CRC · California Residential Code

Venting methods and vent sizing

Q: Do I always have to upsizing a vent if I run it horizontally?

Not always. Horizontal runs on a minimum‑sized vent are limited to one‑third of the vent’s permitted length from the sizing table. If you exceed that, either upsized the vent one full pipe size for its entire length or reroute vertically — § 904.2 .

Q: What is the smallest vent I can use for a single sink?

An individual vent must be at least 1 1/4 inches and not less than one‑half the diameter of the drain it serves; however, final selection must be verified against the sizing table (Table 703.2) and length — § 904.1 .

Q: How close to the trap flood rim must a vent rise before I offset it?

Each vent (or branch vent) must rise at least 6 inches (152 mm) above the fixture flood‑level rim before any horizontal offset or connection to another vent — § 905.3 .

Q: Are the vent material standards different from drain materials?

Vent materials and fittings must meet the applicable referenced standards (see the code Table references); follow § 903.1 for the materials requirements and the code’s referenced standards tables.

Every plumbing trap must be vented so air can circulate and prevent trap siphonage; vent diameters are chosen from the fixture‑unit vs. length tables (Table 703.2), but an individual vent may never be smaller than 1 1/4 in and no less than half the drain diameter. Horizontal runs on a minimum‑sized vent are limited to one‑third of the permitted length, and vents must rise at least 6 inches above the fixture flood rim before a horizontal offset. See § 901.2, § 904.1 and § 904.2 for the controlling rules.

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Last reviewed: July 6, 2026

What the code requires — plain English (controlling §)

Every trap must be protected from siphonage and backpressure by a vent system — § 901.2.
Vent sizes are chosen from the fixture-unit/length tables; an individual vent may not be smaller than 1 1/4 inches (and must be at least one-half the diameter of the drain it serves) — § 904.1.

Every fixture trap (unless an explicit exception applies) needs a vent-sized and routed so the trap seal is maintained and air can circulate through the drainage system (see § 901.2).

Requirements in detail

1) Which fixtures must be vented

“Each plumbing fixture trap” must be vented except where the code specifically allows omission (exceptions in Chapter 9) — § 901.2.
Limited exceptions include some interceptors and certain sinks in bars/counters where venting is physically impossible — § 902.1 and § 902.2.

2) Performance limits for the vent system

Trap-seal protection: vents must be designed so a trap seal is not exposed to a pressure differential greater than 1 inch water column (0.24 kPa) on the trap outlet side — § 901.3.

3) Materials and fittings

Vent pipe and fittings must comply with the applicable standards referenced in the code (see the materials section for venting) — § 903.1.
Changes in direction must use approved fittings; piping shall not be strained or bent — § 903.3.

4) How vent size is determined

Rule: Size vents from the total fixture units served and the vent length using the drainage/vent sizing tables (refer to Table 703.2) — § 904.1.
Minimum: an individual vent diameter must be at least 1 1/4 inches (32 mm) and not less than one‑half the diameter of the drain it serves — § 904.1.

5) Limits on horizontal venting (length)

For a minimum-sized vent, no more than one‑third of its total permitted length (per the sizing table) may be horizontal; if you increase the vent one pipe size for its entire length the limit does not apply — § 904.2.

6) Rise, grade and connections

Vent and branch vents must be free from sags and be pitched or arranged so condensate/drips return to the drain they serve — § 905.1.
Each vent must rise vertically to at least 6 inches (152 mm) above the flood‑level rim of the fixture served before offsetting horizontally; where vents join, each must rise at least 6 inches above its fixture’s flood rim prior to connection — § 905.3.

Key decision dimensions/values (quick reference)

Decision / dimension	Value / threshold	Code Reference
Trap venting required	Every trap (unless exception)	§ 901.2
Trap-seal pressure limit	1 inch water column (0.24 kPa)	§ 901.3
Minimum individual vent diameter	1 1/4 in (32 mm); ≥ ½ drain diameter	§ 904.1
Sizing method	By total fixture units and vent length per Table 703.2	§ 904.1
Horizontal portion limit (min‑sized vents)	≤ 1/3 of permitted length (per table)	§ 904.2
Minimum rise before offset or connection	6 in (152 mm) above flood rim	§ 905.3
Materials & fittings	Must meet referenced standards (Table 701.2)	§ 903.1

Note: The code directs you to sizing tables (for example Table 703.2) rather than listing all diameters inline; use the table plus the rules above to pick the correct vent diameter and allowable length.

Exceptions & special cases

Interceptor outlet vents can be omitted when the interceptor discharges indirectly into a second, trapped and vented interceptor — § 902.1.
Sinks integral to bars/counters that cannot practically be vented may discharge through an approved indirect waste to a receptor instead of being vented — § 902.2.
If a minimum-sized vent is upsized one pipe size for its entire length, the horizontal-length limitation in § 904.2 does not apply (use that option where long horizontal runs are unavoidable).
Gas appliance vents and chimneys are sized under other provisions (see the plumbing code sections for fuel‑burning appliance venting and the Mechanical Code); those requirements are separate from plumbing drainage vents. The plumbing/mechanical venting sections contain specific tables and rules for gas vents and chimneys.

If your question requires a vent to serve fixtures upstream of pumps/ejectors/backwater valves, note the vent pipe from those fixtures cannot be counted toward the building‑sewer cross‑sectional vent area requirement (see § 904.1).

Common mistakes

Relying on a remembered minimum diameter instead of consulting Table 703.2 for the actual fixture‑unit/length combination — the code requires table‑based sizing, not guesswork (§ 904.1).
Installing long horizontal runs on a minimum‑sized vent that exceed one‑third of the permitted length — this violates § 904.2.
Offsetting or tying vents lower than 6 inches above the fixture flood rim before the required vertical rise — violates § 905.3 and can allow trap purge or trap seal loss.
Using an undersized vent smaller than ½ the drain diameter or less than 1 1/4 in without performing the table lookup and justification — see § 904.1.
Confusing plumbing drainage vents (Chapter 9) with gas appliance vents / chimneys — these are governed by different sections and different sizing tables.

Worked example — method (concrete scenario)

Scenario: A small bathroom branch includes a lavatory (1 DFU), bathtub (2 DFU), and a shower (2 DFU) — total = 5 fixture units. The horizontal distance to the vent attachment point and total vent rise give an effective vent length.

Step 1 — Count fixture units: lavatory (1) + tub (2) + shower (2) = 5 DFU.

Step 2 — Measure the vent “length” per the sizing rules (the code’s sizing table instructions define how to count length and elevations; consult Table 703.2). Use the total DFU and the vent length to read the required vent diameter from Table 703.2 — § 904.1.

Step 3 — Check minimums: even if the table gave a very small size, the vent must be at least 1 1/4 in and no less than ½ the drain diameter — § 904.1.

Step 4 — Check horizontal limit: if your selected vent is the minimum size and you have horizontal routing, ensure horizontal length ≤ 1/3 of permitted length per table; otherwise upsize the vent one pipe size for the entire run or reroute — § 904.2.

(Important: I did not reproduce Table 703.2 here. To complete the numeric selection you must consult Table 703.2 in the code and follow its length‑and‑DFU lookup; the code text requires using that table for vent sizing.)

Related provisions (useful nearby sections)

§ 901.1 — Applicability (Chapter 9 scope).
§ 901.3 — Trap seal protection limit (1 in water column).
§ 902.1 – § 902.2 — Vents not required (interceptors, special sinks).
§ 903.1 – § 903.3 — Materials and changes in direction for vents.
§ 904.1 – § 904.2 — Size and length rules for vents (Table 703.2 referenced).
§ 905.1 – § 905.3 — Vent grades, connections, and required rise before offsets.
Appendix/Tabular resources: Table 703.2 (fixture units × length sizing) and Appendix C sizing tables (see code tables).

Code references

Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:

CPC § 2025 High relevance — show source text
Chapter 7 Sanitary Drainage.

This chapter regulates the design and installation of sanitary drainage systems to ensure they will work as intended. Drainage piping should not be oversized nor undersized, and constructed of approved materials to guard against fouling, deposit of solids, clogging, and with cleanouts so arranged that the pipes may be readily cleaned. The purpose of the sanitary drainage system is to remove effluent discharged from plumbing fixtures and other equipment to an approved point of disposal, such as a public sanitary system or private sewage disposal system.

The basics of a sanitary drainage system include public and private sewage disposal; selection of materials; installation of the building drain and sewer; joining methods for pipe and fittings; drainage fixture units for sizing the drainage system; sumps and ejectors; vent sizing and length of vents; and testing.

Chapter 8 Indirect Wastes.

Chapter 8 regulates indirect waste connections that are required for plumbing fixtures and plumbing appliances dealing with food preparation, dishwashing, potable liquids, and similar equipment. An indirect connection prevents sewage from backing up into a fixture or appliance, thus providing protection against potential health hazards. The waste pipe discharges through an air gap or air break into a waste receptor or standpipe. The protection in the form of an air gap is necessary when the contamination is a potential health hazard or cross connection with the potable water system. Where there is no possibility of contaminating the potable water (nonpotable discharge), the indirect waste pipe may connect in the form of an air break. This method is often preferred to prevent splashing. In addition, health care facilities and special wastes must be protected from contamination that may result from the connection to the drainage system. The waste must be treated to prevent any damage to the piping or sewage treatment process. Waste receptors are sized and designed to prevent splashing and allow for peak discharge conditions.

