CHBC · California Historical Building Code
Ducts, ventilating systems and grease hoods — new vs existing
If you are installing new ducts or changing a grease hood in a historic building, the CHBC requires you to meet the regular mechanical and fire‑protection code; existing ducts that aren’t safe may need fixes, but unaltered, nonhazardous old systems can sometimes remain with the enforcing agency’s approval.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
- New ducts must be built and installed to the same standards as current (regular) code — see § 8-902.7.
- Ventilating systems must be installed so they create no safety hazard; grease hoods and their exhaust must meet the regular code, and any existing grease‑hood system that is altered must be brought into compliance with the regular code — see § 8-902.8 and § 8-902.8.2.
- Existing ductwork that does not meet the regular code may remain in use only where the enforcing agency determines it does not constitute a safety or health hazard — see § 8-902.7.2.
The single most important rule: if you install something new (ducts, hoods or exhaust), or you alter an existing grease‑hood system, follow the regular code; existing unaltered systems may stay only if the enforcing agency agrees they are not hazardous.
Requirements in detail
Key terms (first use bolded)
- New ducts — ductwork installed as part of a new installation or complete replacement (must meet regular code). § 8-902.7.
- Existing duct systems — ductwork already in place in a historical building; may remain even if not fully code‑compliant unless the enforcing agency finds a safety/health hazard. § 8-902.7.2.
- Ventilating systems — general building ventilation equipment; must not create a safety hazard. § 8-902.8.1.
- Grease hoods / grease hood exhaust systems — commercial kitchen hoods and their ducts/fans (must comply with the regular code when furnished, installed, or altered). § 8-902.8.2.
- Regular code — the standard building/mechanical/fire codes adopted statewide (the CHBC defers to those for specifics). § 8-902.1 explains the relationship to the regular code.
Decision table — when to follow CHBC vs regular code
| Situation / Decision dimension | What CHBC requires (plain English) | Code Reference |
|---|---|---|
| Install brand‑new ducts | Must be constructed and installed per the regular code | § 8-902.7.1 |
| Existing ducts that don't meet regular code | May remain in use if the enforcing agency finds no safety/health hazard | § 8-902.7.2 |
| Install/alter a ventilating system | Must be installed so no safety hazard is created; follow regular code where applicable | § 8-902.8.1 |
| New grease hood / hood exhaust (installed) | Furnish and install in accordance with the regular code (no CHBC relaxation) | § 8-902.8.2 |
| Existing grease hood that is altered | Altered systems must comply with the regular code (bring up to regular code) | § 8-902.8.2 |
Notes: The CHBC establishes the decision boundaries (new vs existing vs altered). The mechanical, fire and building codes contain the technical requirements (materials, clearances, airflow, fire suppression, cleaning/inspection). For example, the California Mechanical Code contains the technical chapters on hood types, exhaust ducts and air movement (see California Mechanical Code §508 — §513 and §510 for exhaust ducts).
How the enforcing agency’s judgment appears in practice
- The CHBC explicitly allows the enforcing agency to let non‑conforming, existing systems remain where they do not create a safety or health hazard (§ 8-902.7.2). That is a case‑by‑case determination — expect requests for evaluation, testing, or documentation.
- For combustion/venting or where public safety is involved, the enforcing agency may require operational tests even for systems allowed to remain (see CHBC §§ 8-902.5.2 and 8-902.6.3 for similar authority).
Exceptions & special cases
- Existing ductwork that is noncompliant may stay in service only if the enforcing agency determines it poses no safety or health hazard; there is no blanket exemption. § 8-902.7.2.
- Any alteration to an existing grease hood or its exhaust triggers the requirement to meet the regular code (no “grandfathered” technical exceptions for altered systems). § 8-902.8.2.
- For ventilating systems generally, the CHBC standard is functional and safety‑based: the installation must not create a hazard; where technical details are needed, the regular code applies. § 8-902.8.1.
Common mistakes
- Assuming all existing ducts are automatically allowed to remain. The CHBC allows them to remain only if the enforcing agency finds no safety/health hazard — it’s not automatic (§ 8-902.7.2).
- Altering an old grease hood and expecting it to remain grandfathered. CHBC requires altered grease‑hood systems to comply with the regular code (§ 8-902.8.2).
- Installing a new duct or hood to historic appearance but omitting required fire protection, listed grease ducts, or makeup air — CHBC defers to the regular code for those technical safety elements (new installations must comply with the regular code — § 8-902.7.1 and § 8-902.8.2).
- Relying solely on CHBC text and not checking the referenced mechanical and fire code chapters (e.g., duct construction, hood type, exhaust termination, fire suppression and cleaning/inspection obligations are in the Mechanical and Fire Codes). The CHBC intentionally defers the technical detail to those codes.
