Chapter 5 — EXHAUST SYSTEMS
California Mechanical Code (Title 24, Part 4) · 2019 edition · updated 2026-09-10 · California
Italicized text is a California amendment to the model code, as printed in the official publication.
Sections in this part
- 501.1 Applicability.501.0 General. This chapter includes requirements for
- 502.2 Termination of Exhaust Ducts. Exhaust ducts shall
- 503.0 Motors, Fans, and Filters.503.1 General.
- 503.2 Fans.
- 504.0 Environmental Air Ducts.504.1 General. Where not specified in this chapter, exhaust
- 504.2 Independent Exhaust Systems.
- 504.3 Domestic Range. Ducts used for domestic kitchen
- 504.4 Clothes Dryers. A clothes dryer exhaust duct shall
- 505.2 Incompatible Materials. Incompatible materials
- 505.3 Flammability Limit.
- 504.5 Heat (Energy) Recovery Ventilators. Heat
- 504.6 Gypsum Wallboard Ducts. Bathroom and laundry
- 505.1 General.505.0 Product-Conveying Systems. A mechanical ventilation or exhaust system
- 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
- 505.8 Product-Conveying Ducts Classification.
- 505.7 Fire Detection and Alarm Systems. Unless the
- 505.9 Minimum Velocities and Circulation.
- 505.10 Makeup Air.
- 505.11 Hoods and Enclosures. Hoods and enclosures shall
- 506.2 Construction. Ducts used for conveying products
- 506.0 Product-Conveying Ducts.506.1 Materials. Materials used in product-conveying duct
- 506.3 Penetrations. Exhaust ducts shall not pass through
- 506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be
- 506.4 Condensate.
- 506.6 Explosion Venting. Ducts conveying explosive dusts
- 506.9 Protection from Physical Damage. Ducts
- 506.7 Supports.
- 506.8 Fire Protection. Sprinklers or other fire-protection
- 506.11 Clearance Reduction Methods.
- 506.10 Duct Clearances. Unless the conditions in Section
- 507.4 Clearance. Where enclosures are not required, hoods,
- 507.1 Type I Hood Exhaust System.507.0 General Requirements. Exhaust systems
- 507.2 Exhaust System. Cooking equipment used in
- 507.3 Listed Devices. Penetrations shall be sealed with
- 507.5 Drawings.
- 507.6 Notification of Change. Where required by the
- 508.1 Where Required.508.0 Type I Hoods. 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 1,
- 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
- 509.0 Grease Removal Devices in Hoods.509.1 Grease Removal Devices.
- 509.2 Installation. The distance between the grease
- 509.3 Solid-Fuel Grease Removal Devices. Where
- 510.0 Exhaust Duct Systems.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
- 510.4 Listed Grease Ducts. Listed grease ducts shall be
- 510.5 Other Grease Ducts.
- 510.6 Exterior Installations. The exterior portion of the
- 510.7 Interior Installations. In buildings more than one
- 510.8 Underground Installations. Grease ducts installed
- 511.0 Air Movement.
- 510.10 Solid-Fuel Duct Systems.
- 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.512.0 Auxiliary Equipment. Dampers shall not be installed in exhaust
- 512.2 Electrical Equipment. Wiring systems shall not be
- 512.3 Other Equipment.
- 512.4 Solid-Fuel Auxiliary Equipment. Where solid fuel
- 513.2 Types of Equipment. Fire-extinguishing equipment
- 513.6 System Annunciation.
- 513.3 Simultaneous Operation.
- 513.4 Fuel and Electric Power Shutoff. Upon activation
- 513.5 Manual Activation. A readily accessible means for
- 513.7 System Supervision. Where electrical power is
- 513.8 Special Design and Application.
- 513.9 Review and Certification. Where required, complete
- 513.10 Installation Requirements. Installation of systems
- 513.11 Portable Fire Extinguishers.
- 513.12 Maintenance. Portable fire extinguishers shall be
- 513.13 Solid-Fuel Fire-Extinguishing Equipment. Where
- 514.0 Procedures for the Use, Inspection, Testing, and
- 514.2 Inspection, Testing, and Maintenance.
- 514.3 Inspection for Grease Buildup. The entire exhaust
- 514.4 Cleaning of Exhaust Systems. Where, upon
- 514.5 Cooking Equipment Maintenance. Inspection and
- 515.1 Cooking Equipment.Equipment. Cooking equipment shall be
- 515.2 Operating Controls. Deep-fat fryers shall be equipped
- 516.1 General Requirements.516.0 Recirculating Systems.