Chapter 9 Vents.

Chapter 9 regulates the material, design, and installation of vents. A vent system is a pipe or pipes installed in a drainage system that provide a flow of air to and from the system to ventilate it, provide a circulation of air to eliminate trap siphonage, and reduce back-pressure and vacuum surge. In addition, vents provide the rapid and silent flow of waste without exposing occupants of the building to any sewer gases. Proper installation of vents is crucial, as a telltale sign that there is a problem in the drain and vent system is related to the elevation of the horizontal portion of the venting. Venting is not limited to sanitary drainage systems. Venting methods are applicable to other drainage systems such as those for chemical waste, graywater waste, and clear water waste. Sizing the venting system is directly tied to the design of the drainage system. For example, the velocities in the drainage system and its peak flow rates affect the diameters in the venting system. Where the vertical distance between a fixture outlet and trap is excessive, velocities in the entire drainage system will be greater than those in the vent sizing table. All venting methods in this chapter are categorized as either dry vents or wet vents. Vent stacks, stack vents, branch vents, island vents, relief vents, and individual vents are dry vents. Wet vents (horizontal or vertical), circuit vents, combination drain and vents are versions of “wet venting” in which the vent is wetted by drainage flow.

2025 CALIFORNIA PLUMBING CODE xv
CPC § 2025 High relevance — show source text
The waste must be treated to prevent any damage to the piping or sewage treatment process. Waste receptors are sized and designed to prevent splashing and allow for peak discharge conditions.

Chapter 9 Vents.

Chapter 9 regulates the material, design, and installation of vents. A vent system is a pipe or pipes installed in a drainage system that provide a flow of air to and from the system to ventilate it, provide a circulation of air to eliminate trap siphonage, and reduce back-pressure and vacuum surge. In addition, vents provide the rapid and silent flow of waste without exposing occupants of the building to any sewer gases. Proper installation of vents is crucial, as a telltale sign that there is a problem in the drain and vent system is related to the elevation of the horizontal portion of the venting. Venting is not limited to sanitary drainage systems. Venting methods are applicable to other drainage systems such as those for chemical waste, graywater waste, and clear water waste. Sizing the venting system is directly tied to the design of the drainage system. For example, the velocities in the drainage system and its peak flow rates affect the diameters in the venting system. Where the vertical distance between a fixture outlet and trap is excessive, velocities in the entire drainage system will be greater than those in the vent sizing table. All venting methods in this chapter are categorized as either dry vents or wet vents. Vent stacks, stack vents, branch vents, island vents, relief vents, and individual vents are dry vents. Wet vents (horizontal or vertical), circuit vents, combination drain and vents are versions of “wet venting” in which the vent is wetted by drainage flow.

2025 CALIFORNIA PLUMBING CODE xv

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FORMAT OF THE UNIFORM PLUMBING CODE

Chapter 10 Traps and Interceptors.

Chapter 10 regulates the material, design, and installation of traps, interceptors, and separators. Traps are required on drainage type plumbing fixtures and must be self-scouring without interior partitions. Interceptors, on the other hand, are designed to control what goes down a drain. Interceptors are used to keep harmful substances from entering the sanitary drainage system, such as grease, sand, oil and other materials. The retained materials need periodic removal to maintain efficiency and function of the separating device. The capacity of an interceptor is based on retention and flow rate. There are many types of interceptors that are used at beauty salons, hospitals, meat, fish or foul packaging, refineries, repair garages, gas stations, car washing facilities, various plants, factories, and processing sites. The designer of the building is responsible for locating interceptors with the expectation for the frequency of maintenance, ease of cleaning and floor space for equipment.

Chapter 11 Storm Drainage.

Chapter 11 regulates the removal of stormwater from roofs, yards, paved areas, and similar areas. The objective of storm drainage systems is to provide a conduit or channel through which runoff will be carried from a point of collection to a point of disposal; this protects the property and the public from the uncontrolled flow of runoff and ensures that drains and inlets are adequately sized to receive the volume of runoff that flows to the drains. For the purpose of system design, it’s necessary to specify the duration of a selected storm.
CRC § 12.7.4.1 High relevance — show source text
(4) For sizing a gas vent connected to two appliances with draft hoods, the effective area of the vent shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet or greater than seven times the smaller draft hood outlet area.

(5) Engineering methods. [NFPA 54:12.7.4.1] 509.6.2.2 Vent Offsets. Type B and Type L vents sized in accordance with Section 509.6.2.1(3) or Section 509.6.2.1(4) shall extend in a generally vertical direction with offsets not exceeding 45 degrees (0.79 rad), except that a vent system having not more than one 60 degree (1.05 rad) offset shall be permitted. Any angle greater than 45 degrees (0.79 rad) from the vertical is considered horizontal. The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall not be greater than 75 percent of the vertical height of the vent. [NFPA 54:12.7.4.2] 509.6.2.3 Category II, Category III, and Cate- gory IV Appliances. The sizing of gas vents for Category II, Category III, and Category IV appliances shall be in accordance with the appliance manufacturers’ instructions. The sizing of plastic pipe specified by the appliance manufacturer as a venting material for Category II, III, and IV appliances shall be in accordance with the appliance manufacturers’ instructions. [NFPA 54:12.7.4.3] 509.6.2.4 Sizing. Chimney venting systems using mechanical draft shall be sized in accordance with engineering methods. [NFPA 54:12.7.4.4] 509.6.3 Gas Vents Serving Appliances on More than One Floor. Where a common vent is installed in a multistory installation to vent Category I appliances located on more than one floor level, the venting system shall be designed and installed in accordance with engineering methods. Crawl spaces, basements, and attics shall be considered as floor levels. [NFPA 54:12.7.5.1]

509.6.3.1 Occupiable Space. All appliances connected to the common vent shall be located in rooms separated from occupiable space. Each of these rooms shall have provisions for an adequate supply of combustion, ventilation, and dilution air that is not supplied from occupiable space. [NFPA 54:12.7.5.2] (See Figure 509.6.3.1)

FIGURE 509.6.3.1

PLAN VIEW OF PRACTICAL SEPARATION

METHOD FOR MULTISTORY GAS VENTING

[NFPA 54: FIGURE A.12.7.5.2]

509.6.3.2 Multistory Venting System. The size of the connectors and common segments of multistory venting systems for appliances listed for use with a Type B double-wall gas vent shall be in accordance with Table 510.2(1), provided all of the following apply:

(1) The available total height ( H ) for each segment of a multistory venting system is the vertical distance between the level of the highest draft hood outlet or flue collar on that floor and the centerline of the next highest interconnection

tee.

CRC § 1.0 High relevance — show source text

ROOF SLOPE	H (minimum) (feet)
Flat to6⁄12	1.0
Over6⁄12 to7⁄12	1.25
Over7⁄12 to8⁄12	1.5
Over8⁄12 to9⁄12	2.0
Over9⁄12 to10⁄12	2.5
Over10⁄12 to11⁄12	3.25
Over11⁄12 to12⁄12	4.0
Over12⁄12 to14⁄12	5.0
Over14⁄12 to16⁄12	6.0
Over16⁄12 to18⁄12	7.0
Over18⁄12 to20⁄12	7.5
Over20⁄12 to21⁄12	8.0

For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm

802.6.1.1 Insulation Protection Shield. Where a vent passes through an insulated assembly, an approved metal shield constructed of steel having a thickness of not less than 0.0179 inch (0.45 mm) (26 gauge) shall be installed between the vent and insulation. The shield shall extend not less than 2 inches (51 mm) above the insulation and be secured to the structure in accordance with the manufacturer’s

installation instructions.

802.6.2 Size of Gas Vents. Venting systems shall be sized and constructed in accordance with Section 802.6.2.1 through Section 802.6.2.3 and the appliance manufacturer’s instructions. [NFPA 54:12.7.4] 802.6.2.1 Category I Appliances. The sizing of natural draft venting systems serving one or more listed appliances equipped with a draft hood or appliances listed for use with a Type B gas vent, installed in a single story of a building, shall be in accordance with one of the following: (1) The provisions of Section 803.0. (2) Vents serving fan-assisted combustion system appliances, or combinations of fan-assisted combustion system and draft hood-equipped appliances, shall be sized in accordance with Section 803.0 or other engineering methods. (3) For sizing an individual gas vent for a single, draft hood-equipped appliance, the effective area of the vent connector and the gas vent shall be not less than the area of the appliance draft hood outlet or greater than seven times the draft hood outlet area.

(4) For sizing a gas vent connected to two appliances with draft hoods, the effective area of the vent shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet or greater than seven times the smaller draft hood outlet area.

(5) Engineering methods. [NFPA 54:12.7.4.1]

**802.6.2.2 Vent Offsets.

CRC § 0.79 High relevance — show source text
Any angle greater than 45 degrees (0.79 rad) from the vertical is considered horizontal. The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall not be greater than 75 percent of the vertical height of the vent. [NFPA 54:12.7.4.2] 802.6.2.3 Category II, Category III, and Cate- gory IV Appliances. The sizing of gas vents for Category II, Category III, and Category IV appliances shall be in accordance with the appliance manufacturers’ instructions. The sizing of plastic pipe specified by the appliance manufacturer as a venting material for Category II, III, and IV appliances shall be in accordance with the appliance manufacturers’ instructions. [NFPA 54:12.7.4.3] 802.6.2.4 Sizing. Chimney venting systems using mechanical draft shall be sized in accordance with engineering methods. [NFPA 54:12.7.4.4] 802.6.3 Gas Vents Serving Appliances on More than One Floor. Where a common vent is installed in a multistory installation to vent Category I appliances located on more than one floor level, the venting system shall be designed and installed in accordance with engineering methods.