Worked example — historic café renovating the kitchen
Scenario: A qualified historic café (in a building covered by the CHBC) will replace its stove and intends to modify the hood exhaust ductwork (change routing and add a new rooftop fan).
Step 1 — Determine whether work is a new installation or an alteration:
- Replacing the stove plus modifying the duct route = an alteration to the grease‑hood/exhaust system.
Step 2 — Apply CHBC requirements:
- Because the grease‑hood system is being altered, CHBC requires that the grease hood and its exhaust system be furnished and installed in accordance with the regular code. § 8-902.8.2.
Step 3 — Practical consequences:
- The owner will need to design the hood/exhaust per the California Mechanical Code (type of hood, airflow sizing, duct construction, clearances, rooftop termination, makeup air) and the Fire Code (fire‑suppression system, inspection/cleaning schedule). The CHBC does not relax those technical requirements for altered grease‑hood systems; it requires compliance with the regular code. § 8-902.8.2 and see mechanical code chapters on hoods/exhaust (for example, Type I/II hood requirements and exhaust duct rules).
Concrete numeric note (example constraint you will encounter from the regular code):
- If the work included a Type II hood for dishwashing, the Mechanical Code requires a net airflow of at least 200 cfm per linear foot of hood length for dishwashing appliances (a concrete technical requirement in the regular code). The CHBC would require adherence to that technical rule for an altered or new Type II installation. (See California Mechanical Code — Type II hood exhaust requirement).
Bottom line for the owner: Because you are altering the hood/exhaust, expect to bring the hood and ducts up to regular mechanical and fire‑protection standards and obtain plan review/approvals accordingly — CHBC § 8-902.8.2 makes the requirement explicit.
Related provisions (CHBC)
- § 8-902.1 — General: CHBC mechanical systems must comply with the regular code unless modified by the CHBC; describes scope and the enforcing agency’s alternative approval authority.
- § 8-902.5 — Combustion air: fuel‑burning appliances require sufficient combustion air; enforcing agency may require operational tests.
- § 8-902.6 — Venting of appliances: appliances required to be vented must be connected to approved venting systems; enforcement/testing authority described.
- § 8-903.1 — Plumbing general: mirrors the CHBC approach for plumbing — existing systems may remain if not hazardous; enforcing agency may approve alternatives. (Useful when ducts/hoods interface with plumbing or condensate disposal.)
Code references
Grounded in the retrieved California Historical Building Code — click a citation to read the verbatim passage:
CHBC § 8-902.5 High relevance — show source text
8-902.5 Combustion air.
8-902.5.1 All fuel-burning appliances and equipment shall be provided a sufficient supply of air for proper fuel combustion, ventilation and draft hood dilution.
8-902.5.2 The enforcing agency may require operational tests for combustion air systems which do not comply with applicable requirements of the regular code.
8-902.6 Venting of appliances.
8-902.6.1 Every appliance required to be vented shall be connected to an approved venting system. Venting systems shall develop a positive flow adequate to convey all combustion products to the outside atmosphere.
8-902.6.2 Masonry chimneys in structurally sound condition may remain in use for all fuel-burning appliances, provided the flue is evaluated and documentation provided that the masonry and grout are in good condition. Terra cotta chimneys and Type C metallic vents installed in concealed spaces shall not remain in use unless otherwise mitigated and approved on a case-by-case basis.
8-902.6.3 The enforcing agency may require operational tests for venting systems which do not comply with applicable requirements of the regular code.
8-902.7 Ducts.
8-902.7.1 New ducts shall be constructed and installed in accordance with applicable requirements of the regular code.
8-902.7.2 Existing duct systems which do not comply with applicable requirements of the regular code and do not, in the opinion of the enforcing agency, constitute a safety or health hazard may remain in use.
8-902.8 Ventilating systems.
2025 CALIFORNIA HISTORICAL BUILDING CODE 19
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MECHANICAL, PLUMBING AND ELECTRICAL REQUIREMENTS
8-902.8.1 Ventilating systems shall be installed so that no safety hazard is created.
8-902.8.2 Grease hoods and grease hood exhaust systems shall be furnished and installed in accordance with applicable requirements of the regular code. Existing systems which are altered shall comply with the regular code.
8-902.9 Miscellaneous equipment requirements.
8-902.9.1 The following appliances and equipment shall be installed so that no safety hazard is created: warm air furnaces, space heating equipment, vented decorative appliances, floor furnaces, vented wall furnaces, unit heaters, room heaters, absorption units, refrigeration equipment, duct furnaces, infrared radiant heaters, domestic incinerators, miscellaneous heat-producing appliances and water heaters.
8-902.9.2 Storage-type water heaters shall be equipped with a temperature- and pressure-relief valve in accordance with applicable requirements of the regular code.
