CRC · California Residential Code
Regulator vent piping, vent terminus and venting limitations
Regulator vent lines must use approved materials, end in a protected outdoor fitting, be at least 3 feet from ignition sources, be protected from flooding and blockage (screens/antiflood fittings), and not be manifolded with diaphragm-bleed lines; PVC Schedule 40/80 is allowed for remote outdoor runs but not indoors.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
Regulator vent piping and vent terminations must be sized, routed, and terminated so vent discharge cannot be blocked or create a hazard. Key requirements (materials, termination details, clearance, antiflood protection, and prohibition of certain common manifolds) are found in § 1308.4 and associated paragraphs; the code also references materials requirements through § 1308.4.10.5. Where regulators are installed in chases or indoors, venting location and limits are governed by the venting/chase rules such as § 1310.5.1.
The vent outlet must be designed and located so that it cannot be blocked, cannot expose occupants to ignitable mixtures, and cannot be submerged — and the vent piping material and routing must follow the 1308.4 series requirements.
Requirements in detail
Definitions & terms (first mentions bolded)
- Vent terminus — the outside end or fitting at the end of a regulator vent line; it must be designed to prevent entry of water, insects, and other foreign matter. § 1308.4
- Vent limiting means — a listed device incorporated in some regulators that limits vent flow such that the regulator may be treated differently for vent routing (see exceptions). § 1308.4
- Regulator vent piping (plastic) — permitted for remote terminations only as PVC Schedule 40 or 80; PVC vent piping shall not be installed indoors. § 1308.4.4.1
Core obligations (short bullets)
- Vent materials and construction must comply with the material requirements in the 1308.4 series (the code groups materials rules through § 1308.4.10.5). § 1308.4 / § 1308.4.10.5
- The vent terminus must be protected against entry of water/insects/foreign matter that could cause blockage. § 1308.4
- Vents shall terminate not less than 3 feet (914 mm) from a possible source of ignition. § 1308.4
- Where vent termination can be submerged by flood or snow, install an antiflood-type breather vent fitting or locate the terminus above expected flood/snow level. § 1308.4
- Install vent piping to minimize static loads and bending moments on regulators and gas pressure control devices. § 1308.4
- Vent piping from pressure regulators and gas pressure controls shall not be connected to a common manifold that serves a bleed line from a diaphragm-type gas valve. § 1308.4
Chase / indoor venting limitations
- If regulators are placed in a vertical chase (see Chapter 1310 rules), venting follows these alternate paths:
- For gases lighter than air: regulators with a vent limiting means may be vented into the chase; regulators without a vent limiting means must be vented directly to outdoors or to a point within the top 1 foot (305 mm) of the chase. § 1310.5.1
- For gases heavier than air: regulator vents must be vented directly to the outdoors (no venting into chase allowed). § 1310.5.1
Materials rules (decision-critical)
- Plastic vent piping used to connect regulator vents to remote vent terminations shall be PVC (Schedule 40 and 80). PVC vent piping shall not be installed indoors. § 1308.4.4.1
Decision-relevant table
| Decision factor | Required value / limit | Code reference |
|---|---|---|
| Minimum horizontal clearance from a possible source of ignition | 3 ft (914 mm) | § 1308.4 |
| Vent terminus protection (water/insects/blockage) | Vent terminus must be designed to prevent entry | § 1308.4 |
| Antiflood protection where terminus may be submerged | Install antiflood-type breather vent fitting or raise terminus above expected flood/snow height | § 1308.4 |
| Allowed plastic for regulator vent runs | PVC, Schedule 40 or 80 only; not indoors | § 1308.4.4.1 |
| Connecting vents to a common manifold that also serves diaphragm valve bleed lines | Prohibited | § 1308.4 |
| Venting into a vertical chase (lighter-than-air gas) | Allowed only if regulator has vent limiting means; otherwise vent to outdoors or to top 1 ft of chase | § 1310.5.1 |
Exceptions & special cases
- Exception for listed devices: A regulator and vent limiting means combination listed to CSA/ANSI Z21.80/CSA 6.22 is not required to be vented to the outdoors. Also, a listed gas appliance regulator factory-equipped with a vent limiting device is not required to be vented outdoors. These exceptions are in the code text alongside the 1308.4 rules. § 1308.4 (exceptions)
- Remote vent piping may use PVC Schedule 40/80, but remember PVC vent piping is prohibited indoors; installations must follow appliance/manufacturer instructions and local adoption rules. § 1308.4.4.1
- When a regulator is inside a chase or meter room, the regulator must still be vented to outdoors except where the chase provisions expressly permit different handling (see § 1310.5.1). § 1310.5.1
Note about availability of controlling paragraphs: the code references materials rules through § 1308.4.10.5 but the full text of § 1308.4.10.5 (and the general text of § 1308.1) was not present in the provided files. Where the file text points to those sections, I have cited the surrounding, available language; if you need the literal text of § 1308.4.10.5 or § 1308.1, provide the full CRC/CMC file pages or I can pull those sections next.
Common mistakes
- Installing PVC regulator vent piping indoors (PVC is allowed only for remote outdoor terminations). § 1308.4.4.1
- Terminating vents closer than 3 ft to ignition sources or building openings. § 1308.4
- Failing to protect the vent terminus against insects/water (screens/caps) causing blockage. § 1308.4
- Connecting regulator vent piping into a common manifold that also serves a diaphragm-type gas valve bleed line (this is prohibited). § 1308.4
- Venting heavier-than-air gas into a chase (must go outdoors). § 1310.5.1
Worked example — concrete scenario
Scenario: A service regulator is installed on an exterior wall at ground level. The regulator vent will terminate at an exterior PVC fitting 2 ft horizontally from a rooftop gas heater ignition source and 10 in (254 mm) below an overhanging soffit that channels rain.
Code application:
- Minimum horizontal clearance: the regulator vent must be at least 3 ft (914 mm) from any possible source of ignition. A 2 ft separation fails the clearance requirement. Relocate the terminus or the ignition source, or reroute the vent. § 1308.4
- Overhang / rain: the vent terminus must be designed to prevent entry of water; an overhang that channels rain requires either a protected fitting or a revised termination to avoid flooding/ingress. § 1308.4
- Material: using PVC Schedule 40 for the remote exterior run is permitted, but PVC vent piping shall not be installed indoors — confirm the run never passes through occupied interior spaces. § 1308.4.4.1
Actions to comply: move the vent terminus to be at least 3 ft (914 mm) from the heater ignition, add a screened/protected cap or antiflood device if standing water or snow is possible, and ensure the PVC run never goes indoors. § 1308.4 § 1308.4.4.1
(Utility note: some gas utilities prescribe additional clearances — for example, PG&E’s internal guidance recommends 36 in (3 ft) from openings and larger clearances from forced-air intakes. Those utility rules are not a substitute for the CRC text but are often enforced by the utility. See PG&E guidance for their requirements. )
Related provisions
- § 1308.4 — Regulator vent piping general requirements (materials, termination, clearance, antiflood, manifolds).
- § 1308.4.4.1 — Regulator vent piping — PVC Schedule 40/80 allowed for remote terminations; PVC not permitted indoors.
- § 1310.5.1 — Piping in vertical chases — rules that control when regulators may be vented into chases (lighter vs heavier than air, vent limiting means, top 1 ft rule).