Crawl spaces, basements, and attics shall be considered as floor levels. [NFPA 54:12.7.5.1] 802.6.3.1 Occupiable Space. All appliances connected to the common vent shall be located in rooms separated from occupiable space. Each of these rooms shall have provisions for an adequate supply of combustion, ventilation, and dilution air that is not supplied from occupiable space. [NFPA 54:12.7.5.2] (See Figure 802.6.3.1) 802.6.3.2 Multistory Venting System. The size of the connectors and common segments of multistory venting systems for appliances listed for use with a Type B double-wall gas vent shall be in accordance with Table 803.2(1), provided all of the following apply: (1) The available total height ( H ) for each segment of a multistory venting system is the vertical distance between the level of the highest draft hood outlet or flue collar on that floor and the centerline of the next highest interconnection tee. (2) The size of the connector for a segment is determined from the appliance’s gas input rate and available connector rise and shall not be smaller

than the draft hood outlet or flue collar size.

(3) The size of the common vertical vent segment, and of the interconnection tee at the base of that segment, is based on the total appliance’s gas input rate entering that segment and its available total height. [NFPA 54:12.7.5.3]

158 2025 CALIFORNIA MECHANICAL CODE

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CHIMNEYS AND VENTS

FIGURE 802.6.3.1

PLAN VIEW OF PRACTICAL SEPARATION METHOD

FOR MULTISTORY GAS VENTING

[NFPA 54: FIGURE A.12.7.5.2]

802.6.4 Support of Gas Vents. Gas vents shall be supported and spaced in accordance with the manufacturer’s installation instructions. [NFPA 54:12.7.6]
CRC § 12.14.1 High relevance — show source text
placing the appliance in service. Balancing baffles shall be listed in accordance with UL 378. [NFPA 54:12.14.1 – 12.14.3]

802.14 Automatically Operated Vent Dampers. An automatically operated vent damper shall be listed. [NFPA 54:12.15]

802.14.1 Listing. Automatically operated vent dampers for oil-fired appliances shall comply with UL 17. The automatic damper control shall comply with UL 378.

802.15 Obstruction of Flow. Devices that retard the flow of vent gases shall not be installed in a vent connector, chimney, or vent. The following shall not be considered as obstructions:

(1) Draft regulators and safety controls specifically listed for installation in venting systems and installed in accordance with the manufacturer’s installation instructions.

(2) Approved draft regulators and safety controls designed and installed in accordance with engineering methods.

(3) Listed heat reclaimers and automatically operated vent dampers installed in accordance with the manufacturers’ installation instructions.

(4) Vent dampers serving listed appliances installed in accordance with Section 803.1 or Section 803.2 or engineering methods.

(5) Approved economizers, heat reclaimers, and recuperators installed in venting systems of appliances not required to be equipped with draft hoods, provided the appliance manufacturer’s instructions cover the installation of such a device in the venting system and performance in accordance with Section 802.3 and Section

802.3.1 is obtained. [NFPA 54:12.16]

803.0 Sizing of Category I Venting Systems.

803.1 Additional Requirements to Single Appliance Vent. Venting Table 803.1.2(1) through Table 803.1.2(6) shall not be used where obstructions are installed in the venting system. The installation of vents serving listed appliances with vent dampers shall be in accordance with the appliance manufacturer’s instructions or in accordance with the following:

(1) The maximum capacity of the vent system shall be determined using the “NAT Max” column.

(2) The minimum capacity shall be determined as though the appliance were a fan-assisted appliance, using the “FAN Min” column to determine the minimum capacity of the vent system. Where the corresponding “FAN Min” is “NA,” the vent configuration shall not be permitted and an alternative venting configuration shall be utilized.

[NFPA 54:13.1.1]

803.1.1 Vent Downsizing. Where the vent size determined from the tables is smaller than the appliance draft hood outlet or flue collar, the use of the smaller size shall be permitted, provided that the installation complies with all of the following requirements:

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«

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2025 CALIFORNIA MECHANICAL CODE 165

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CHIMNEYS AND VENTS

(1) The total vent height ( H ) is at least 10 feet (3048 mm).

(2) Vents for appliance draft hood outlets or flue collars 12 inches (305mm) in diameter or smaller are not reduced more than one table size.

(3) Vents for appliance draft hood outlets or flue collars larger than 12 inches (305 mm) in diameter are not reduced more than two table sizes.
CRC § 802.1 Medium relevance — show source text
802.1 Listing . . . . . . . . . . . . . . . . . . . . . . 153

802.2 Connection to Venting Systems . . 153

802.3 Minimum Safe Performance . . . . . 153

802.4 Type of Venting System to be Used . . . . . . . . . . . . . . . . . . . . . . . 154

802.5 Masonry, Metal, and Factory-Built Chimneys . . . . . . . . . . . . . . . . . . . 154

Table 802.4 Type of Venting System to be Used . . . . . . . . . . . . . . . . . . . . . . . 155

802.6 Gas Vents. . . . . . . . . . . . . . . . . . . 157

Table 802.6.1 Roof Slope Heights. . . . . . . . . . . . 158

802.7 Single-Wall Metal Pipe . . . . . . . . . 159

Table 802.7.3.3 Clearance for Connectors. . . . . . . 160

802.8 Through-the-Wall Vent Termination . . . . . . . . . . . . . . . . . . 160

802.9 Condensation Drain . . . . . . . . . . . 160

802.10 Vent Connectors for Category I Appliances . . . . . . . . . . . . . . . . . . 160

Table 802.10.1.3 Minimum Thickness for Galvanized

Steel Vent Connectors for Low Heat Appliances . . . . . . . . . . . . . . 161

Table 802.10.1.4 Minimum Thickness for Steel

Vent Connectors for Medium Heat Appliances . . . . . . . . . . . . . . 161

Table 802.8.1 Through-the-Wall Direct Vent Termination Clearances . . . . . . . . 162

802.11 Vent Connectors for Category II, Category III, and Category IV Appliances . . . . . . . . . . . . . . . . . . 164

802.12 Appliances Requiring Draft Hoods . . . . . . . . . . . . . . . . . . 164

802.13 Manually Operated Dampers . . . . 165

802.14 Automatically Operated Vent Dampers . . . . . . . . . . . . . . . . . . . . 165

802.15 Obstruction of Flow. . . . . . . . . . . . 165

803.0 Sizing of Category I Venting Systems . . . . . . . . . . . . . . . . . . . . 165

803.1 Additional Requirements to Single Appliance Vent . . . . . . . . . 165

803.2 Additional Requirements to Multiple-Appliance Vent.. . . . . . . . 167

Table 803.2.1 Vent Connector Maximum

Length. . . . . . . . . . . . . . . . . . . . . . 167

Table 803.1.2(1) Type B Double-Wall Gas Vent . . . 172

Table 803.1.2(2) Type B Double-Wall Gas Vent . . . 175
CMC § 2025 Medium relevance — show source text
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.

Chapter 9 Installation of Specific Appliances. Chapter 9 regulates the minimum requirements for the design, construction and installation of specific appliances. The provisions address the minimum requirements for gas-fired appliances, oil-fired appliances, wood-fired appliances, and electric-type appliances. In addition to the requirements of this chapter, appliances are also required to comply with the general requirements of Chapter 3.

Chapter 10 Boilers and Pressure Vessels. Chapter 10 regulates the construction, installation, operation, repair, and alteration of boilers and pressure vessels. The safety provisions within this chapter address controls and limit devices for automatic boilers, methods of determining expansion tank capacities, discharge piping, relief valves, shutoff valves, gas-pressure and combustion regulators, and inspections and tests. Potable water heaters are free from the requirements of Chapter 10 as they are within the scope of the Uniform Plumbing Code (UPC).

Pressure vessels store large amounts of energy and must comply with ASME Boiler and Pressure Vessel Code (BPVC) Section VIII.1. The stored energy must be contained to prevent disastrous failures. Boilers must comply with ASME BPVC Section I, ASME BPVC Section IV, or NFPA 85. Installing a safety relief valve and expansion tank prevents pressures in the tank from exceeding the design threshold.

Chapter 11 Refrigeration. Chapter 11 regulates the design, installation, and construction requirements of refrigeration systems and the installation and construction of cooling towers. Refrigeration is a method used for achieving heat transfer to cool spaces. Refrigerants are the most common medium used to transfer the heat energy from the low-temperature level to the high-temperature level. Table

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FORMAT OF THE UNIFORM MECHANICAL CODE
CPC § 2025 Medium relevance — show source text
Appendix A Recommended Rules for Sizing the Water Supply System.

Appendix A provides a method of sizing the water supply and distribution system that provides precise calculations to establish the proper pressures and flow to the system’s fixtures. The goal of sizing the system is to deliver an acceptable volume of water to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; provide satisfactory water pressure to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; and to prevent excessive water velocity during maximum flow conditions.