- 516.2 Design Restrictions. Recirculating systems shall
- 516.6 Use and Maintenance. Automatic or manual covers
- 517.1 Venting Application.517.0 Solid-Fuel Cooking Operations.
- 516.3 Interlocks.
- 516.4 Location and Application Restrictions. The
- 516.5 Additional Fire Safety Requirements.
- 517.2 Location of Appliances. Appliances shall be
- 517.3 Hoods for Solid-Fuel Cooking. Hoods shall be
- 517.4 Exhaust Systems for Solid-Fuel Cooking. Where
- 517.6 Air Movement for Solid-Fuel Cooking. Exhaust
- 517.7 Fire-Extinguishing Equipment for Solid-FuelCooking.
- 517.8 Other Safety Requirements.
- 518.4 Airflow Switch or Transducer. An airflow switch or
- 518.5 Surface Materials. Surfaces located directly above
- 518.0 Downdraft Appliances.518.1 General. A downdraft appliance ventilation system
- 518.2 Ventilation System.
- 518.3 Fire-Extinguishing Equipment. Fire-extinguishing
- 519.0 Type II Hood Exhaust System Requirements.519.1 Where Required.
- 519.2 Construction of Type II Hoods.
- 519.3 Dishwashing Appliances. The net airflow for Type
- 519.4 Type II Exhaust Duct Systems. Ducts and plenums
- 519.5 Termination of Type II Hood Exhaust System.
- 519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3.
(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
>
| Adopting Agency | BSC | BSC- CG |
SFM | HCD | DSA | OSHPD | BSCC | DPH | AGR | DWR | CEC | CA | SL | SLC | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Adopting Agency |
**BSC ** | BSC- CG |
SFM | 1 |
2 |
1-AC | **AC ** | SS | SS/CC | 1 | 1R | 2 | 3 |
4 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 |
amended (amended sections listed below) |
X | X | X | X | **X ** | **X ** | X | **X ** | X | X | |||||||||||||
that are listed below |
|||||||||||||||||||||||
The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.
2019 CALIFORNIA MECHANICAL CODE 83
84 2019 CALIFORNIA MECHANICAL CODE
CHAPTER 5
EXHAUST SYSTEMS
502.0 Termination.502.1 Exhaust Opening Protection.¶
Exhaust openings terminating to the outdoors shall be covered with a corrosionresistant screen having not less than 1 ⁄4 of an inch (6.4 mm) openings, and shall have not more than 1 ⁄2 of an inch (12.7 mm) openings. Exception: Clothes dryers.
513.0 Fire-Extinguishing Equipment.513.1 General.¶
Fire-extinguishing equipment for the protection of grease removal devices, hood exhaust plenums, and exhaust duct systems shall be provided. [NFPA 96:10.1.1]
513.1.1 Protection. Cooking equipment that produces grease-laden vapors and is capable of being a source of ignition of grease in the hood, grease removal device, or duct shall be protected by fire-extinguishing equipment.
[NFPA 96:10.1.2]
108 2019 CALIFORNIA MECHANICAL CODE
EXHAUST SYSTEM
515.0 Minimum Safety Requirements for Cooking¶
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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.501.0 General. This chapter includes requi…
- 502.2 Termination of Exhaust Ducts. Exhaust ducts shall
- 503.0 Motors, Fans, and Filters.503.1 General. Motors and fans…
- 503.2 Fans. Parts of fans in contact with explosive or flammab…
- 504.0 Environmental Air Ducts.504.1 General. Where not specifi…
- 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
- 505.2 Incompatible Materials. Incompatible materials
- 505.3 Flammability Limit. Unless the circumstances stipulated …
- 504.5 Heat (Energy) Recovery Ventilators. Heat
- 504.6 Gypsum Wallboard Ducts. Bathroom and laundry
- 505.1 General.505.0 Product-Conveying Systems. A mechanical ve…
- 505.4 Air-Moving Devices. Air-moving devices shall be
- 505.5 Generating Flames, Sparks, or Hot Materials. Operations …
- 505.6 Fire Dampers. Fire dampers shall be permitted to be
- 505.8 Product-Conveying Ducts Classification. Product-conveyin…
- 505.7 Fire Detection and Alarm Systems. Unless the
- 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
- 506.2 Construction. Ducts used for conveying products
- 506.0 Product-Conveying Ducts.506.1 Materials. Materials used …
- 506.3 Penetrations. Exhaust ducts shall not pass through
- 506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be
- 506.4 Condensate. Joints in duct construction shall be liquidt…
- 506.6 Explosion Venting. Ducts conveying explosive dusts
- 506.9 Protection from Physical Damage. Ducts
- 506.7 Supports. Supports shall be of noncombustible materials,…
- 506.8 Fire Protection. Sprinklers or other fire-protection
- 506.11 Clearance Reduction Methods. It shall be permitted to p…
- 506.10 Duct Clearances. Unless the conditions in Section
- 507.4 Clearance. Where enclosures are not required, hoods,
- 507.1 Type I Hood Exhaust System.507.0 General Requirements. E…
- 507.2 Exhaust System. Cooking equipment used in
- 507.3 Listed Devices. Penetrations shall be sealed with
- 507.5 Drawings. A drawing(s) of the exhaust system installatio…
- 507.6 Notification of Change. Where required by the
- 508.1 Where Required.508.0 Type I Hoods. Type I hoods shall be…
- 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 1,
- 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
- 509.0 Grease Removal Devices in Hoods.509.1 Grease Removal Dev…
- 509.2 Installation. The distance between the grease
- 509.3 Solid-Fuel Grease Removal Devices. Where
- 510.0 Exhaust Duct Systems.510.1 General. Ducts shall not pass…
- 510.2 Clearance. Clearance between ducts and combustible
- 510.3 Openings. Openings shall be provided at the sides
- 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 buildings more than one
- 510.8 Underground Installations. Grease ducts installed
- 511.0 Air Movement.