SECTION 8-903 — PLUMBING
8-903.1 General. Plumbing systems shall comply with the regular code unless otherwise noted.
8-903.1.1 The provisions of the CHBC shall apply to the acceptance, location, installation, alteration, repair, relocation, replacement or addition of any plumbing system or equipment within or attached to a historical building.
8-903.1.2 Existing systems which do not, in the opinion of the enforcing agency, constitute a safety hazard may remain in use.
8-903.1.3 The enforcing agency may approve any alternative to these regulations which achieves reasonably equivalent life safety.
8-903.2 Residential occupancies.
CMC § 2025 High relevance — show source text
Systems that carry nonabrasive exhaust, such as smoke, moderate abrasives such as sawdust, and high abrasives such as manganese or acid vapors use product-conveying ducts. Part II provides the minimum fire safety requirements related to the design, installation, inspection, and maintenance of grease-type operations, such as cooking, for both fuel-gas and solid fuel. Cooking produces a significant amount of smoke, fumes, vapors, heat, and other pollutants. Therefore, acceptable kitchen ventilation is necessary to prevent fires from the build-up of grease and to provide the occupants protection from smoke, unpleasant odors, pollutants, and dangerous gases. There are two types of exhaust hoods (Type I and Type II) used in commercial kitchen applications.
xiv 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
FORMAT OF THE UNIFORM MECHANICAL CODE
Type I hoods are intended to be installed above equipment or appliances that generate grease or smoke. Type II hoods are intended to be installed above equipment or appliances that generate steam, vapor, heat, or odors and do not generate grease or smoke.
Chapter 6 Duct Systems. Chapter 6 regulates requirements for ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system. This chapter contains material and installation requirements for metal, gypsum, factory-made, flexible, and plastic ducts. It also contains provisions for duct insulation, dampers, fire protection, and automatic shutoff for the building’s air distribution system. It is worth noting that exhaust ducts are regulated by Chapter 5, and combustion air ducts are regulated by Chapter 7.
Chapter 7 Combustion Air. Chapter 7 regulates combustion air requirements for ventilation and dilution of flue gases for appliances installed in buildings. Fuel-gas appliances not regulated by chapter include direct vent appliances and Type I clothes dryers. Makeup air requirements for Type I clothes dryers are located in Chapter 5. Chapter 7 provides acceptable methods for supplying satisfactory combustion air to ensure proper combustion. Combustion air can be supplied by using indoor combustion air or by introducing the air from the outdoors.
Combustion is the rapid oxidation of fuel to release energy. The oxygen required to release the energy from the fuel normally comes from the air. Incomplete combustion of fuel occurs when inadequate oxygen is provided to the appliance. Combustion is needed to provide ventilation cooling for the casing and internal controls. When a lack of oxygen occurs, some of the carbon is not oxidized, and carbon monoxide forms.
Chapter 8 Chimneys and Vents. Chapter 8 regulates the installation, design, and construction of venting systems for fuel-burning appliances. The provisions addressed within this chapter follow procedures an installer would use to design or evaluate a venting system. Many requirements apply to the design and construction of venting systems, chimneys, installation of gas vents, and the sizing of venting system for a Category I appliance. Sizing venting systems require rigorous engineering calculations. However, the venting sizing requirements and sizing tables in this chapter already perform the calculations for the benefit of the end user.
Combustion appliances produce products of incomplete combustion, including potentially harmful carbon monoxide (CO). It is desirable to vent these products to the outdoors. Although the gas is clean-burning fuel, the products of combustion must not be allowed to collect within a building.