- § 1308.6.4 and § 1308.7 — referenced by the chase/pressure-reduction language for downstream overpressure and venting (see chase rules).
- Utility guidance (non-code) — PG&E regulator vent location recommendations (clearances and screening) may impose tighter field requirements; check utility approval for meter/meter-room installations.
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 1308.4 High relevance — show source text
(2) Materials for vent piping shall be in accordance with Section 1308.4 through Section 1308.4.10.5. (3) The vent terminus shall be designed to prevent the entry of water, insects, and other foreign matter that could cause blockage. (4) Vent piping shall be installed to minimize static loads and bending moments placed on the regulators and gas pressure control devices.
(5) Vents shall terminate not less than 3 feet (914 mm) from a possible source of ignition. (6) At locations where a vent termination could be submerged during floods or snow accumulations, an antiflood-type breather vent fitting shall be installed, or the vent terminal shall be located above the height of the expected floodwaters or snow.
(7) Vent piping from pressure regulators and gas pressure controls shall not be connected to a common manifold that serves a bleed line from a diaphragm-type gas valve.
[NFPA 54:5.14]
1309.0 Excess Flow Valve.
1309.1 General. Where automatic excess flow valves are installed, they shall be listed in accordance with ANSI Z21.93/CSA 6.30 and shall be sized and installed in accordance with the manufacturers’ instructions. [NFPA 54:5.12]
1310.0 Gas Piping Installation. 1310.1 Piping Underground. Underground gas piping shall be installed with sufficient clearance from any other underground structure to avoid contact therewith, to allow maintenance, and to protect against damage from proximity to other structures. Underground plastic piping shall be installed with sufficient clearance or shall be insulated from any source of heat so as to prevent the heat from impairing the serviceability of the pipe. [NFPA 54:7.1.1.1, 7.1.1.2] 1310.1.1 Cover Requirements. Underground piping systems shall be installed with a minimum of 12 inches (305 mm) of cover. The minimum cover shall be increased to 18 inches (457 mm) if external damage to the pipe or tubing from external forces is likely to result. Where a minimum of 12 inches (305 mm) of cover cannot be provided, the piping shall be installed in conduit. [NFPA 54:7.1.2.1 – 7.1.2.1(B)]
1310.1.2 Trenches. The trench shall be graded so that the pipe has a firm, substantially continuous bearing on the bottom of the trench. [NFPA 54:7.1.2.2]
1310.1.2.1 Backfilling. Where flooding of the trench is done to consolidate the backfill, care shall be exer
cised to see that the pipe is not floated from its firm bearing on the trench bottom. [NFPA 54:7.1.2.3]
1310.1.3 Protection Against Corrosion. Steel pipe and steel tubing installed underground shall be installed in accordance with Section 1310.1.3.1 through Section 1310.1.3.9. [NFPA 54:7.1.3]
CRC § 5.9.2 High relevance — show source text
(1) Check valves.
(2) Three-way valves (of the type that completely closes one side before starting to open the other side).
(3) Reverse flow indicators controlling positive shutoff valves.
(4) Normally closed air-actuated positive shutoff pressure regulators. [NFPA 54:5.9.2] 1308.11 Low-Pressure Protection. A protective device shall be installed between the meter and the appliance or equipment if the operation of the appliance or equipment is such that it could produce a vacuum or a dangerous reduction in gas pressure at the meter. Such protective devices include, but are not limited to, mechanical, diaphragm-operated, or electrically operated low-pressure shutoff valves. [NFPA 54:5.10]
1308.12 Shutoff Valves. Shutoff valves shall be selected in
accordance with Table 1308.12. Shutoff valves of size 1 inch
(25 mm) National Pipe Thread and smaller shall be listed and labeled. Where used outdoors, such use shall be in accordance with the manufacturer’s recommendation. [NFPA 54:5.11]
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282 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
FUEL GAS PIPING
Exceptions: (1) A regulator and vent limiting means combination listed as complying with CSA/ANSI Z21.80/CSA 6.22, shall not be required to be vented to the outdoors.
(2) A listed gas appliance regulator factory equipped with a vent limiting device is not required to be vented to the outdoors.
(2) Materials for vent piping shall be in accordance with Section 1308.4 through Section 1308.4.10.5. (3) The vent terminus shall be designed to prevent the entry of water, insects, and other foreign matter that could cause blockage. (4) Vent piping shall be installed to minimize static loads and bending moments placed on the regulators and gas pressure control devices.
(5) Vents shall terminate not less than 3 feet (914 mm) from a possible source of ignition. (6) At locations where a vent termination could be submerged during floods or snow accumulations, an antiflood-type breather vent fitting shall be installed, or the vent terminal shall be located above the height of the expected floodwaters or snow.
(7) Vent piping from pressure regulators and gas pressure controls shall not be connected to a common manifold that serves a bleed line from a diaphragm-type gas valve.
[NFPA 54:5.14]
1309.0 Excess Flow Valve.
1309.1 General. Where automatic excess flow valves are installed, they shall be listed in accordance with ANSI Z21.93/CSA 6.30 and shall be sized and installed in accordance with the manufacturers’ instructions. [NFPA 54:5.12]
1310.0 Gas Piping Installation. 1310.1 Piping Underground. Underground gas piping shall be installed with sufficient clearance from any other underground structure to avoid contact therewith, to allow maintenance, and to protect against damage from proximity to other structures. Underground plastic piping shall be installed with sufficient clearance or shall be insulated from any source of heat so as to prevent the heat from impairing the serviceability of the pipe.
CRC § 1310.5.1 High relevance — show source text
1310.5.1 Pressure Reduction. Where pressure reduction is required in branch connections for compliance with Section 1310.6, such reduction shall take place either inside the chase or immediately adjacent to the outside wall of the chase. Regulator venting and downstream overpressure protection shall comply with Section 1308.6.4 and Section 1308.7. The regulator shall be accessible for service and repair, and vented in accordance with one of the following:
(1) Where the fuel gas is lighter than air, regulators equipped with a vent limiting means shall be permitted to be vented into the chase. Regulators not equipped with a vent limiting means shall be permitted to be vented either directly to the outdoors or to a point within the top 1 foot (305 mm) of the chase.
(2) Where the fuel gas is heavier than air, the regulator vent shall be vented only directly to the outdoors.
[NFPA 54:7.4.1]
1310.5.2 Chase Construction. Chase construction
shall comply with local building codes with respect to fire resistance and protection of horizontal and vertical openings. [NFPA 54:7.4.2]
1310.5.3 Ventilation. A chase shall be ventilated to the
outdoors and only at the top. The opening(s) shall have a minimum free area [in square inches (square meters)] equal to the product of one-half of the maximum pressure in the piping [in pounds per square inch (kilopas
cals)] times the largest nominal diameter of that piping
[in inches (millimeters)], or the cross-sectional area of the chase, whichever is smaller. Where more than one fuel gas piping system is present, the free area for each system shall be calculated and the largest area used.
[NFPA 54:7.4.3]
1310.6 Maximum Operating Pressure in Buildings. The maximum operating pressure for any piping systems located inside buildings shall not exceed 5 psi (34 kPa) unless one or more of the following conditions are met:
(1) The piping joints are welded or brazed.
(2) The piping is joined by fittings listed to CSA/ANSI LC 4/CSA 6.32 and installed according to the manufacturer’s installation instructions.
(3) The piping joints are flanged and all pipe-to-flange connections are made by welding or brazing.
(4) The piping is located in a ventilated chase or otherwise enclosed for protection against accidental gas accumulation.
(5) The piping is located inside buildings or separate areas of buildings used exclusively for one of the following:
(a) Industrial processing or heating
(b) Research
(c) Warehousing
(d) Boiler or mechanical rooms
(6) The piping is a temporary installation for buildings under construction.
(7) The piping serves appliances or equipment used for agricultural purposes.
(8) The piping system is an LP-Gas piping system with an operating pressure greater than 20 psi (138 kPa) and complies with NFPA 58. [NFPA 54:5.4.4]
1310.6.1 LP-Gas Systems Operating Below -5°F (-21°C). LP-Gas systems designed to operate below 5°F (-21°C) or with butane or a propane-butane mix shall be designed to either accommodate liquid LP-Gas or to prevent LP-Gas vapor from condensing back into a liquid. [NFPA 54:5.4.5]
CRC § 7.3.4 High relevance — show source text
the tubing and the finished wall and extends at least 4 inches (102 mm) beyond concealed penetrations of plates, firestops, wall studs, and so on.
(2) The tubing is installed in single runs and is not rigidly secured. [NFPA 54:7.3.4]
1310.4.4 Industrial Occupancies. In industrial occupancies, gas piping in solid floors such as concrete shall be laid in channels in the floor and covered to permit access to the piping with a minimum of damage to the building. Where piping in floor channels could be exposed to excessive moisture or corrosive substances, the piping shall be protected in an approved manner.
[NFPA 54:7.3.5.1]
1310.4.5 Other Occupancies. In other than industrial occupancies and where approved by the Authority Having Jurisdiction, gas piping embedded in concrete floor slabs constructed with Portland cement shall be surrounded with a minimum of 1 [1] ⁄ 2 inches (38 mm) of concrete and shall not be in physical contact with other metallic structures such as reinforcing rods or electrically neutral conductors. All piping, fittings, and risers shall be protected against corrosion in accordance with Section 1310.3.1. Piping shall not be embedded in concrete slabs containing quickset additives or cinder aggregate. [NFPA 54:7.3.5.2]
1310.5 Piping in Vertical Chases. Where gas piping exceeding 5 psi (34 kPa) is located within vertical chases in accordance with Section 1310.6, the requirements of Section 1310.5.1 through Section 1310.5.3 shall apply. [NFPA 54:7.4]
1310.5.1 Pressure Reduction. Where pressure reduction is required in branch connections for compliance with Section 1310.6, such reduction shall take place either inside the chase or immediately adjacent to the outside wall of the chase. Regulator venting and downstream overpressure protection shall comply with Section 1308.6.4 and Section 1308.7. The regulator shall be accessible for service and repair, and vented in accordance with one of the following:
(1) Where the fuel gas is lighter than air, regulators equipped with a vent limiting means shall be permitted to be vented into the chase. Regulators not equipped with a vent limiting means shall be permitted to be vented either directly to the outdoors or to a point within the top 1 foot (305 mm) of the chase.
(2) Where the fuel gas is heavier than air, the regulator vent shall be vented only directly to the outdoors.
[NFPA 54:7.4.1]
1310.5.2 Chase Construction. Chase construction
shall comply with local building codes with respect to fire resistance and protection of horizontal and vertical openings. [NFPA 54:7.4.2]
1310.5.3 Ventilation. A chase shall be ventilated to the
outdoors and only at the top. The opening(s) shall have a minimum free area [in square inches (square meters)] equal to the product of one-half of the maximum pressure in the piping [in pounds per square inch (kilopas
cals)] times the largest nominal diameter of that piping
CRC § 1208.5 High relevance — show source text
FUEL GAS PIPING
(2) A listed gas appliance regulator factory equipped with a vent limiting device is not required to be vented to the outdoors.
(2) Materials for vent piping shall be in accordance with Section 1208.5 through Section 1208.5.12.5.
(3) The vent terminus shall be designed to prevent the entry of water, insects, and other foreign matter that could cause blockage.
(4) Vent piping shall be installed to minimize static loads and bending moments placed on the regulators and gas pressure control devices.
(5) Vents shall terminate not less than 3 feet (914 mm) from a possible source of ignition.
(6) At locations where a vent termination could be submerged during floods or snow accumulations, an antiflood-type breather vent fitting shall be installed, or the vent terminal shall be located above the height of the expected flood waters or snow.
(7) Vent piping from pressure regulators and gas pressure controls shall not be connected to a common manifold
that serves a bleed line from a diaphragm-type gas valve.
[NFPA 54:5.14]
TABLE 1208.13
MANUAL GAS VALVE STANDARDS
[NFPA 54: TABLE 5.11]
1209.0 Excess Flow Valve.
1209.1 General. Where automatic excess flow valves are installed, they shall be listed in accordance with ANSI Z21.93/CSA 6.30 and shall be sized and installed in accor dance with the manufacturers’ instructions. [NFPA 54:5.12]
1210.0 Gas Piping Installation.
1210.1 Piping Underground. Underground gas piping shall be installed with sufficient clearance from any other underground structure to avoid contact therewith, to allow maintenance, and to protect against damage from proximity to other structures. Underground plastic piping shall be installed with sufficient clearance or shall be insulated from any source of heat so as to prevent the heat from impairing the serviceability of the pipe. [NFPA 54:7.1.1.1 – 7.1.1.2]
1210.1.1 Cover Requirements. Underground piping systems shall be installed with a minimum of 12 inches (305 mm) of cover. The minimum cover shall be increased to 18 inches (457 mm) if external damage to the pipe or tubing from external forces is likely to result. Where a minimum of 12 inches (305 mm) of cover cannot be provided, the piping shall be installed in conduit.
[NFPA 54:7.1.2.1 – 7.1.2.1(B)]
1210.1.2 Trenches. The trench shall be graded so that the pipe has a firm, substantially continuous bearing on the bottom of the trench. [NFPA 54:7.1.2.2]
1210.1.2.1 Backfilling. Where flooding of the trench is done to consolidate the backfill, care shall be exercised to see that the pipe is not floated from its firm bearing on the trench bottom. [NFPA 54:7.1.2.3]
1210.1.3 Protection Against Corrosion. Steel pipe and steel tubing installed underground shall be installed in accordance with Section 1210.1.3.1 through Section 1210.1.3.9. [NFPA 54:7.1.3]
CRC § 10-09 High relevance — show source text
B. PG&E will position gas regulators to minimize the length of the regulator vent lines and to ensure adequate venting capacity.
- “ −C. PG&E will specify regulator vent lines, in accordance with Gas Design Standard H 93, Regulator Vent Lines
- Regulator Vent Locations
A. Service regulator vents must terminate in a safe outside location that complies with the following criteria:
(1) The regulator vent must not terminate near any sources of ignition or openings into the building. The regulator vent must be 36 inches horizontally from sources of ignition and openings into the building, and this clearance area will extend 10 feet above and 36 inches below the regulator vent termination.
(2) A minimum lateral distance of 8 feet from a forced air intake. This includes the intake vents for the gas meter room.