- 510.10 Solid-Fuel Duct Systems. Where solid-fuel cooking equip…
- 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.512.0 Auxiliary Equipment. Dampers shall not be …
- 512.2 Electrical Equipment. Wiring systems shall not be
- 512.3 Other Equipment. Fume incinerators, thermal recovery uni…
- 512.4 Solid-Fuel Auxiliary Equipment. Where solid fuel
- 513.2 Types of Equipment. Fire-extinguishing equipment
- 513.6 System Annunciation. Upon activation of an automatic fir…
- 513.3 Simultaneous Operation. Fixed pipe extinguishing systems…
- 513.4 Fuel and Electric Power Shutoff. Upon activation
- 513.5 Manual Activation. A readily accessible means for
- 513.7 System Supervision. Where electrical power is
- 513.8 Special Design and Application. Hoods containing automat…
- 513.9 Review and Certification. Where required, complete
- 513.10 Installation Requirements. Installation of systems
- 513.11 Portable Fire Extinguishers. Portable fire extinguisher…
- 513.12 Maintenance. Portable fire extinguishers shall be
- 513.13 Solid-Fuel Fire-Extinguishing Equipment. Where
- 514.0 Procedures for the Use, Inspection, Testing, and
- 514.2 Inspection, Testing, and Maintenance. Maintenance of the…
- 514.3 Inspection for Grease Buildup. The entire exhaust
- 514.4 Cleaning of Exhaust Systems. Where, upon
- 514.5 Cooking Equipment Maintenance. Inspection and
- 515.1 Cooking Equipment.Equipment. Cooking equipment shall be
- 515.2 Operating Controls. Deep-fat fryers shall be equipped
- 516.1 General Requirements.516.0 Recirculating Systems. Recirc…
- 516.2 Design Restrictions. Recirculating systems shall
- 516.6 Use and Maintenance. Automatic or manual covers
- 517.1 Venting Application.517.0 Solid-Fuel Cooking Operations.…
- 516.3 Interlocks. The recirculating system shall be provided w…
- 516.4 Location and Application Restrictions. The
- 516.5 Additional Fire Safety Requirements. In addition to the …
- 517.2 Location of Appliances. Appliances shall be
- 517.3 Hoods for Solid-Fuel Cooking. Hoods shall be
- 517.4 Exhaust Systems for Solid-Fuel Cooking. Where
- 517.6 Air Movement for Solid-Fuel Cooking. Exhaust
- 517.7 Fire-Extinguishing Equipment for Solid-FuelCooking. Soli…
- 517.8 Other Safety Requirements. Metal-fabricated solidfuel co…
- 518.4 Airflow Switch or Transducer. An airflow switch or
- 518.5 Surface Materials. Surfaces located directly above
- 518.0 Downdraft Appliances.518.1 General. A downdraft applianc…
- 518.2 Ventilation System. The downdraft appliance ventilation …
- 518.3 Fire-Extinguishing Equipment. Fire-extinguishing
- 519.0 Type II Hood Exhaust System Requirements.519.1 Where Req…
- 519.2 Construction of Type II Hoods. Type II hoods constructed…
- 519.3 Dishwashing Appliances. The net airflow for Type
- 519.4 Type II Exhaust Duct Systems. Ducts and plenums
- 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 — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
- Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE