR ENERGY SYSTEMS
- Chapter 16 — STATIONARY POWER PLANTS
- Chapter 17 — REFERENCED STANDARDS
- Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
- Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
- Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
- Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
- Appendix E — SUSTAINABLE PRACTICES
- Appendix F — GEOTHERMAL ENERGY SYSTEMS
- Appendix G — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
- Appendix H — EXAMPLE CALCULATION OF OUTDOOR AIR RATE