(3) Within any location that is under display platforms or show windows in commercial buildings, including any permanent, elevated, display floors or platforms associated with the window.
(4) Within any location that is under building overhangs, where the overhang is likely to direct venting gas into a building opening.
B. Vents for all natural gas regulator and gas monitor diaphragm equipment must terminate above a reasonable flood level. Regulator vent extensions must be separate lines, terminated so they are protected from the rain and provided with screened fittings to prevent insects and other debris from entering the vent.
C. Vent locations must have final approval by PG&E.
Page 6 of 11 PG&E Internal Information, SL2 © 2013 Pacific Gas & Electric Company. All Rights Reserved. Prepared by: AAJ7
Gas Meter Room J-16
Rev. #03a 10-09-13
Requirements for PG&E-Owned Equipment
- Natural Gas Metering
Electrical grounding or bonding to PG&E’s metering facility piping or equipment or to customer-owned house lines inside of the meter room is not permitted.
- Land-Line Cable and Conduit
Customers with an estimated average use of 10,000 therms per month or more are required to install, own, and maintain a nominal 1” diameter conduit and a telephone cable. PG&E’s requirements for the conduit are described below.
A. Applicant/customer must extend the conduit and telephone cable from the closest telephone service location (i.e., outdoor “general purpose” area) to a location specified by PG&E that will be at or near the gas metering facilities. The maximum allowable distance from the telephone service location to PG&E’s gas meter is 50 feet.
B. Conduit must terminate within 3 feet of the gas meter location.
C. Applicant must install a conduit seal, inside the gas meter room, within 18 inches of the boundary where the conduit enters the gas meter room. There must be no conduit fitting between the boundary and the seal. PG&E will pour the conduit seal.
D. Applicant/customer is responsible for all charges and costs associated with installing the telephone facilities necessary to provide telephone service for PG&E’s gas metering facilities which are to be used for PG&E’s purposes.
E. PG&E is responsible for establishing telephone service and for the ongoing telephone service charges for gas metering purposes.
- Additional Equipment Needed to Support Gas Meters
Consideration must be given to the design requirements for:
A. Volume pulse output connections.
B. Electronic correctors.
CRC § 10-09 High relevance — show source text
Mechanical fans and all other electric devices must be explosion proof and meet the requirements of the NFPA-70: National Electric Code for Class I, Division 1, Group D locations.
Mechanical fans and detection equipment must be continuously monitored in case of failure. Alarms for trouble and failure must be installed in accordance with NFPA-72, National Fire Alarm Code.
Prepared by: AAJ7 PG&E Internal Information, SL2 © 2013 Pacific Gas & Electric Company. All Rights Reserved. Page 5 of 11
Gas Meter Room J-16
Rev. #03a 10-09-13
Natural Gas Regulator Requirements
- Natural Gas Regulators
Typically PG&E will install natural gas service regulators and overpressure protection devices outside of a meter room. Applicants/customers who want to install gas service regulators and overpressure protection devices inside of a meter room must provide PG&E with the written justification as part of the application. The preferred gas riser, meter and regulator location is outside and adjacent to the building being served. On an exception basis, gas meters and regulators may be installed in a specially designed gas meter room. PG&E must approve all gas meter and regulator installations and the gas meter room design in advance of any construction. If acceptable to PG&E, the following additional conditions apply:
A. Each gas service regulator installed within a building must be located as near as practical to the point of the service line entrance into the meter room, and as specified by PG&E.
B. PG&E will specify materials and designs for any overpressure protection devices needed, as outlined in Items 2 and 3 below.
- Regulator Vent Lines
A. Regulators and any additional overpressure protection equipment installed indoors must be vented to the outdoors. The customer is required to provide holes (penetrations) through walls or ceilings for these vents. In rare situations where the meter room location is not adjacent to an outside wall, the customer is required to install the vent piping from the meter room to the outside wall (PG&E will determine pipe size and location). PG&E will be responsible for connecting the vent piping to the regulator or overpressure protection device.
B. PG&E will position gas regulators to minimize the length of the regulator vent lines and to ensure adequate venting capacity.
- “ −C. PG&E will specify regulator vent lines, in accordance with Gas Design Standard H 93, Regulator Vent Lines
- Regulator Vent Locations
A. Service regulator vents must terminate in a safe outside location that complies with the following criteria:
(1) The regulator vent must not terminate near any sources of ignition or openings into the building. The regulator vent must be 36 inches horizontally from sources of ignition and openings into the building, and this clearance area will extend 10 feet above and 36 inches below the regulator vent termination.
(2) A minimum lateral distance of 8 feet from a forced air intake. This includes the intake vents for the gas meter room.
(3) Within any location that is under display platforms or show windows in commercial buildings, including any permanent, elevated, display floors or platforms associated with the window.
(4) Within any location that is under building overhangs, where the overhang is likely to direct venting gas into a building opening.
CRC § 1208.14.1 High relevance — show source text
1208.14.1 Special Local Conditions. Where local conditions include earthquake, tornado, unstable ground, or flood hazards, special consideration shall be given to increased strength and flexibility of piping supports and connections. [NFPA 54:5.13.2]
1208.15 Pressure Regulator and Pressure Control Venting. The venting of the atmospheric side of diaphragms in line pressure regulators, gas appliance regulators, and gas pressure limit controls shall be in accordance with all of the following:
(1) An independent vent pipe to the outdoors, sized in accordance with the device manufacturer’s instructions, shall be provided where the location of a device is such that a discharge of fuel gas will cause a hazard. For devices other than appliance regulators, vents are not required to be independent where the vents are connected to a common manifold designed in accordance with engineering methods to minimize backpressure in the event of diaphragm failure and such design is approved.
Exceptions:
(1) A regulator and vent limiting means combination listed as complying with CSA/ANSI Z21.80/CSA 6.22, shall not be required to be vented to the outdoors.
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FUEL GAS PIPING
(2) A listed gas appliance regulator factory equipped with a vent limiting device is not required to be vented to the outdoors.
(2) Materials for vent piping shall be in accordance with Section 1208.5 through Section 1208.5.12.5.
(3) The vent terminus shall be designed to prevent the entry of water, insects, and other foreign matter that could cause blockage.
(4) Vent piping shall be installed to minimize static loads and bending moments placed on the regulators and gas pressure control devices.
(5) Vents shall terminate not less than 3 feet (914 mm) from a possible source of ignition.
(6) At locations where a vent termination could be submerged during floods or snow accumulations, an antiflood-type breather vent fitting shall be installed, or the vent terminal shall be located above the height of the expected flood waters or snow.
(7) Vent piping from pressure regulators and gas pressure controls shall not be connected to a common manifold
that serves a bleed line from a diaphragm-type gas valve.
[NFPA 54:5.14]
TABLE 1208.13
MANUAL GAS VALVE STANDARDS
[NFPA 54: TABLE 5.11]
1209.0 Excess Flow Valve.
1209.1 General. Where automatic excess flow valves are installed, they shall be listed in accordance with ANSI Z21.93/CSA 6.30 and shall be sized and installed in accor dance with the manufacturers’ instructions. [NFPA 54:5.12]
1210.0 Gas Piping Installation.
CRC § 0.0508 High relevance — show source text
(1) A steel striker barrier not less than 0.0508 of an inch (1.3 mm) thick, or equivalent, is installed between the tubing and the finished wall and extends at least 4 inches (102 mm) beyond concealed penetrations of plates, firestops, wall studs, and so on.
(2) The tubing is installed in single runs and is not rigidly secured. [NFPA 54:7.3.4] 1210.4.4 Industrial Occupancies. In industrial occupancies, gas piping in solid floors such as concrete shall be laid in channels in the floor and covered to permit access to the piping with a minimum of damage to the building. Where piping in floor channels could be exposed to excessive moisture or corrosive substances, the piping shall be protected in an approved manner.
[NFPA 54:7.3.5.1] 1210.4.5 Other Occupancies. In other than industrial occupancies and where approved by the Authority Having Jurisdiction, gas piping embedded in concrete floor slabs constructed with portland cement shall be surrounded with a minimum of 1 [1] ⁄ 2 inches (38 mm) of concrete and shall not be in physical contact with other metallic structures such as reinforcing rods or electrically neutral conductors. All piping, fittings, and risers shall be protected against corrosion in accordance with Section 1210.3.1. Piping shall not be embedded in concrete slabs containing quickset additives or cinder aggregate. [NFPA 54:7.3.5.2] 1210.5 Piping in Vertical Chases. Where gas piping exceeding 5 psi (34 kPa) is located within vertical chases in accordance with Section 1208.4(4), the requirements of Section 1210.5.1 through Section 1210.5.3 shall apply. [NFPA 54:7.4] 1210.5.1 Pressure Reduction. Where pressure reduction is required in branch connections for compliance with Section 1208.4, such reduction shall take place either inside the chase or immediately adjacent to the outside wall of the chase. Regulator venting and downstream overpressure protection shall comply with Section 1208.7.4 and Section 1208.8 through Section 1208.10.4. The regulator shall be
accessible for service and repair and vented in accordance with one of the following:
(1) Where the fuel gas is lighter than air, regulators equipped with a vent limiting means shall be permitted to be vented into the chase. Regulators not equipped with a vent limiting means shall be permitted to be vented either directly to the outdoors or to a point within the top 1 foot (305 mm) of the chase.
(2) Where the fuel gas is heavier than air, the regulator vent shall be vented only directly to the outdoors.
[NFPA 54:7.4.1]
1210.5.2 Chase Construction. Chase construction shall comply with local building codes with respect to fire resistance and protection of horizontal and vertical openings. [NFPA 54:7.4.2]
CRC § 5.9.1.1 High relevance — show source text
Gas and air combustion mixers incorporating double diaphragm “zero” or “atmosphere” governors or regulators shall require no further protection unless connected directly to compressed air or oxygen at pressures of 5 psi (34 kPa) or more. [NFPA 54:5.9.1.1 – 5.9.1.2]
1208.11.1 Protective Devices. Protective devices
shall include but not be limited to the following:
(1) Check valves.
(2) Three-way valves (of the type that completely closes one side before starting to open the other side).
(3) Reverse flow indicators controlling positive shutoff valves.
(4) Normally closed air-actuated positive shutoff pressure regulators. [NFPA 54:5.9.2]
1208.12 Low-Pressure Protection. A protective device shall be installed between the meter and the appliance or equipment if the operation of the appliance or equipment is such that it could produce a vacuum or a dangerous reduction in gas pressure at the meter. Such protective devices include, but are not limited to, mechanical, diaphragm-operated, or electrically operated low-pressure shutoff valves. [NFPA 54:5.10]
1208.13 Shutoff Valves. Shutoff valves shall be selected in
accordance with Table 1208.13. Shutoff valves of size 1 inch
(25 mm) National Pipe Thread and smaller shall be listed and labeled. Where used outdoors, such use shall be in accordance with the manufacturer’s recommendation. [NFPA 54:5.11]
1208.14 Expansion and Flexibility. Piping systems shall be designed to prevent failure from thermal expansion or contraction. [NFPA 54:5.13.1]
1208.14.1 Special Local Conditions. Where local conditions include earthquake, tornado, unstable ground, or flood hazards, special consideration shall be given to increased strength and flexibility of piping supports and connections. [NFPA 54:5.13.2]
1208.15 Pressure Regulator and Pressure Control Venting. The venting of the atmospheric side of diaphragms in line pressure regulators, gas appliance regulators, and gas pressure limit controls shall be in accordance with all of the following:
(1) An independent vent pipe to the outdoors, sized in accordance with the device manufacturer’s instructions, shall be provided where the location of a device is such that a discharge of fuel gas will cause a hazard. For devices other than appliance regulators, vents are not required to be independent where the vents are connected to a common manifold designed in accordance with engineering methods to minimize backpressure in the event of diaphragm failure and such design is approved.
Exceptions:
(1) A regulator and vent limiting means combination listed as complying with CSA/ANSI Z21.80/CSA 6.22, shall not be required to be vented to the outdoors.
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222 2025 CALIFORNIA PLUMBING CODE
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FUEL GAS PIPING
(2) A listed gas appliance regulator factory equipped with a vent limiting device is not required to be vented to the outdoors.
(2) Materials for vent piping shall be in accordance with Section 1208.5 through Section 1208.5.12.5.
CRC § 7.3.5.2 High relevance — show source text
Piping shall not be embedded in concrete slabs containing quickset additives or cinder aggregate. [NFPA 54:7.3.5.2] 1210.5 Piping in Vertical Chases. Where gas piping exceeding 5 psi (34 kPa) is located within vertical chases in accordance with Section 1208.4(4), the requirements of Section 1210.5.1 through Section 1210.5.3 shall apply. [NFPA 54:7.4] 1210.5.1 Pressure Reduction. Where pressure reduction is required in branch connections for compliance with Section 1208.4, such reduction shall take place either inside the chase or immediately adjacent to the outside wall of the chase. Regulator venting and downstream overpressure protection shall comply with Section 1208.7.4 and Section 1208.8 through Section 1208.10.4. The regulator shall be
accessible for service and repair and vented in accordance with one of the following:
(1) Where the fuel gas is lighter than air, regulators equipped with a vent limiting means shall be permitted to be vented into the chase. Regulators not equipped with a vent limiting means shall be permitted to be vented either directly to the outdoors or to a point within the top 1 foot (305 mm) of the chase.
(2) Where the fuel gas is heavier than air, the regulator vent shall be vented only directly to the outdoors.
[NFPA 54:7.4.1]
1210.5.2 Chase Construction. Chase construction shall comply with local building codes with respect to fire resistance and protection of horizontal and vertical openings. [NFPA 54:7.4.2]
1210.5.3 Ventilation. A chase shall be ventilated to the outdoors and only at the top. The opening(s) shall have a minimum free area [in square inches (square meters)] equal to the product of one-half of the maximum pressure in the piping [in pounds per square inch (kilopascals)] times the largest nominal diameter of that piping [in inches (millimeters)], or the cross-sectional area of the chase, whichever is smaller. Where more than one fuel gas piping system is present, the free area for each system shall be calculated and the largest area used. [NFPA 54:7.4.3] 1210.6 Gas Pipe Turns. Changes in direction of gas pipe shall be made by the use of fittings, factory bends, or field bends. [NFPA 54:7.5] 1210.6.1 Metallic Pipe. Metallic pipe bends shall comply with the following:
(1) Bends shall be made only with bending tools and procedures intended for that purpose.
(2) All bends shall be smooth and free from buckling, cracks, or other evidence of mechanical damage.
(3) The longitudinal weld of the pipe shall be near the neutral axis of the bend.
(4) Pipe shall not be bent through an arc of more than 90 degrees.
(5) The inside radius of a bend shall be not less than 6 times the outside diameter of the pipe. [NFPA 54:7.5.1] 1210.6.2 Plastic Pipe. Plastic pipe bends shall comply with the following:
(1) The pipe shall not be damaged, and the internal diameter of the pipe shall not be effectively reduced.
(2) Joints shall not be located in pipe bends.
CRC § 927.2 Medium relevance — show source text
REFRIGERATORS
Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.2
Factory-built . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.1
Ventilating kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.3
REGULATOR VENT PIPING . . . . . . . . . . . . . . . . 1308.4.4.1
REGULATORS
Combustion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1009.0
Gas appliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . 923.5
Gas-pressure regulators . . . . . . . . . . . . . . . . . . . 1007.0
Vent piping . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.4.4.1
RETURN DUCT SIZING . . . . . . . . . . . . . . . . . . . . . . . 601.2.1
RISER HEAT PIPE
Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220.0
ROOFTOP TERMINATIONS
Chimneys. . . . . . . . . . . . . . . . . . . . . . . 802.5.4, 802.7.2,
803.1.10, 803.2.20
Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511.1.3.1
Gas vents . . . . . . . . . . . . . . . . . . . . . . 802.6.1, 802.7.2,
803.1.10, 803.2.20
ROOM HEATERS . . . . . . . . . . . . . . . . . . . . . . . 220.0, 915.0
ROOM
Boiler . . . . . . . . . . . . . . . . . 204.0, 303.2, 1001.2, 1001.4
Equipment . . . . . . . . . . . . . . . . . . . . . . . . 303.2, 305.1.3
HPM storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0
Machinery . . . . . . . . . . . . 1106.0, 1107.0, 1108.0, 1115.3
Used for ventilation . . . . . . . . . . . . . . . . . . . . . 402.2.1.6
CRC § 1104.1 Medium relevance — show source text
Permissible . . . . . . . . . . . . . . . . . . . . . . . . Table 1104.1
Pressure-limiting devices . . . . . . . . . . . . . . . . . . . 1111.0
Pressure-relief devices . . . . . . . . . . . . . . 1112.0, 1112.9,
1112.10, 1112.11
1113.4, 1113.5, 1115.4
Probability . . . . . . . . . . . . . . . 1103.2, 1103.2.1, 1103.2.2
Protection from
mechanical damage . . . . . . . . . . . . . . . . . . . 1109.4.1
Requirements for . . . . . . . . . . . . . . . . . . . . . . . . . 1104.0
Self-contained mechanical
refrigeration systems . . . . . . . . . . . . . . . . . . . . . 933.3
Self-contained refrigerators
and freezers . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.1
Unit coolers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.2
Ventilation of room . . . . . . . . . . . . . . . . . . 1105.5, 1107.0
REFRIGERATORS
Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.2
Factory-built . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933.1
Ventilating kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 927.3
REGULATOR VENT PIPING . . . . . . . . . . . . . . . . 1308.4.4.1
REGULATORS
Combustion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1009.0
Gas appliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . 923.5
Gas-pressure regulators . . . . . . . . . . . . . . . . . . . 1007.0
Vent piping . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.4.4.1
RETURN DUCT SIZING . . . . . . . . . . . . . . . . . . . . . . . 601.2.1
RISER HEAT PIPE
Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220.0
ROOFTOP TERMINATIONS
CRC § 901.1 Medium relevance — show source text
901.1 Applicability. This chapter shall govern the materials, design, and installation of plumbing vent systems. 901.2 Vents Required. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage and backpressure, and air circulation shall be ensured throughout all parts of the drainage system by means of vent pipes installed in accordance with the requirements of this chapter and as otherwise required by this code. 901.3 Trap Seal Protection. The vent system shall be designed to prevent a trap seal from being exposed to a pressure differential that exceeds 1 inch water column (0.24 kPa) on the outlet side of the trap.
902.0 Vents Not Required.
902.1 Interceptor. Vent piping shall be permitted to be omitted on an interceptor where such interceptor acts as a primary settling tank and discharges through a horizontal indirect waste pipe into a secondary interceptor. The second interceptor shall be properly trapped and vented. 902.2 Bars, Soda Fountains, and Counter. Traps serving sinks that are part of the equipment of bars, soda fountains, and counters need not be vented where the location and construction of such bars, soda fountains, and counters are such as to make it impossible to do so. Where such conditions exist, said sinks shall discharge using approved indirect waste pipes into a floor sink or other approved type of recep tor.
903.0 Materials.
903.1 Applicable Standards. Vent pipe and fittings shall comply with the applicable standards referenced in Table 701.2, except that:
(1) No galvanized steel or 304 stainless steel pipe shall be installed underground and shall be not less than 6 inches (152 mm) aboveground.
(2) ABS and PVC DWV piping installations shall be in accordance with the firestop protection requirements in the California Building Code . Except for individual single-family dwelling units, materials exposed within ducts or plenums shall have a flame-spread index of not more than 25 and a smoke-developed index of not more than 50 where tested in accordance with ASTM E84 or UL 723. Plastic piping installed in plenums shall be tested in accordance with all requirements of ASTM E84 or UL 723. Mounting methods, supports and sample sizes of materials for testing that are not specified in ASTM E84 or UL 723 shall be prohibited.
903.1.1 [HCD 1 & HCD 2] ABS or PVC installations are limited to not more than two stories of areas of resi- dential accommodation.
903.1.2 [HCD 1] All malleable iron vents shall be gal- vanized.
903.1.3 [OSHPD 1, 2, 3, 4 & 5] ABS and PVC instal- lations are not allowed.
903.2 Use of Copper or Copper Alloy Tubing. Copper or copper alloy tube for underground drainage and vent piping shall have a weight of not less than that of copper or copper alloy drainage tube type DWV. 903.2.1 Aboveground. Copper or copper alloy tube for aboveground drainage and vent piping shall have a weight of not less than that of copper or copper alloy drainage tube type DWV. 903.2.2 Prohibited Use. Copper or copper alloy tube shall not be used for chemical or industrial wastes as
defined in Section 811.0.
CRC § 403.7 Medium relevance — show source text
1
Table 403.7_Notes 11 & 12_
||||X|X||||||||||||||||||||This state agency does not adopt sections identified with the following symbol: 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.
2025 CALIFORNIA MECHANICAL CODE 67
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68 2025 CALIFORNIA MECHANICAL CODE
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CHAPTER 4
VENTILATION AIR
401.0 General.
401.1 Applicability. This chapter contains requirements for ventilation air supply, exhaust, and makeup air requirements for occupiable spaces within a building. [OSHPD 1, 1R, 2, 3, 4 & 5] See Sections 406.0 through 419.0. [SFM] Air filters shall comply with all requirements of Part 12, Title 24, Chap- ter 12-71, SFM Standard 12-71-1. Spaces within buildings, except those within a dwelling unit in residential occupancies where occupants are nontransient, shall comply with Section 402.0 through Section 404.0. Requirements for ventilation air rate for dwelling units in residential occupancies, where the occupants are nontransient, shall be in accordance with Section 405.0 or ASHRAE 62.2.
401.2 Indoor Swimming Pools. The design of ventilation systems serving an indoor aquatic facility (natatorium) shall comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC).
401.3 Filters. [BSC-CG & DSA-SS] In mechanically ven- tilated buildings, provide regularly occupied areas of the building with air filtration media for outside and return air that provides at least a Minimum Efficiency Reporting Value (MERV) of 13. MERV 13 filters shall be installed prior to occupancy, and recommendations for maintenance with fil- ters of the same value shall be included in the operation and maintenance manual in compliance with Chapter 5, Division 5.5 of the California Green Building Standards Code (CAL- Green).
Exception: Existing mechanical equipment.
401.3.1 Labeling. Installed filters shall be clearly labeled by the manufacturer indicating the MERV rating.
402.0 Ventilation Air.
402.1 Occupiable Spaces. Occupiable spaces listed in Table 402.1 shall be designed to have ventilation (outdoor) air for occupants in accordance with this chapter. [DSA-SS] Ven- tilation air requirements for occupancies regulated by the California Energy Commission are found in the California Energy Code.
[CEC] Ventilation air requirements for occupancies regu- lated by the California Energy Commission and found in the California Energy Code supersede those of the California Mechanical Code.
CRC § 1220.4.2 Medium relevance — show source text
8|1220.4.2 – 1220.4.6| |1221.7|1221.6| |1308.2 – 1308.4.1|1308.3 – 1308.5.1| |Table 1308.3.1|Table 1308.4.1| |1308.4.2|1308.5.2| |1308.4.2.2 – 1308.6.4|1308.5.2.1 – 1308.7.3| |Table 1308.4.6.2|Table 1308.5.6.2| |1308.6.5 – 1308.13.1|1308.7.7 – 1308.14.1| |1312.1.2 – 1312.1.3|1312.1.1 – 1312.1.2| |Chapter 17|Appendix F| |Chapter 18|Chapter 17| |D 103.2|D 103.1| |E 503.5.6.7|E 503.5.6.6| |E 503.5.7.2 – E 503.5.7.6|E 503.5.7.1 – E 503.5.7.5| |Table E 503.5.7.2|Table E 503.5.7.1| |Table E 503.5.7.6|Table E 503.5.7.5| |Table E 503.5.10.1.2(1)|Table E 503.5.10(1)| |Table E 503.5.10.1.2(2)|Table E 503.5.10(2)| |E 503.5.10.1.2|E 503.5.10| |E 503.5.10.2 – E 503.5.10.2.2|E 503.5.10.1 – E 503.5.10.1.2| |E 503.5.12.1|E 503.5.12| |E 503.5.12.2|E 503.5.12.1| |E 503.6.5.4|E 503.6.5.4.1|
xxii 2025 CALIFORNIA MECHANICAL CODE
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Uniform Mechanical Code – 2024 Edition:
The Uniform Mechanical Code contains complete requirements for the installation and maintenance of heating, ventilating, cooking and refrigeration systems.
Uniform Mechanical Code Illustrated Training Manual:
CRC § 5303.16.1 Medium relevance — show source text
1, 5303.16.1, 5303.16.2, 5306.1, 5306.2, 5306.2.1, 5306.2.2, 5307.4.6, 5503.1.2, 5503.5.2, 5504.2.1.2, 5504.2.2.2, 5505.4.1, 5604.2, Table 5604.5.2(3), 5605.5, 5701.3, 5704.2.7.7, 5704.2.8.1, 5704.2.8.2, 5704.2.9.3, 5704.2.9.4, 5704.3.3.5, 5704.3.7.1, 5704.3.8, 5705.3.4, 5705.3.5.3, 5705.3.7.1, 5705.3.7.2, 5705.3.7.3, 5705.3.7.4, 5705.3.7.5.1, 5706.2.3, 5706.4.1, 5803.1.1, 5806.4.3, 5808.1, 5808.3, 5808.3.2, 5906.2.2, 5906.2.3, 5906.4.2, 6003.1.4.2, 6005.3.1, 6109.11.2, 6204.1.2, 6306.4, 6404.1.4, 6604.1
CEBC—25: California Existing Building Code
102.3, 1011.5.2, 1103.1, 1104.18, 1105.5.2
CMC—25: California Mechanical Code
201.3, 308.3, 605.1, 605.2.1.1, 605.2.1.2, 605.2.1.3, 605.2.1.4, 605.2.1.5, 605.3, 605.4, 605.4.2.3, 605.4.2.5, 605.5.2, 605.7, 606.1, 606.2, 608.1, 608.3, 608.4, 608.5, 608.8, 608.9.1, 608.10, 608.17, 610.1.1, 903.2.11.4, 904.14, 907.3.1, 909.1, 909.10.2, 909.13.1, 910.4.7, 915.6.1, 1006.2.2.3, 1011.16, 1020.6.1, 1207.4.7, 1207.6.1, 1207.6.1.2.2, 1207.11.8, 2104.2.1, 2105.3, 2301.1, 2301.6, 2309.3.1.2, 2311.3.1, 2311.4.3, 2311.8.2, 2311.
CRC § 101.5 Medium relevance — show source text
101.5 Validity. Where a provision of this code, or the application thereof to a person or circumstance, is held invalid, the remainder of the code, or the application of such provision to other persons or circumstances, shall not be affected thereby.
102.0 Applicability. 102.1 Conflicts Between Codes. Where the requirements within the jurisdiction of this mechanical code conflict with the requirements of the plumbing code, the plumbing code shall prevail. In instances where this code, applicable standards, or the manufacturer’s installation instructions conflict, the more stringent provisions shall prevail. Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall prevail. [OSHPD 1, 1R, 2, 3, 4 & 5] See Chapter 1, Division I, Section 1.1.7
102.2 Existing Installations. Mechanical systems lawfully in existence at the time of the adoption of this code shall be permitted to have their use, maintenance, or repair continued where the use, maintenance, or repair is in accordance with the original design and location and no hazard to life, health, or property has been created by such mechanical system.
102.3 Maintenance. Mechanical systems, materials, and appurtenances, both existing and new, of a premise under the Authority Having Jurisdiction shall be maintained in operating condition. Devices or safeguards required by this code shall be maintained in accordance with the code edition under
which installed.
The owner or the owner’s designated agent shall be responsible for maintenance of mechanical systems. To determine compliance with this subsection, the Authority Having Jurisdiction shall be permitted to cause a mechanical system to be reinspected.
102.3.1 Commercial HVAC Systems. Commercial HVAC systems both existing and new, and parts thereof shall be inspected and maintained in operating condition in accordance with ASHRAE/ACCA 180. The owner or the owner’s designated agent shall be responsible for maintenance of mechanical systems and equipment. To determine compliance with this subsection, the Authority Having Jurisdiction shall be permitted to cause a HVAC system to be reinspected. 102.3.2 Residential HVAC Systems. Residential HVAC systems both existing and new, and parts thereof shall be inspected in accordance with ACCA 4 QM. The owner or the owner’s designated agent shall be responsible for maintenance of mechanical systems and equipment. To determine compliance with this subsection, the Authority Having Jurisdiction shall be permitted to cause a HVAC system to be reinspected.
102.4 Additions, Alterations, Renovations, or Repairs. Additions, alterations, renovations, or repairs shall conform to that required for a new system without requiring the existing mechanical system to be in accordance with the requirements of this code. Additions, alterations, renovations, or repairs shall not cause an existing system to become unsafe, insanitary or overloaded.
Additions, alterations, renovations, or repairs to existing mechanical system installations shall comply with the provisions for new construction, unless such deviations are found to be necessary and are first approved by the Authority Having Jurisdiction. 102.5 Health and Safety. Where compliance with the provisions of this code fails to eliminate or alleviate a nuisance, or other dangerous or insanitary condition that involves health or safety hazards, the owner or the owner’s agent shall install such additional mechanical system facilities or shall make such repairs or alterations as ordered by the Authority Having Jurisdiction. **102.6 Changes in Building Occupancy.
CRC § 2025 Medium relevance — show source text
Chapter 9 Roof Assemblies.
Chapter 9 regulates the design and construction of roof assemblies. A roof assembly includes the roof deck, vapor retarder, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings.
The types of roof covering materials and installation regulated by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and photovoltaic shingles. Chapter 9 also provides requirements for roof drainage, flashing, above deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
Chapter 10 Chimneys and Fireplaces.
Chapter 10 contains requirements for the safe construction of masonry chimneys and fireplaces and establishes the standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; the factory-built type relies on the listing and labeling method of approval. Chapter 10 provides the requirements for seismic reinforcing and anchorage of masonry fireplaces and chimneys.
Chapter 11 [RE] Energy Efficiency.
Chapter 11 is not adopted in California. See California Energy Code, Title 24, Part 6.
Chapter 12 Mechanical Administration.
Chapter 12 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 13 General Mechanical System Requirements.
Chapter 13 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 14 Heating and Cooling Equipment and Appliances.
Chapter 14 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 15 Exhaust Systems.
Chapter 15 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 16 Duct Systems.
Chapter 16 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 17 Combustion Air.
Chapter 17 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 18 Chimneys and Vents.
Chapter 18 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 19 Special Appliances, Equipment and Systems.
Chapter 19 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 20 Boilers and Water Heaters.
Chapter 20 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
xvi 2025 CALIFORNIA RESIDENTIAL CODE
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Chapter 21 Hydronic Piping.
Chapter 21 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 22 Special Piping and Storage Systems.
Chapter 22 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 23 Solar Thermal Energy Systems.
CRC § 402.1. Medium relevance — show source text
Ra = outdoor airflow rate required per unit area (CFM/ft [2] )
[(L/s)/m [2] ] in accordance with Table 402.1.
Ez = zone air distribution effectiveness in accordance with Table 403.2.2. For SI units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.00047 m [3] /s,
1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per minute per square foot
= 5.08 [(L/s)/m [2] ]
RpPz + RaAz Vot = Ez
5 x 100 + 0.06 x 2000
= 1.0
2025 CALIFORNIA MECHANICAL CODE 547
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548 2025 CALIFORNIA MECHANICAL CODE
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CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE
APPENDIX H – PROFESSIONAL QUALIFICATIONS
(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-
CGSFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC Adopting Agency BSC BSC-
CGSFM 1 2 1-AC AC ** SS** ** SS/CC** 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6 Adopt Entire Chapter Adopt Entire Chapter as
amended (amended sections
listed below)Adopt only those sections
that are listed belowChapter/Section This state agency does not adopt sections identified with the following symbol: 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.
2025 CALIFORNIA MECHANICAL CODE 549
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550 2025 CALIFORNIA MECHANICAL CODE
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APPENDIX H
CRC § 1.12.0 Medium relevance — show source text
1.12.0 Reserved for the State Librarian.
1.13.0 Reserved for the Department of Water Resources.
1.14.0 Reserved for the State Lands Commission.
2025 CALIFORNIA MECHANICAL CODE 19
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DIVISION II
SCOPE AND ADMINISTRATION
101.0 General.
101.1 Title. This document shall be known as the “Uniform Mechanical Code,” may be cited as such, and will be referred to herein as “this code.”
101.2 Scope. The provisions of this code shall apply to the erection, installation, alteration, repair, relocation, replacement, addition to, use, or maintenance of mechanical systems within this jurisdiction.
101.3 Purpose. This code is an ordinance providing minimum requirements and standards for the protection of the public health, safety, and welfare.
101.4 Unconstitutional. Where a section, subsection, sentence, clause, or phrase of this code is, for a reason, held to be unconstitutional, such decision shall not affect the validity of the remaining portions of this code. The legislative body hereby declares that it would have passed this code, and each section, subsection, sentence, clause, or phrase thereof, irrespective of the fact that one or more sections, subsections, sentences, clauses, and phrases are declared unconstitutional.
101.5 Validity. Where a provision of this code, or the application thereof to a person or circumstance, is held invalid, the remainder of the code, or the application of such provision to other persons or circumstances, shall not be affected thereby.
102.0 Applicability. 102.1 Conflicts Between Codes. Where the requirements within the jurisdiction of this mechanical code conflict with the requirements of the plumbing code, the plumbing code shall prevail. In instances where this code, applicable standards, or the manufacturer’s installation instructions conflict, the more stringent provisions shall prevail. Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall prevail. [OSHPD 1, 1R, 2, 3, 4 & 5] See Chapter 1, Division I, Section 1.1.7
102.2 Existing Installations. Mechanical systems lawfully in existence at the time of the adoption of this code shall be permitted to have their use, maintenance, or repair continued where the use, maintenance, or repair is in accordance with the original design and location and no hazard to life, health, or property has been created by such mechanical system.
102.3 Maintenance. Mechanical systems, materials, and appurtenances, both existing and new, of a premise under the Authority Having Jurisdiction shall be maintained in operating condition. Devices or safeguards required by this code shall be maintained in accordance with the code edition under
which installed.
The owner or the owner’s designated agent shall be responsible for maintenance of mechanical systems. To determine compliance with this subsection, the Authority Having Jurisdiction shall be permitted to cause a mechanical system to be reinspected.
**102.3.1 Commercial HVAC Systems.
Frequently asked questions
Can I run PVC regulator vent piping through an attic to a rooftop terminus?
No. PVC vent piping shall not be installed indoors; attic runs are considered interior and are not permitted. Use allowed materials and route the vent outdoors without passing through occupied interior spaces. § 1308.4.4.1
Is a listed regulator with a vent limiting device required to be vented to the outdoors?
Not necessarily — a listed regulator + vent limiting means combination complying with CSA/ANSI Z21.80/CSA 6.22 is not required to be vented to the outdoors per the code exception. § 1308.4 (exceptions)
How close can a vent terminus be to a building opening or ignition source?
Vents must terminate not less than 3 ft (914 mm) from a possible source of ignition. Other local or utility rules may require larger clearances for specific openings (check local and utility requirements). § 1308.4
Can multiple regulator vents be manifolded together?
The code prohibits connecting vent piping from pressure regulators and gas pressure controls to a common manifold that serves a bleed line from a diaphragm-type gas valve. § 1308.4
What if the vent terminus may be submerged by floodwater?
Install an antiflood-type breather vent fitting or locate the vent terminus above the height of expected floodwaters or snow. § 1308.4
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