Appendix B Explanatory Notes on Combination Waste and Vent Systems.

Appendix B contains general guidelines for the design and installation of combination waste and vent systems. These systems are designed for waste piping and are purposely oversized to serve as both a waste and vent pipe to avoid excessive pneumatic effects at fixture drains.

Appendix C Alternate Plumbing Systems.

The intent of this appendix is to provide clarification of procedures for the design and approval of engineered plumbing systems, alternate materials, and equipment that are not specifically covered in other parts of the code. Alternative methods are allowed to be used where approved by the authority having jurisdiction. Approval of alternatives is based on a demonstration showing that the method or material used is at least equivalent in strength, deflection, and capacity to that provided by the prescriptive methods and materials.

Appendix D Sizing Storm Water Drainage Systems.

Appendix D provides general guidelines for the sizing of stormwater drainage systems. There are two pieces of information that must always be a given. They are the roof size and the rate of rainfall for the area.

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FORMAT OF THE UNIFORM PLUMBING CODE

Appendix E Manufactured/Mobile Home Parks and Recreational Vehicle Parks.

The provisions of this appendix apply to the plumbing and drainage systems of mobile home and recreational vehicle parks. These provisions also apply to the use, maintenance, and installation for supplying fuel gas, water, electricity, and disposal of sewage from accessory buildings or structures, and building components.

Appendix F Firefighter Breathing Air Replenishment Systems.

Appendix F provides guidance on installing firefighter breathing air replenishment systems. System components include outside fire department connection panel, interior air fill panel or station, interconnected piping distribution system and pressure monitoring switch. Fire departments access the system through an outside connection panel and are able to pump air into the system. The firefighters inside the structure access the system at fill stations that are found throughout the building. The piping distribution system is made from stainless tubing or other approved materials. It delivers compressed air to the building’s interior air-fill stations and interior air-fill panels. The tubing also acts as a conduit in the interior of the building between the outside connection panel and the air storage system. If the system becomes over-pressurized, the air monitoring system also acts as a pressure relief. A system isolation valve is placed alongside each interior air fill station and interior air fill panel to isolate the system.

Appendix G Sizing of Venting Systems.

Appendix G provides added information on the sizing of gas vents. This appendix is useful to the end user for the proper sizing of venting systems. A series of examples are given that show how to use the tables and other requirements of Chapter 5.

Appendix H Private Sewage Disposal Systems.
CRC § 10-8 Medium relevance — show source text
000|10-8|12-6|9-8|10-0|9-0|8-2|7-7|6-4|6-2| |24|2-#4
1-#6|60,000|12-11|15-2|11-9|12-2|11-0|9-11|9-3|7-8|7-6| |24|2-#5|40,000|15-2|17-9|13-9|14-3|12-10|11-7|10-10|9-0|8-9| |24|2-#5|60,000|18-4|21-6|16-7|17-3|15-6|14-0|13-1|10-4|10-0| |24|2-#6|40,000|18-0|21-1|16-4|16-11|14-10|12-9|11-8|9-2|8-11| |24|2-#6|60,000|21-7|25-4|19-2|20-4|17-2|14-9|13-4|10-4|10-0| |24|Center distance_A_k, l|Center distance_A_k, l|4-6|6-2|3-8|4-0|3-3|2-8|2-3|1-7|1-6| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 pound per square foot = 0.0479 kPa, Grade 40 = 280 MPa, Grade 60 = 420 MPa.
a. See Table R608.3 for tolerances permitted from nominal thickness.
b. Table values are based on concrete with a minimum specified compressive strength of 2,500 psi. See Note j.
c. Table values are based on uniform loading. See Section R608.8.2 for lintels supporting concentrated loads.
d. Deflection criterion is_L_/240, where_L_ is the clear span of the lintel in inches, or1/2 inch, whichever is less.
e. Linear interpolation is permitted between ground snow loads and between lintel depths.
f. DR indicates design required.
g. Lintel depth,D, is permitted to include the available height of wall located directly above the lintel, provided that the increased lintel depth spans the entire length of the
lintel.
h. Stirrups shall be fabricated from reinforcing bars with the same yield strength as that used for the main longitudinal reinforcement.
i. Allowable clear span without stirrups applicable to all lintels of the same depth,D. Top and bottom reinforcement for lintels without stirrups shall be not less than the least
amount of reinforcement required for a lintel of the same depth and loading condition with stirrups. All other spans require stirrups spaced at not more than_d_/2.
j. Where concrete with a minimum specified compressive strength of 3,000 psi is used, clear spans for lintels without stirrups shall be permitted to be multiplied by 1.05.
CRC § 7-11 Medium relevance — show source text
000|7-11|9-0|6-11|7-2|6-5|6-0|5-7|4-8|4-7| |24wj|1-#4|60,000|9-8|10-11|8-5|8-9|7-10|7-4|6-10|5-9|5-7| |24wj|1-#5|40,000|9-10|11-2|8-7|8-11|8-0|7-6|7-0|5-10|5-8| |24wj|1-#5|60,000|12-0|13-7|10-6|10-10|9-9|9-2|8-6|7-2|6-11| |24wj|2-#4
1-#6|40,000|11-1|12-7|9-8|10-1|9-1|8-6|7-10|6-7|6-5| |24wj|2-#4
1-#6|60,000|15-6|17-7|13-6|14-0|12-8|11-10|10-8|8-7|8-4| |24wj|2-#5|40,000|15-6|17-11|12-8|13-4|11-6|10-7|9-7|7-10|7-7| |24wj|2-#5|60,000|DR|DR|DR|DR|DR|DR|DR|DR|DR| |24wj|Center distance_A_m, n|Center distance_A_m, n|2-4|3-0|1-9|1-11|1-6|1-4|1-2|STL|STL| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 pound per square foot = 0.0479 kPa, Grade 40 = 280 MPa, Grade 60 = 420 MPa.
a. Where lintels are formed with waffle-grid forms, form material shall be removed, if necessary, to create top and bottom flanges of the lintel that are not less than 3 inches in
depth (in the vertical direction), are not less than 5 inches in width for 6-inch-nominal waffle-grid forms and not less than 7 inches in width for 8-inch-nominal waffle-grid
forms. See Figure R608.8(3). Flat form lintels shall be permitted in place of waffle-grid lintels. See Tables R608.8(2) through R608.8(5).
b. See Table R608.3 for tolerances permitted from nominal thicknesses and minimum dimensions and spacing of cores.
c. Table values are based on concrete with a minimum specified compressive strength of 2,500 psi. See Notes l and n. Table values are based on uniform loading. See Section
R608.8.2 for lintels supporting concentrated loads.
d. Deflection criterion is_L_/240, where_L_ is the clear span of the lintel in inches, or1/2 inch, whichever is less.
e. Linear interpolation is permitted between ground snow loads.
f. DR indicates design required. STL indicates stirrups required throughout lintel.
g.
CRC § 1.1 Medium relevance — show source text
CBC—25: California Building Code R101.2, R202, R301.1.1, R301.1.3, R301.2.1.1, R301.2.2.1.1, R301.2.2.1.2, R301.3, Table R302.1(1), Table R302.1(2), R302.2.1, R302.2.2, R302.3, R302.15.4, R322.1, R322.3, R324.5, R403.1.8, Table R602.10.3(3), Table R606.12.2.1, R609.2, R905.10.3

CEBC—25: California Existing Building Code [®]

R110.2, N1109.2

CFC—25: California Fire Code [®]

R102.6, R329.2, N1109.2, M2201.7, G2402.3, G2412.2

CWUIC—25: California Wildland-Urban Interface Code

R102.8, R337, R806.1.1, R907.1.1

ICC 400—2022: Standard on the Design and Construction of Log Structures

R301.1.1, R502.1.4, R602.1.4, R703.1, R802.1.3

ICC 500—2020: ICC/NSSA Standard for the Design and Construction of Storm Shelters

R307.1

ICC 600—2020: 2020 Standard for Residential Construction in High-Wind Regions

R301.2.1.1

ICC 1100—2019: Standard for Spray-applied Polyurethane Foam Plastic Insulation

R303.1.1

IPMC—24: International Property Maintenance Code [®]

R102.6

ISO International Organization for Standardization Chemin de Blandonnet 8 Geneva, Switzerland CP 401 - 1214

8336—2009: Fibre-cement Flat Sheets—Product Specification and Test Methods Table R503.2.1.1(1), Table R503.2.1.1(2), Table R602.3(2), Table R702.4.2, R703.10.1, R703.10.2

44-16 2025 CALIFORNIA RESIDENTIAL CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

REFERENCED STANDARDS

NFPA National Fire Protection Association 1 Batterymarch Park Quincy, MA 02169-7471

13D— 25 : Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes as amended*

R309.1.1, R309.2.1, R309.3.1, R309.3.1.1, R309.3.2.3, R309.3.6.1, R329.6.2.1

*See California Fire Code for amendments

*NFPA 13D, Amended Sections as follows:
CRC § 510.2 Medium relevance — show source text
Where singlewall and Type B double-wall metal pipes are used for vent connectors within the same venting system, the common vent shall be sized using Table 510.2(2) or Table 510.2(4) as appropriate. [NFPA 54:13.2.25] 510.2.23 Multiple Connector and Vent Sizes. Where Table 510.2(1) through Table 510.2(9) permits more than one diameter of pipe to be used for a connector or vent, all the permitted sizes shall be permitted to be used. [NFPA 54:13.2.26] 510.2.24 Interpolation. Interpolation shall be permitted in calculating capacities for vent dimensions that fall between table entries. [NFPA 54:13.2.27] 510.2.25 Extrapolation. Extrapolation beyond the table entries shall not be permitted. [NFPA 54:13.2.28] 510.2.26 Engineering Methods. For vent heights lower than 6 feet (1829 mm) and higher than shown in the tables, engineering methods shall be used to calculate vent capacities. [NFPA 54:13.2.29] 510.2.27 Height Entries. Where the actual height of a vent falls between entries in the height column of the applicable table in Table 510.2(1) through Table 510.2(9), either of the following shall be used:

(1) Interpolation.

(2) The lower appliance input rating shown in the table entries, for FAN Max and NAT Max column values; and the higher appliance input rating for the FAN Min column values. [NFPA 54:13.2.30]

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WATER HEATERS

99% Winter Design Temperatures for the Contiguous United States

This map is a necessarily generalized guide to temperatures in the contiguous United States. Temperatures shown for areas such

as mountainous regions and large urban centers are not necessarily accurate. The climate data used to develop this map are from

the ASHRAE Handbook — Fundamentals (Climate Conditions for the United States).

For 99% winter design temperatures in Alaska, consult the ASHRAE Handbook — Fundamentals.

99% winter design temperatures for Hawaii are greater than 37°F

For SI units: °C = (°F-32)/1.8

FIGURE 510.1.10

RANGE OF WINTER DESIGN TEMPERATURES USED IN ANALYZING EXTERIOR MASONRY CHIMNEYS IN THE UNITED STATES

[NFPA 54: FIGURE F.2.4]

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WATER HEATERS

|TABLE 510.1.2(1) TYPE B DOUBLE-WALL GAS VENT [NFPA|Col2|Col3|Col4|Col5|54: TABLE 13.

CRC § 12.8.4.6 Medium relevance — show source text

Exception: In lieu of thimble protection, all combustible material in the wall shall be removed a sufficient distance from the metal pipe to provide the specified clearance from such metal pipe to combustible material. Any material used to close up such opening shall be noncombustible. [NFPA 54:12.8.4.6] 509.7.3.6 Roof Thimble. Where a single-wall metal pipe passes through a roof constructed of combustible material, a noncombustible, nonventilating thimble shall be used at the point of passage. The thimble shall extend at least 18 inches (457 mm) above and 6 inches (152 mm) below the roof with the annular space open at the bottom and closed only at the top. The thimble shall be sized in accordance with Section 509.7.3.5. [NFPA 54:12.8.4.5] 509.7.4 Size of Single-Wall Metal Pipe. Single-wall metal piping shall comply with the following require ments:

(1) A venting system of a single-wall metal pipe shall be sized in accordance with one of the following methods and the appliance manufacturer’s instructions:

(a) For a draft hood-equipped appliance, in accordance with Section 510.0.

(b) For a venting system for a single appliance with a draft hood, the areas of the connector and the pipe each shall not be less than the area of the appliance flue collar or draft hood outlet, whichever is smaller. The vent area shall not be greater than seven times the draft hood outlet

area.

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WATER HEATERS

TABLE 509.7.3.4(2) REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTION [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]

Col1	[NFPA 54: TABLE 10.2.4]	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Col11
TYPE OF PROTECTION APPLIED TO AND COVERING ALL SURFACES OF COMBUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION [SEE FIGURE 509.7.3.4(1) THROUGH FIGURE 509.7.3.4(3)]	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM **APPLIANCE, VENT CONNECTOR,

CRC § 1.1 Medium relevance — show source text
1(2)_||||X||||||||||||||||||||| |903.1.1||||X|X|||||||||||||||||||| |903.1.2||||X||||||||||||||||||||| |903.1.3||||||||||X||X|X|X|X|||||||||| |906.2.1||||||||||X|X|X|X|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.

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CHAPTER 9

VENTS

901.0 General.

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.
CRC § 509.7.3.4 Medium relevance — show source text
WATER HEATERS

Notes: 1 A – Equals the clearance with no protection specified in Table 509.7.3.4(1) and Table 509.7.3.4(2) and in the sections applying to various types of equipment. 2 B – Equals the reduced clearance permitted in accordance with Table 509.7.3.4(2). 3 The protection applied to the construction using combustible material shall extend far enough in each direction to make C equal to A.

FIGURE 509.7.3.4(1) [1, 2, 3] EXTENT OF PROTECTION NECESSARY TO REDUCE CLEAR-

ANCES FROM GAS APPLIANCE OR VENT CONNECTORS

[NFPA 54: FIGURE 10.3.3.3(a)]

For SI units: 1 inch = 25.4 mm

Note: Masonry walls shall be attached to combustible walls using wall ties. Spacers shall not be used directly behind appliance or connector.

FIGURE 509.7.3.4(2) WALL PROTECTOR CLEARANCE REDUCTION SYSTEM

[NFPA 54: FIGURE 10.3.3.3(b)]

For SI units: 1 inch = 25.4 mm FIGURE 509.7.3.4(3) MASONRY CLEARANCE REDUCTION SYSTEM

[NFPA 54: FIGURE 10.3.3.3(c)]

(3) For residential and low-heat appliances, the thimble shall be a minimum of 12 inches (300 mm) larger in diameter than the metal pipe.

Exception: In lieu of thimble protection, all combustible material in the wall shall be removed a sufficient distance from the metal pipe to provide the specified clearance from such metal pipe to combustible material. Any material used to close up such opening shall be noncombustible. [NFPA 54:12.8.4.6] 509.7.3.6 Roof Thimble. Where a single-wall metal pipe passes through a roof constructed of combustible material, a noncombustible, nonventilating thimble shall be used at the point of passage. The thimble shall extend at least 18 inches (457 mm) above and 6 inches (152 mm) below the roof with the annular space open at the bottom and closed only at the top. The thimble shall be sized in accordance with Section 509.7.3.5. [NFPA 54:12.8.4.5] 509.7.4 Size of Single-Wall Metal Pipe. Single-wall metal piping shall comply with the following require ments:

(1) A venting system of a single-wall metal pipe shall be sized in accordance with one of the following methods and the appliance manufacturer’s instructions:

(a) For a draft hood-equipped appliance, in accordance with Section 510.0.

(b) For a venting system for a single appliance with a draft hood, the areas of the connector and the pipe each shall not be less than the area of the appliance flue collar or draft hood outlet, whichever is smaller. The vent area shall not be greater than seven times the draft hood outlet

area.

(c) Engineering methods.

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CRC § 25.4 Medium relevance — show source text
For SI Units: 1 inch = 25.4 mm, 1 foot = 304.8 mm

509.6.1.1 Insulation Protection Shield. Where a vent passes through an insulated assembly, an approved metal shield constructed of steel having a thickness of not less than 26 gauge (0.0179 inch) (0.45 mm) (No. 26 gauge) shall be installed between the vent and insulation. The shield shall extend not less than 2 inches (51 mm) above the insulation and be secured to the structure in accordance with the

manufacturer’s installation instructions.

509.6.2 Size of Gas Vents. Venting systems shall be sized and constructed in accordance with Section

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WATER HEATERS

509.6.2.1 through Section 509.6.2.3 and the appliance manufacturer’s instructions. [NFPA 54:12.7.4] 509.6.2.1 Category I Appliances. The sizing of natural draft venting systems serving one or more listed appliances equipped with a draft hood or appliances listed for use with a Type B gas vent, installed in a single story of a building, shall be in accordance with one of the following:

(1) The provisions of Section 510.0.

(2) Vents serving fan-assisted combustion system appliances, or combinations of fan-assisted combustion system and draft hood-equipped appliances, shall be sized in accordance with Section 510.0 or other engineering methods.

(3) For sizing an individual gas vent for a single, draft hood-equipped appliance, the effective area of the vent connector and the gas vent shall be not less than the area of the appliance draft hood outlet or greater than seven times the draft hood outlet area.

(4) For sizing a gas vent connected to two appliances with draft hoods, the effective area of the vent shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet or greater than seven times the smaller draft hood outlet area.

(5) Engineering methods. [NFPA 54:12.7.4.1] 509.6.2.2 Vent Offsets. Type B and Type L vents sized in accordance with Section 509.6.2.1(3) or Section 509.6.2.1(4) shall extend in a generally vertical direction with offsets not exceeding 45 degrees (0.79 rad), except that a vent system having not more than one 60 degree (1.05 rad) offset shall be permitted. Any angle greater than 45 degrees (0.79 rad) from the vertical is considered horizontal. The total horizontal distance of a vent plus the horizontal vent connector serving draft hood-equipped appliances shall not be greater than 75 percent of the vertical height of the vent. [NFPA 54:12.7.4.2] 509.6.2.3 Category II, Category III, and Cate- gory IV Appliances. The sizing of gas vents for Category II, Category III, and Category IV appliances shall be in accordance with the appliance manufacturers’ instructions. The sizing of plastic pipe specified by the appliance manufacturer as a venting material for Category II, III, and IV appliances shall be in accordance with the appliance manufacturers’ instructions.
CRC § 811.7 Medium relevance — show source text
811.7 Discharge . . . . . . . . . . . . . . . . . . .183

811.8 Diluted Chemicals . . . . . . . . . . . . .183

812.0 Clear Water Wastes . . . . . . . . . . .183

812.1 General . . . . . . . . . . . . . . . . . . . . .183

813.0 Swimming Pools . . . . . . . . . . . . . .183

813.1 General . . . . . . . . . . . . . . . . . . . . .183

814.0 Condensate Waste and Control . . .183

814.1 Condensate Disposal . . . . . . . . . .183

814.2 Condensate Control . . . . . . . . . . .184

814.3 Condensate Waste Pipe Material and Sizing . . . . . . . . . . . .184

Table 814.3 Minimum Condensate Pipe Size . . . . . . . . . . . . . . . . . . .184

814.4 Appliance Condensate Drains . . .184

814.5 Point of Discharge . . . . . . . . . . . .184

814.6 Condensate Waste from

Air-Conditioning Coils . . . . . . . . . .185

814.7 Plastic Fittings . . . . . . . . . . . . . . .185

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TABLE OF CONTENTS

CHAPTER 9 VENTS . . . . . . . . . . . . . . . . . . . . .187

901.0 General . . . . . . . . . . . . . . . . . . . . .189

901.1 Applicability . . . . . . . . . . . . . . . . . .189

901.2 Vents Required . . . . . . . . . . . . . . .189

901.3 Trap Seal Protection . . . . . . . . . . .189

902.0 Vents Not Required . . . . . . . . . . .189

902.1 Interceptor . . . . . . . . . . . . . . . . . .189

902.2 Bars, Soda Fountains, and Counter . . . . . . . . . . . . . . . . . . . . .189

903.0 Materials . . . . . . . . . . . . . . . . . . . .189

903.1 Applicable Standards . . . . . . . . . .189

903.2 Use of Copper or Copper Alloy Tubing . . . . . . . . . . . . . . . . .189

903.3 Changes in Direction . . . . . . . . . .189

904.0 Size of Vents . . . . . . . . . . . . . . . .189

904.1 Size . . . . . . . . . . . . . . . . . . . . . . . .189

904.2 Length . . . . . . . . . . . . . . . . . . . . . .189

CRC § 601.4.1 Medium relevance — show source text

Exception: Water closets shall be permitted to be up to 8 feet (2438 mm) horizontally from the stack where connected to the stack through a sanitary tee.

C 601.4.1 Other Fixtures. Fixtures other than water closets shall be not more than 12 feet (3658 mm) horizontally from the stack. C 601.4.2 Length of Vertical Piping. The length of vertical piping from a fixture trap to a horizontal branch shall not be considered in computing the fixture’s horizontal distance from the stack.

C 601.5 Maximum Vertical Drops from Fixtures. Vertical drops from fixture traps to horizontal branch piping shall be one size larger than the trap size, but not less than 2 inches (50 mm) in diameter. Vertical drops shall be 4 feet (1219 mm) maximum length. Fixture drains that are not increased in size, or have a vertical drop exceeding 4 feet (1219 mm) shall be individually vented. C 601.6 Additional Venting Required. Additional venting shall be provided where more than one water closet is on a horizontal branch and where the distance from a fixture trap to the stack exceeds the limits in Section C 601.4. Where additional venting is required, the fixture(s) shall be vented by one of the methods described in Section 908.0 through Section 911.5. The dry vent extensions for the additional venting shall connect to a branch vent, vent stack, stack vent, or be extended outdoors and terminate to the open air.

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APPENDIX C

TABLE C 601.2 SINGLE STACK SIZE*	Col2	Col3	Col4
MAXIMUM CONNECTED DRAINAGE FIXTURE UNITS	MAXIMUM CONNECTED DRAINAGE FIXTURE UNITS	MAXIMUM CONNECTED DRAINAGE FIXTURE UNITS	MAXIMUM CONNECTED DRAINAGE FIXTURE UNITS
STACK SIZE (inches)	STACKS LESS THAN 75 FEET IN HEIGHT	STACK 75 FEET TO LESS THAN 160 FEET IN HEIGHT	STACK 160 FEET OR GREATER IN HEIGHT
3	24	NP	NP
4	225	24	NP
5	480	225	24
6	1015	480	225
8	2320	1015	480
10	4500	2320	1015
12	8100	4500	2320
15	13 600	8100	4500

For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm

NP = Not permitted

C 601.7 Stack Offsets. Where there are no fixture drain connections below a horizontal offset in a stack, the offset does not need to be vented. Where there are fixture drain connections below a horizontal offset in a stack, the offset shall be vented. There shall be no fixture connections to a stack within 2 feet (610 mm) above and below a horizontal offset.

CRC § 510.1 Medium relevance — show source text
(1) Draft regulators and safety controls specifically listed for installation in venting systems and installed in accordance with the manufacturer’s installation instructions.

(2) Approved draft regulators and safety controls designed and installed in accordance with engineering methods.

(3) Listed heat reclaimers and automatically operated vent dampers installed in accordance with the manufacturers’ installation instructions.

(4) Vent dampers serving listed appliances installed in accordance with Section 510.1 or Section 510.2 or engineering methods.

(5) Approved economizers, heat reclaimers, and recuperators installed in venting systems of appliances not required to be equipped with draft hoods, provided the appliance manufacturer’s instructions cover the installation of such a device in the venting system and performance in accordance with Section 509.3 and Section 509.3.1 is obtained. [NFPA 54:12.16]

510.0 Sizing of Category I Venting Systems. 510.1 Additional Requirements to Single Appliance Vent. Venting Table 510.1.2(1) through Table 510.1.2(6) shall not be used where obstructions are installed in the venting system. The installation of vents serving listed appliances with vent dampers shall be in accordance with the appliance manufacturer’s instructions or in accordance with the following:

»

B gas vents that pass through walls or partitions constructed of combustible material shall be installed

with not less than the listed clearance to combustible

material.

(2) Vent connectors shall be permitted to pass through ceilings, floors, or walls in accordance with Section 509.7.3.1 and Section 509.7.3.5.

509.10.13.1 Medium-Heat Appliances. Vent connectors for medium-heat appliances shall not pass through walls or partitions constructed of combustible material. [NFPA 54:12.11.14.2] 509.11 Vent Connectors for Category II, Category III, and Category IV Appliances. The vent connectors for Category II, Category III, and Category IV appliances shall be in accordance with Section 509.4 through Section 509.4.3.

[NFPA 54:12.12]

509.12 Appliances Requiring Draft Hoods. Vented appliances shall be installed with draft hoods.

Exception: Dual oven-type combination ranges; direct vent appliances; fan-assisted combustion system appliances; appliances requiring chimney draft for operation; single-firebox boilers equipped with conversion burners with inputs greater than 400 000 Btu/h (117 kW); appliances equipped with blast, power, or pressure burners that are not listed for use with draft hoods; and appliances designed for forced venting. [NFPA 54:12.13.1]

509.12.1 Installation. A draft hood supplied with or forming a part of a listed vented appliance shall be installed without alteration, exactly as furnished and specified by the appliance manufacturer. [NFPA 54:12.13.2]

If a draft hood is not supplied by the appliance manufacturer where one is required, a draft hood shall be installed, be of a listed or approved type, and, in the absence of other instructions, be of the same size as the appliance flue collar. Where a draft hood is required with a conversion burner, it shall be of a listed or approved type. [NFPA 54:12.13.2.1]
CRC § 601.2.1 Medium relevance — show source text
Not more than two water closets shall be permitted to discharge to a 3 inch (80 mm) stack. Stacks shall be uniformly sized based on the total connected drainage fixture unit load, with no reductions in size. C 601.2.1 Stack Vent. The drainage stack vent shall have a stack vent of the same size terminating to the outdoors. C 601.3 Branch Size. Horizontal branches connecting to a single-stack vent system shall be sized in accordance with Table 703.2.

Exceptions:

(1) Not more than one water closet within 18 inches (457 mm) of the stack horizontally shall be permitted on a 3 inch (80 mm) horizontal branch.

(2) A water closet within 18 inches (457 mm) of a stack horizontally and one other fixture with up to 1 [1] ⁄ 2 inch (40 mm) fixture drain size shall be permitted on a 3 inch (80 mm) horizontal branch where connected to the stack through a sanitary tee. C 601.4 Length of Horizontal Branches. Water closets shall be not more than 4 feet (1219 mm) horizontally from the stack.

Exception: Water closets shall be permitted to be up to 8 feet (2438 mm) horizontally from the stack where connected to the stack through a sanitary tee.

C 601.4.1 Other Fixtures. Fixtures other than water closets shall be not more than 12 feet (3658 mm) horizontally from the stack. C 601.4.2 Length of Vertical Piping. The length of vertical piping from a fixture trap to a horizontal branch shall not be considered in computing the fixture’s horizontal distance from the stack.

C 601.5 Maximum Vertical Drops from Fixtures. Vertical drops from fixture traps to horizontal branch piping shall be one size larger than the trap size, but not less than 2 inches (50 mm) in diameter. Vertical drops shall be 4 feet (1219 mm) maximum length. Fixture drains that are not increased in size, or have a vertical drop exceeding 4 feet (1219 mm) shall be individually vented. C 601.6 Additional Venting Required. Additional venting shall be provided where more than one water closet is on a horizontal branch and where the distance from a fixture trap to the stack exceeds the limits in Section C 601.4. Where additional venting is required, the fixture(s) shall be vented by one of the methods described in Section 908.0 through Section 911.5. The dry vent extensions for the additional venting shall connect to a branch vent, vent stack, stack vent, or be extended outdoors and terminate to the open air.

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APPENDIX C
CRC § 811.0. Medium relevance — show source text
defined in Section 811.0.

903.2.3 Marking. Copper or copper alloy tubing, in addition to the required incised marking, shall be marked in accordance with either ASTM B306 or ASTM B88. The colors shall be Type K, green; Type L, blue; Type M, red; and Type DWV, yellow. 903.3 Changes in Direction. Changes in the direction of vent piping shall be made by the appropriate use of approved fittings, and no such pipe shall be strained or bent. Burred ends shall be reamed to the full bore of the pipe.

904.0 Size of Vents.

904.1 Size. The size of vent piping shall be determined from its length and the total number of fixture units connected thereto, in accordance with Table 703.2. The diameter of an individual vent shall be not less than 1 [1] ⁄ 4 inches (32 mm) nor less than one-half the diameter of the drain to which it is connected. In addition, the drainage piping of each building and each connection to a public sewer or a private sewage disposal system shall be vented by means of one or more vent pipes, the aggregate cross-sectional area of which shall be not less than that of the largest required building sewer as determined from Table 703.2. Vent pipes from fixtures located upstream from pumps, ejectors, backwater valves, or other devices that obstruct the free flow of air and other gases between the building sewer and the outside atmosphere shall not be used for meeting the cross-sectional area venting requirements of this section. Exception: Where connected to a common building sewer, the drainage piping of two or more buildings located on the same lot and under one ownership shall be permitted to be vented by means of piping sized in accordance with Table 703.2, provided the aggregate cross-sectional area of vents is not less than that of the largest required common building sewer. 904.2 Length. Not more than one-third of the total permitted length, in accordance with Table 703.2, of a minimumsized vent shall be installed in a horizontal position. Where a minimum-sized vent is increased one pipe size for its entire length, the maximum length limitation shall not apply.

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VENTS

905.0 Vent Pipe Grades and Connections. 905.1 Grade. Vent and branch vent pipes shall be free from drops or sags, and each such vent shall be level or shall be so graded and connected as to drip back by gravity to the drainage pipe it serves. 905.2 Horizontal Drainage Pipe. Where vents connect to a horizontal drainage pipe, each vent pipe shall have its invert taken off above the drainage centerline of such pipe downstream of the trap being served. 905.3 Vent Pipe Rise. Unless prohibited by structural conditions, each vent shall rise vertically to a point not less than 6 inches (152 mm) above the flood-level rim of the fixture served before offsetting horizontally, and where two or more vent pipes converge, each such vent pipe shall rise to a point not less than 6 inches (152 mm) in height above the floodlevel rim of the plumbing fixture it serves before being connected to any other vent. Vents less than 6 inches (152 mm) above the flood-level rim of the fixture shall be installed with approved drainage fittings, material, and grade to the drain.

CRC § 301.3. Medium relevance — show source text

form plumbing design work. Details are necessary to ensure compliance with the requirements of this section, together with a full description of the complete installation including quality, grade of materials, equipment, construction, and methods of assembly and installation. Components, materials, and equipment shall comply with standards and specifications listed in Chapter 17 of this code or approved by the Authority Having Jurisdiction and other national consensus standards applicable to plumbing systems and materials. Where such standards and specifications are not available, alternate materials and equipment shall be approved in accordance with Section 301.3.

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APPENDIX C

Col1	Col2	TABLE C 401.1 SIZE AND LENGTH OF VENTS	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Col11
SIZE OF SOIL OR WASTE STACK (inches)	FIXTURE UNITS CONNECTED	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)	DIAMETER OF VENT REQUIRED (inches)
SIZE OF SOIL OR WASTE STACK (inches)	FIXTURE UNITS CONNECTED	11⁄4	11⁄2	2	21⁄2	3	4	5	6	8
SIZE OF SOIL OR WASTE STACK (inches)	FIXTURE UNITS CONNECTED	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)	MAXIMUM LENGTH OF VENT (feet)
11⁄2	8	50	150	––	––	––	––	––	––	––
2	12	30	75	200	––	––	––	––	––	––
2	20	26	50	150	––	––	––	––	––	––
21⁄2	42	––	30	1

CRC § 505.0 Medium relevance — show source text
Oil-burning and other . . . . . . . . . . . . . . . . . . . . . .505.0 Permits required . . . . . . . . . . . . . . . . . . . . . . . . . .502.0

Pressure-relief valves . . . . . . . . . . .504.4, 504.6, 505.2,

608.2 – 608.5

Protection . . . . . . . . . . . . . . . . . . .504.3 – 504.6, 505.2,

507.2, 507.8, 507.10,

507.14.1, 507.24

Relief valve discharge . . . . . . . . . . . . . . . . . . . . . .608.5 Seismic provisions . . . . . . . . . . . . . . . . . . . . . . . . .507.2 Temperature and pressure-relief valves . . . . . . . . . . . . . . .504.6, 505.2 Temperature-limiting devices . . . . . . . . . . . . . . . . .504.5

Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . .509.0, 510.0

Water heating system requirements . . . . . . . . . . . .501.2 WATER SOFTENERS . . . . . . . . . . . . . . . . 611.4, Table 611.4

WATER STATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225.0

WATER TESTS

Building sewers . . . . . . . . . . . . . . . . . . . . . . . . . . .723.0 Drainage and vent systems . . . . . . . . . . . . .105.3, 712.2 Storm drainage . . . . . . . . . . . . . . . . . .1107.2.1, 1107.2.3 Water supply systems . . . . . . . .105.2.1.1, 105.3, 609.4

WATERPROOFING

AND WATERTIGHT

Building sewer . . . . . . . . . . . . . . . . . . . . . . . . . . . .723.1

Cleanouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .707.3

Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105.3

Drain pans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .507.5

Fixtures . . . . . . . . . . . . . . . . .402.2, 408.6, 408.8, 418.2
CPC § 2025 Medium relevance — show source text
Gas Piping| |13|Health Care Facilities and Medical Gas and Medical Vacuum Systems| |14|Firestop Protection| |15|Alternate Water Sources for Nonpotable Applications| |16|Nonpotable Rainwater Catchment Systems| |17|Referenced Standards| |Appendix A|Recommended Rules for Sizing the Water Supply System| |Appendix B|Explanatory Notes on Combination Waste and Vent Systems| |Appendix C|Alternate Plumbing Systems| |Appendix D|Sizing Storm Water Drainage Systems| |Appendix E|Manufactured/Mobile Home Parks and Recreational Vehicle Parks| |Appendix F|Firefighter Breathing Air Replenishment Systems| |Appendix G|Sizing of Venting Systems| |Appendix H|Private Sewage Disposal Systems| |Appendix I|Installation Standards| |Appendix J|Combination of Indoor and Outdoor Combustion and Ventilation Opening Design| |Appendix K|Potable Rainwater Catchment Systems| |Appendix L|Sustainable Practices| |Appendix M|Peak Water Demand Calculator| |Appendix N|Impact of Water Temperature on the Potential for Scalding and Legionella Growth| |Appendix O|Non-Sewered Sanitation Systems| |Appendix P|Professional Qualifications| |Appendix Q|Indoor Horticultural Facilities| |Appendix R|Tiny Houses| |Appendix S|Onsite Stormwater Treatment Systems|

2025 CALIFORNIA PLUMBING CODE xiii

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FORMAT OF THE UNIFORM PLUMBING CODE

The following is a summary of the scope and intent of the provisions addressed within the chapters and appendices of the Uniform Plumbing Code :

Chapter 1 Administration.

Chapter 1 regulates the application, enforcement, and administration of subsequent requirements of the code. As well as establishing the scope of the code, this chapter is concerned with enforcing the requirements contained in the body of the code. A plumbing code, as with any other code, is intended to be adopted as a legally enforceable document to safeguard health, safety, property, and public welfare. The code cannot be effective without satisfactory provisions for its administration and enforcement. The Authority Having Jurisdiction is to review the proposed and completed work and to decide whether a plumbing system conforms to the code requirements. As a public servant, the Authority Having Jurisdiction enforces the code in an unbiased, proper manner. The design professional is responsible for the design of a safe plumbing system. The contractor is responsible for installing the system in accordance with the plans.

Chapter 2 Definitions.

To maintain consistency and encourage the use of common terminology, Chapter 2 establishes definitions to provide clarity of terms and promote the use of a common language throughout the code. Understanding definitions within the context of their application enables greater collaboration, efficiency, standardization, and interpretation in applying and enforcing terms used throughout the code. Codes are technical documents, and every term can impact the meaning of the code text. Terms not defined have a normally accepted meaning.

Chapter 3 General Regulations.