CHBC § 0.024 Medium relevance — show source text
024 inch (nominal 24
gauge) sheet metal over 1
inch glass fiber or min-
eral wool batts reinforced
with wire on rear face
with ventilated air space|18|12|9|6|6|4|5|3|3|3| |(4) 31⁄2 inch thick masonry
wall with ventilated air
space|––|12|––|6|––|6|––|6|––|6| |(5) 0.024 inch (nominal 24
gauge) sheet metal with
ventilated air space|18|12|9|6|6|4|5|3|3|2| |(6) 1⁄2 of an inch thick insula-
tion board with ventilated
air space|18|12|9|6|6|4|5|3|3|3| |(7) 0.024 inch (nominal 24
gauge) sheet metal with
ventilated air space over
0.024 inch (nominal 24
gauge) sheet metal with
ventilated air space|18|12|9|6|6|4|5|3|3|3| |(8) 1 inch glass fiber or
mineral wool batts sand-
wiched between two
sheets 0.024 inch (nom-
inal 24 gauge) sheet
metal with ventilated air
space|18|12|9|6|6|4|5|3|3|3|For SI units: 1 inch = 25.4 mm
Notes:
1 Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing. 2 All clearances shall be measured from the outer surface of the combustible material to the nearest point on the surface of the appliance, disregarding any intervening protection applied to the combustible material. 3 Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite the appliance or connector. 4 Where all clearance reduction systems use a ventilated air space, adequate provision for air circulation shall be provided as described. [See Figure 303.10.1(2) and Figure 303.10.1(3)] 5 At least 1 inch (25.4 mm) shall be between clearance reduction systems and combustible walls and ceilings for reduction systems using a ventilated air space. 6 Where a wall protector is installed on a single flat wall away from corners, it shall have a minimum 1 inch (25.4 mm) air gap. To provide adequate air circulation, the bottom and top edges, or only the side and top edges, or all edges shall be left open. 7 Mineral wool batts (blanket or board) shall have a minimum density of 8 pounds per cubic foot (lb/ft 3 ) (128 kg/m 3 ) and a minimum melting point of 1500°F (816°C). 8 Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1.0 British thermal unit inch per hour square foot degree Fahrenheit [Btu•in/(h•ft [2] - °F)] [0.1W/(m•K)] or less. 9 At least 1 inch (25.4 mm) shall be between the appliance and the protector. The clearance between the appliance and the combustible surface shall not be reduced below that allowed in Table 303.10.1. 10 All clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.
CHBC § 8-902.8.1 Medium relevance — show source text
MECHANICAL, PLUMBING AND ELECTRICAL REQUIREMENTS
8-902.8.1 Ventilating systems shall be installed so that no safety hazard is created.
8-902.8.2 Grease hoods and grease hood exhaust systems shall be furnished and installed in accordance with applicable requirements of the regular code. Existing systems which are altered shall comply with the regular code.
8-902.9 Miscellaneous equipment requirements.
8-902.9.1 The following appliances and equipment shall be installed so that no safety hazard is created: warm air furnaces, space heating equipment, vented decorative appliances, floor furnaces, vented wall furnaces, unit heaters, room heaters, absorption units, refrigeration equipment, duct furnaces, infrared radiant heaters, domestic incinerators, miscellaneous heat-producing appliances and water heaters.
8-902.9.2 Storage-type water heaters shall be equipped with a temperature- and pressure-relief valve in accordance with applicable requirements of the regular code.
SECTION 8-903 — PLUMBING
8-903.1 General. Plumbing systems shall comply with the regular code unless otherwise noted.
8-903.1.1 The provisions of the CHBC shall apply to the acceptance, location, installation, alteration, repair, relocation, replacement or addition of any plumbing system or equipment within or attached to a historical building.
8-903.1.2 Existing systems which do not, in the opinion of the enforcing agency, constitute a safety hazard may remain in use.
8-903.1.3 The enforcing agency may approve any alternative to these regulations which achieves reasonably equivalent life safety.
8-903.2 Residential occupancies.
8-903.2.1 Where toilet facilities are provided, alternative sewage disposal methods may be acceptable if approved by the local health department. In hotels, where private facilities are not provided, water closets at the ratio of one for each 15 rooms may be acceptable.
8-903.2.2 Toilet facilities are not required to be on the same floor or in the same building as sleeping rooms. Water-flush toilets may be located in a building immediately adjacent to the sleeping rooms. When alternative sewage disposal methods are utilized, they shall be located a minimum distance from the sleeping rooms or other locations as approved by the local health department.
8-903.2.3 Kitchen sinks shall be provided in all kitchens. The sink and countertop may be of any smooth nonabsorbent finish which can be maintained in a sanitary condition.
8-903.2.4 Hand washing facilities shall be provided for each dwelling unit and each hotel guest room. A basin and pitcher may be acceptable as adequate hand washing facilities.
8-903.2.5 Hot or cold running water is not required for each plumbing fixture, provided a sufficient amount of water is supplied to permit the fixture’s normal operation.
8-903.2.6 Bathtubs and lavatories with filler spouts less than 1 inch (25.4 mm) above the fixture rim may remain in use, provided there is an acceptable overflow below the rim.
8-903.2.7 Original or salvage water closets, urinals and flushometer valves shall be permitted in qualified historical buildings or properties. Historically accurate reproduction, nonlow-consumption water closets, urinals and flushometer valves shall be permitted except where historically accurate fixtures that comply with the regular code are available.
CHBC § 8-901.5 Medium relevance — show source text
8-901.5 Energy conservation. Qualified historical buildings or properties covered by this part are exempted from compliance with energy conservation standards. When new nonhistorical lighting and space conditioning system components, devices, appliances and equipment are installed, they shall comply with the requirements of Title 24, Part 6, The California Energy Code, except where the historical significance or character-defining features are threatened.
SECTION 8-902 — MECHANICAL
8-902.1 General. Mechanical systems shall comply with the regular code unless otherwise modified by this chapter.
8-902.1.1 The provisions of the CHBC shall apply to the acceptance, location, installation, alteration, repair, relocation, replacement or addition of any heating, ventilating, air conditioning, domestic incinerators, kilns or miscellaneous heat-producing appliances or equipment within or attached to a historical building.
8-902.1.2 Existing systems which do not, in the opinion of the enforcing agency, constitute a safety hazard may remain in use.
8-902.1.3 The enforcing agency may approve any alternative to the CHBC which would achieve equivalent life safety.
8-902.2 Heating facilities. All dwelling-type occupancies covered under this chapter shall be provided with heating facilities. Woodburning or pellet stoves or fireplaces may be acceptable as heating facilities.
8-902.3 Fuel oil piping and tanks. Fuel oil piping and tanks shall comply with regular code requirements except that the enforcing agency may waive such requirements where the lack of compliance does not create a safety or environmental hazard.
8-902.4 Heat-producing and cooling equipment. Heat-producing and cooling equipment shall comply with the regular code requirements governing equipment safety, except that the enforcing agency may accept alternatives which do not create a safety hazard.
8-902.5 Combustion air.
8-902.5.1 All fuel-burning appliances and equipment shall be provided a sufficient supply of air for proper fuel combustion, ventilation and draft hood dilution.
8-902.5.2 The enforcing agency may require operational tests for combustion air systems which do not comply with applicable requirements of the regular code.
8-902.6 Venting of appliances.
8-902.6.1 Every appliance required to be vented shall be connected to an approved venting system. Venting systems shall develop a positive flow adequate to convey all combustion products to the outside atmosphere.
8-902.6.2 Masonry chimneys in structurally sound condition may remain in use for all fuel-burning appliances, provided the flue is evaluated and documentation provided that the masonry and grout are in good condition. Terra cotta chimneys and Type C metallic vents installed in concealed spaces shall not remain in use unless otherwise mitigated and approved on a case-by-case basis.
8-902.6.3 The enforcing agency may require operational tests for venting systems which do not comply with applicable requirements of the regular code.
8-902.7 Ducts.
8-902.7.1 New ducts shall be constructed and installed in accordance with applicable requirements of the regular code.
8-902.7.2 Existing duct systems which do not comply with applicable requirements of the regular code and do not, in the opinion of the enforcing agency, constitute a safety or health hazard may remain in use.
8-902.8 Ventilating systems.
2025 CALIFORNIA HISTORICAL BUILDING CODE 19
CMC § 2025 Medium relevance — show source text
The building’s structural stability is protected by the regulations for cutting and notching of structural members.
Chapter 4 Ventilation Air. Chapter 4 regulates the minimum requirements for ventilation air supply, exhaust, and makeup air for occupiable spaces within a building. Building ventilation is one important factor affecting the relationship between airborne transmission of respiratory infections and the health and productivity of workers. Ventilation air may be composed of mechanical or natural ventilation, infiltration, recirculated air, transfer air, or a suitable combination of these. Providing a comfortable and healthy indoor environment for building occupants is of primary concern. When determining ventilation rates, typical and unusual significant sources of indoor pollution need to be controlled. Areas such as kitchens, bathrooms, and laundries are all built to allow specific functions. These spaces produce pollutants such as moisture, odors, volatile organic compounds, particles, or combustion byproducts. The purpose of local exhaust is to control concentrates of these pollutants in the room into which they were emitted and to reduce the spread of pollutants into other parts of the occupancy. Local exhaust ventilation is the source control for pollution that is expected in certain rooms. Using local exhaust to extract contaminants before they mix with the indoor environment is essential.
Chapter 5 Exhaust Systems. Chapter 5 regulates the minimum requirements for exhaust systems. Chapter 5 contains two parts: Part I provides exhaust requirements for environmental air ducts and product conveying systems; Part II provides exhaust requirements for commercial hoods and kitchen ventilation. Environmental air ducts include exhaust ducts used for transporting the air from domestic kitchens, bathrooms, shower rooms, locker rooms, janitor’s closets, and clothes dryers. Systems that carry nonabrasive exhaust, such as smoke, moderate abrasives such as sawdust, and high abrasives such as manganese or acid vapors use product-conveying ducts. Part II provides the minimum fire safety requirements related to the design, installation, inspection, and maintenance of grease-type operations, such as cooking, for both fuel-gas and solid fuel. Cooking produces a significant amount of smoke, fumes, vapors, heat, and other pollutants. Therefore, acceptable kitchen ventilation is necessary to prevent fires from the build-up of grease and to provide the occupants protection from smoke, unpleasant odors, pollutants, and dangerous gases. There are two types of exhaust hoods (Type I and Type II) used in commercial kitchen applications.
xiv 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
FORMAT OF THE UNIFORM MECHANICAL CODE
Type I hoods are intended to be installed above equipment or appliances that generate grease or smoke. Type II hoods are intended to be installed above equipment or appliances that generate steam, vapor, heat, or odors and do not generate grease or smoke.
Chapter 6 Duct Systems. Chapter 6 regulates requirements for ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system. This chapter contains material and installation requirements for metal, gypsum, factory-made, flexible, and plastic ducts. It also contains provisions for duct insulation, dampers, fire protection, and automatic shutoff for the building’s air distribution system. It is worth noting that exhaust ducts are regulated by Chapter 5, and combustion air ducts are regulated by Chapter 7.
CHBC § 1.24 Medium relevance — show source text
Figure 16 Stacking Terminal
Table 26 Specifications for Terminal Connectors − Aluminum Cable-to-Flat Bar (Figure 15 and Figure 16)
Cable Size
AWG or kcmilRefer to Approved for Purchase Col4 Col5 Col6 Col7 Col8 6-Ton Tool Dies # 7
12-Ton Tool Dies #
15-Ton Tool Dies #Cable Size
AWG or kcmilRefer to Approximate Dimensions (inches) Approximate Dimensions (inches) Approximate Dimensions (inches) Approximate Dimensions (inches) Approximate Dimensions (inches) Connector
CodeConnector
CodeCable Size
AWG or kcmilRefer to B C 1 L 1 T 1 OD OD OD 4 Figure 15 1.24 1.25 4.92 0.25 0.65 303829 W-BG
U-BG
U-BG82 2 1.10 0.91 5.62 0.25 0.65 303761 303761 1/0 1/0 1.10 0.91 5.62 0.25 0.65 303760 303760 2/0 2/0 1.60 1.25 5.43 0.25 0.91 303830 −
U26ART
U26ART84/0 4/0 1.60 1.25 5.75 0.30 0.91 303759 −
U28ART
U28ART8250 250 1.96 1.25 5.88 0.25 1.12 303831 −
U249ART
U249ART8350 350 1.91 1.62 6.84 0.38 1.12 303758 −
U31ART
U31ART8500/600 500/600 2.62 1.62 6.78 0.38 1.62 303832 −
U34ART
U34ART8700/7502 700/7502 2.65 1.62 8.22 0.62 1.62 303833 −
−
P39ART1,000/1,1002 1,000/1,1002 2.97 1.62 8.88 0.62 1.84 303834 −
−
P44ART1,2503 1,2503 2.58 2.60 7.53 0.51 1.84 303835 L7276 1,5003 1,5003 3.19 3.09 8.59 0.81 2.26 303836 L46ART6 1,7503 1,7503 3.69 3.33 8.38 0.86 2.46 303837 L735 or L735W6 2,0003 2,0003 3.69 3.57 8.50 0. CHBC § 11.5 Medium relevance — show source text
5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level|1.
Ordinary
temperature,
quick-response
sprinklers,
maximum 8 feet
3 inches
horizontal
spacing
2.
One line of
sprinklers at the
6-foot level and
the 11.5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Maximum
spacing|Maximum
spacing|100 ft2/head|100 ft2/head| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Area
(square feet)|Ordinary
temperature|Not
Applicable|Not
Applicable| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Area
(square feet)|High
temperature|2,000b|2,000b| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Density
(gpm/ft2)|Density
(gpm/ft2)|0.60|0.60| |**TABLE 5704.3.6.CHBC § 519.1 Medium relevance — show source text
519.1 Where Required. Type II hoods shall be installed above equipment and dishwashers that generate steam, heat, or products of combustion, and where grease or smoke is not present.
Exceptions:
(1) Dishwashing machines connected to a Type II duct system and exhausted directly to the outdoors.
(2) Dishwashing machines with a self-contained condensing system listed in accordance with UL 921 and installed in a space where the HVAC system has been engineered to accommodate the latent and sensible heat load emitted from such appliances as approved by the Authority Having Jurisdiction. Such equipment shall be provided with an interlocking device to prevent opening of the appliance prior to completion of its cycle. 519.2 Construction of Type II Hoods. Type II hoods constructed of steel shall be not less than 0.024 of an inch (0.61 mm) (No. 24 gauge). Hoods constructed of copper shall be of copper sheets weighing not less than 0.17 ounces per square inch (oz/in [2] ) (7.47 kg/m [2] ). Joints and seams shall be substantially tight. Solder shall not be used except for sealing a joint or seam. 519.3 Type II Hood Exhaust System Net Airflow. The net airflow for Type II hoods shall be in accordance with Section 508.5.1.5 for light-duty cooking appliances. The net airflow for Type II hoods serving dishwashing appliances shall comply with Section 519.3.1.
519.3.1 Dishwashing Appliances. The net airflow for Type II hoods used for dishwashing equipment shall be not less than 200 cubic feet per minute (0.094 m [3] /s) per linear foot (m) of hood length.
519.4 Type II Exhaust Duct Systems. Ducts and plenums serving Type II hoods shall be constructed of rigid metallic materials in accordance with Chapter 6. Duct bracing and supports shall comply with Chapter 6. Ducts subject to positive pressure shall be adequately sealed.
519.5 Termination of Type II Hood Exhaust System. The exhaust system shall terminate in accordance with Section 502.2.2. Rooftop terminations shall be directed away
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132 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
EXHAUST SYSTEMS
from roof surfaces within 40 inches (1016 mm). The discharge outlet of moisture conveying exhaust ducts, such as dishwasher exhaust ducts, shall not terminate over a public way or over an area where condensate or vapor could create a nuisance or hazard.
519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3.
519.7 Independent Exhaust Duct System. Single or combined Type II exhaust systems shall be independent of all other exhaust systems.
2025 CALIFORNIA MECHANICAL CODE 133
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
134 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE
CHAPTER 6 – DUCT SYSTEMS
CHBC § 403.3.1.1 Medium relevance — show source text
Spaces in which such systems are located shall be considered to be kitchens and shall be ventilated in accordance with Table 403.3.1.1 of the California Mechanical Code . For the purpose of determining the floor area required to be ventilated, each individual appliance shall be considered as occupying not less than 100 square feet (9.3 m [2] ). 3. Where cooking appliances are equipped with integral down-draft exhaust systems and such appliances and exhaust systems are listed and labeled for the application in accordance with NFPA 96, a hood shall not be required at or above them.
- A Type I hood shall not be required for an electric cooking appliance where an approved testing agency provides documentation that the appliance effluent contains 5 mg/m [3] or less of grease when tested at an exhaust flow rate of 500 cfm (0.236 m [3] /s) in accordance with UL 710B.
606.3 Operations and maintenance. Commercial cooking systems shall be operated, inspected and maintained in accordance with Sections 606.3.1 through 606.3.4.
606.3.1 Ventilation system. The ventilation system in connection with hoods shall be operated at the required rate of air movement, and grease filters listed and labeled in accordance with UL 1046 shall be in place where equipment under a kitchen grease hood is used.
606.3.2 Grease extractors. Where grease extractors are installed, they shall be operated when the commercial-type cooking equipment is used.
606.3.3 Cleaning. Hoods, grease-removal devices, fans, ducts and other appurtenances shall be cleaned at intervals as required by Sections 606.3.3.1 through 606.3.3.3.
606.3.3.1 Inspection. Hoods, grease-removal devices, fans, ducts and other appurtenances shall be inspected at intervals specified in Table 606.3.3.1 or as approved by the fire code official. Inspections shall be completed by qualified individuals.
TABLE 606.3.3.1—COMMERCIAL COOKING SYSTEM INSPECTION FREQUENCY Col2 TYPE OF COOKING OPERATIONS FREQUENCY OF INSPECTION High-volume cooking operations such as 24-hour cooking, charbroiling or wok cooking 3 months Low-volume cooking operations such as places of religious worship, seasonal businesses and senior centers 12 months Cooking operations utilizing solid fuel-burning cooking appliances 1 month All other cooking operations 6 months 606.3.3.2 Grease accumulation. If during the inspection it is found that hoods, grease-removal devices, fans, ducts or other appurtenances have an accumulation of grease, such components shall be cleaned in accordance with ANSI/IKECA C10.
606.3.3.3 Records. Records for inspections shall state the individual and company performing the inspection, a description of the inspection and when the inspection took place. Records for cleanings shall state the individual and company performing the cleaning and when the cleaning took place. Such records shall be completed after each inspection or cleaning and maintained.
2025 CALIFORNIA FIRE CODE 6-9
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
BUILDING SERVICES AND SYSTEMS
CHBC § 8-1 Medium relevance — show source text
CHAPTER 8 INTERIOR FINISHES. . . . . . . . . . . . . . . . . . . . . .8-1
801 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
802 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
803 Wall and Ceiling Finishes . . . . . . . . . . . . . . . . . . . . . . . . 8-3
804 Interior Floor Finish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6
805 Combustible Materials in Types I and II Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
806 Decorative Materials and Trim . . . . . . . . . . . . . . . . . . . 8-7
807 Insulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8
808 Acoustical Ceiling Systems . . . . . . . . . . . . . . . . . . . . . . 8-8
CHAPTER 9 FIRE PROTECTION AND LIFE
SAFETY SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1
901 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7
902 Fire Pump and Riser Room Size . . . . . . . . . . . . . . . . . . 9-7
903 Automatic Sprinkler Systems . . . . . . . . . . . . . . . . . . . . 9-8
904 Alternative Automatic Fire-Extinguishing Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17
905 Standpipe Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20
906 Portable Fire Extinguishers . . . . . . . . . . . . . . . . . . . . . 9-22
907 Fire Alarm and Detection Systems . . . . . . . . . . . . . . . 9-25
908 Emergency Alarm Systems . . . . . . . . . . . . . . . . . . . . . 9-43
909 Smoke Control Systems . . . . . . . . . . . . . . . . . . . . . . . . 9-43
910 Smoke and Heat Removal . . . . . . . . . . . . . . . . . . . . . . 9-51
CHBC § 507.6 Medium relevance — show source text
507.6 Notification of Change . . . . . . . . . 111
507.7 Pharmaceutical Compounding Exhaust Discharge . . . . . . . . . . . . 111
508.0 Type I Hoods . . . . . . . . . . . . . . . . 111
508.1 Where Required . . . . . . . . . . . . . . 111
508.2 Listed Type I Hood Assemblies . . 111
508.3 Construction of Type I Hoods . . . . 111
508.4 Supports . . . . . . . . . . . . . . . . . . . . 112
508.5 Hood Size . . . . . . . . . . . . . . . . . . . 112
Table 508.5.1.2 Extra-Heavy-Duty Cooking Appliance Airflow . . . . . . . . . . . . . 113
Table 508.5.1.3 Heavy-Duty Cooking Appliance
Airflow. . . . . . . . . . . . . . . . . . . . . . 113
Table 508.5.1.4 Medium-Duty Cooking Appliance
Airflow. . . . . . . . . . . . . . . . . . . . . . 113
Table 508.5.1.5 Light-Duty Cooking Appliance
Airflow. . . . . . . . . . . . . . . . . . . . . . 113
508.6 Solid-Fuel Hood Assemblies . . . . 114
508.7 Exhaust Outlets . . . . . . . . . . . . . . 114
509.0 Grease Removal Devices in
Hoods . . . . . . . . . . . . . . . . . . . . . . 114
509.1 Grease Removal Devices. . . . . . . 114
509.2 Installation . . . . . . . . . . . . . . . . . . 114
509.3 Solid-Fuel Grease Removal
Devices. . . . . . . . . . . . . . . . . . . . . 115
510.0 Exhaust Duct Systems . . . . . . . . . 115
510.1 General. . . . . . . . . . . . . . . . . . . . . 115
510.2 Clearance . . . . . . . . . . . . . . . . . . . 115
510.3 Openings . . . . . . . . . . . . . . . . . . . 115
510.4 Listed Grease Ducts . . . . . . . . . . . 116
510.5 Other Grease Ducts . . . . . . . . . . . 116
510.6 Exterior Installations . . . . . . . . . . . 117
xxxii
510.7 Interior Installations . . . . . . . . . . . 118
510.8 Underground Installations. . . . . . . 118
510.9 Termination of Type I Hood Exhaust System . . . . . . . . . . . . . . 119
510.10 Solid-Fuel Duct Systems . . . . . . . 120
511.0 Air Movement . . . . . . . . . . . . . . . . 120
511.1 Exhaust Fans for Commercial
Frequently asked questions
When can I leave old ducts in place without upgrading them?
If the ductwork is existing and the enforcing agency determines it does not create a safety or health hazard, it may remain in use per § 8-902.7.2. You should get the enforcing agency to document its determination because the allowance is discretionary.
If I repaint or reline an existing grease duct, is that an “alteration” that triggers the regular code?
Minor maintenance that does not change performance or routing may be considered repair; however, CHBC treats altered grease‑hood systems as requiring regular‑code compliance per § 8-902.8.2. If the work changes the system’s configuration, capacity, routing, or fire‑protection features, expect to meet the regular code and coordinate with the enforcing agency.
Does CHBC ever relax fire‑suppression or grease‑duct construction requirements for historic buildings?
No — for new installations and any altered grease‑hood systems the CHBC explicitly requires conformance with the regular code (which includes fire suppression and duct construction standards). § 8-902.8.2 is explicit on altered systems.
Who decides if an existing duct is a “safety or health hazard”?
The local enforcing agency (building official/authority having jurisdiction) makes that judgment under § 8-902.7.2; the CHBC gives them authority to require testing or corrective work where necessary.
Where do I find the technical requirements I must meet if my hood must comply with the regular code?
The technical details live in the California Mechanical Code (hood types, duct construction, airflow, makeup air) and the Fire Code (suppression, inspection and cleaning). See the Mechanical Code chapters on hoods/exhaust (for example, § 508–§ 513 and § 510 for exhaust ducts).
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