Chapter 3 regulates the general requirements, not specific to other chapters, for installing plumbing systems. Many regulations are not specific plumbing requirements but relate to the overall plumbing system. This chapter contains safety requirements for installing plumbing and also contains nonplumbing requirements for identifying pipes, pipe fittings, traps, fixtures, materials, and devices used in plumbing systems.
CRC § 11.0 Medium relevance — show source text
11.0 - 1.11.11_|||X|||||||||||||||||||||| |1.13.0||||||||||||||||||||X||||| |Division II - Scope and
Administration||||||||||||||||||||||||| |101.0||||||||||X|X|X||X|X|||||||||| |102.0||||||||||X|X|X||X|X|||||||||| |103.0||||||||||X|X|X||X|X|||||||||| |104.2 Items 1 & 2||||X|X|||||||||||||||||||| |104.3.1||||||||||X|X|X||X|X|||||||||| |104.4.3.1|X|||||||||||||||||||||||| |105.0||||||||||X|X|X||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.

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CHAPTER 1

ADMINISTRATION

DIVISION I

CALIFORNIA ADMINISTRATION

1.1.0 General.

1.1.1 Title. These regulations shall be known as the Califor- nia Plumbing Code, may be cited as such and will be referred to herein as “this code.” The California Plumbing Code is Part 5 of thirteen parts of the official compilation and publi- cation of the adoption, amendment, and repeal of plumbing regulations to the California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This part incorporates by adoption the 2024 Uniform Plumb- ing Code of the International Association of Plumbing and Mechanical Officials with necessary California amendments.

1.1.2 Purpose. The purpose of this code is to establish the minimum requirements to safeguard the public health, safety and general welfare through structural strength, means of egress facilities, stability, access to persons with disabilities, sanitation, adequate lighting and ventilation, and energy con- servation; safety to life and property from fire and other haz- ards attributed to the built environment; and to provide safety to fire fighters and emergency responders during emergency operations.

1.1.3 Scope. The provisions of this code shall apply to the construction, alteration, movement, enlargement, replace- ment, repair, equipment, use and occupancy, location, main- tenance, removal, and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures throughout the State of California.
CRC § 1323.13.3 Medium relevance — show source text
2, 1323.13.3| |1326.4 - 1326.10|1326.5 - 1326.11| |1505.6 - 1505.14|1505.5 - 1505.13| |Figure 1505.10|Figure 1505.9| |1506.6 - 1506.13|1506.5 - 1506.12| |1603.3 - 1603.4|1603.4 - 1603.5| |Table 1603.4|Table 1603.5| |1603.5 - 1603.19|1603.6 - 1603.20| |1603.20|1503.2.4| |L 402.9 - L 402.11|L 402.8 - L 402.10| |L 404.9 - L 404.12|L 404.8 - L 404.11| |L 411.5, L 411.6|L 411.2, L411.3| |L 411.7|L 411.4| |L 411.9 - L 411.12|L 411.5 - L 411.8|

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RELATED PUBLICATIONS AND SERVICES

The Documents Listed are Not by this Reference Adopted by The State of California.

IAPMO provides a variety of other products which are useful for inspectors, building officials, architects, engineers,

manufacturers, contractors, plumbers, and apprentices.

IAPMO Headquarters Directory

4755 East Philadelphia Street, Ontario, California 91761-2816

Publication Order Desk Phone: 800-85-IAPMO

Publication Toll Free Fax: 877-85-CODES

E-mail: iapmo@iapmo.org

Website: www.iapmo.org

Free Code Question: 800-201-0335

Uniform Plumbing Code – 2024 Edition:

The Uniform Plumbing Code is the most widely adopted plumbing code in the world. The 2024 edition contains complete “turnkey” requirements for the installation and maintenance of plumbing systems, all in one easy to use book.

Uniform Plumbing Code Illustrated Training Manual:

The UPC Illustrated Training Manual is an excellent reference for anyone involved in the plumbing industry. It contains an extensive definitions section and several hundred comprehensive technical diagrams and illustrations. It serves as a textbook, and it also is useful as a valuable tool for explaining the intent and use of the Code.

Uniform Plumbing Code Study Guide:

This book is the perfect complement to the UPC Illustrated Training Manual. Alone, it constitutes a complete self-study course for learning the UPC. It has hundreds of questions, general practice exams, and plumbing math, pipe sizing exercises and fitting identification. A big help in getting you ready for a certification exam!

Guide to Important Code Questions to the Uniform Plumbing Code:

An excellent reference for learning and understanding plumbing code changes and identifies code changes between editions. It is a useful tool for preparing code change proposals.

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:

Contains technical diagrams and illustrations that demonstrate the intent and use of the UMC. A great reference for everyone involved in Mechanical HVACR design and installation.

Uniform Mechanical Code Study Guide:
CRC § 4.1 Medium relevance — show source text
- 100°F
  (16°C-38°C)|1 h|6 h|2 h|12 h|6 h|24 h| |40°F-60°F
  (4°C-16°C)|2 h|12 h|4 h|24 h|12 h|48 h| |10°F- 40°F
  (-12°C+4°C)|8 h|48 h|16 h|96 h|48 h|8 days| |*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|*If gaps or loose fits are encountered in the system, double these cure times.|
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IS 33

FIGURE 1

LOCATION OF THRUST BLOCKS (STANDARD AND METRIC COMBINED) A COMPARISON OF THRUST-BLOCK AREAS (See Section 4.1)

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IS 33

FIGURE 2

THRUST BLOCK BEARING AREA (See Section 5.2.2)

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IS 33

Uniform Plumbing Code References for Ductile Iron and PVC Pressure Building Supply and Exterior Cold-Water Piping

The following sections of the 2024 Uniform Plumbing Code apply to ductile iron and PVC pressure building supply and exterior cold-water piping.

Chapter 3 General Regulations

309.0 Workmanship

312.0 Protection of Piping, Materials, and Struc tures

313.0 Hangers, Supports, and Anchors

314.0 Trenching, Excavation, and Backfill

Chapter 6 Water Supply and Distribution

604.0 Materials (water piping)

Table 604.1 Materials for Building Supply and Water Distribution Piping and Fittings

605.4 Ductile Iron Pipe and Joints

605.12 PVC Plastic Pipe and Joints

605.16.2 Plastic Pipe to Other Materials

609.0 Installation, Testing, Unions, and Location

Abbreviations

IAPMO International Association of Plumbing and Mechanical Officials

UPC Uniform Plumbing Code published by IAPMO

AWWA American Water Works Association

CSA Canadian Standards Association

Applicable Standards.

ASME B16.4 Gray Iron Threaded Fittings Classes 125 and 250

ASTM D1785 Poly (Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120

ASTM D2241 Poly (Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR Series)

CRC § 2.6.2 Medium relevance — show source text

Adopting Agency	BSC	BSC- CG	SFM	Col5	HCD	Col7	Col8	DSA	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
Adopting Agency	BSC	BSC- CG	T-24	T-19*	1	2	1/AC	AC	SS	1	1R	2	3	4	5	5	5	5	5	5	5	5	5
Adopt Entire Chapter
Adopt Entire Chapter as amended (amended sections listed below)			X
Adopt only those sections that are listed below
[California Code of Regulations, Title 19, Division 1]				X
Chapter / Section
903.2.6.2			X
903.2.7			X
903.2.8			X
903.2.8.2			X
903.2.8.3			X
903.2.8.4			X
903.2.10.2			X
Table 903.2.11.6			X
903.2.13 – 903.2.21			X
903.3.1.1			X
903.3.1.1.1			X
903.3.1.2			X
903.3.1.2.3			X
903.3.1.1.4			X
903.3.1.3			X
903.3.2			X
903.3.5			X
903.3.9			X
903.3.10			X
[T-19 §904 (a)(2)]				X
[T-19 §904 (c)]				X
[T-19 §904.7 (a-c)]				X
904.1.1			†
904.5			X
904.6			X
904.7			X
904.7.

CRC § 0.60 Medium relevance — show source text
60**|** 0.60**| ||PIPE SIZE (inch)|PIPE SIZE (inch)|PIPE SIZE (inch)|PIPE SIZE (inch)|PIPE SIZE (inch)|PIPE SIZE (inch)|PIPE SIZE (inch)|PIPE SIZE (inch)| |NOMINAL OD:|1⁄2|3⁄4|1|1 1⁄4|1 1⁄2|2|3|4| |DESIGNATION:|SDR 9.3|SDR 11|SDR 11|SDR 10|SDR 11|SDR 11|SDR 11|SDR 11| |ACTUAL ID:|0.660|0.860|1.077|1.328|1.554|1.943|2.864|3.682| |LENGTH (feet)|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR|CAPACITY IN CUBIC FEET OF GAS PER HOUR| |10|153|305|551|955|1440|2590|7170|13 900| |20|105|210|379|656|991|1780|4920|9520| |30|84|169|304|527|796|1430|3950|7640| |40|72|144|260|451|681|1220|3380|6540| |50|64|128|231|400|604|1080|3000|5800| |60|58|116|209|362|547|983|2720|5250| |70|53|107|192|333|503|904|2500|4830| |80|50|99|179|310|468|841|2330|4500| |90|46|93|168|291|439|789|2180|4220| |100|44|88|159|275|415|745|2060|3990| |125|39|78|141|243|368|661|1830|3530| |150|35|71|127|221|333|598|1660|3200| |175|32|65|117|203|306|551|1520|2940| |200|30|60|109|189|285|512|1420|2740| |250|27|54|97|167|253|454|1260|2430| |300|24|48|88|152|229|411|1140|2200| |350|22|45|81|139|211|378|1050|2020| |400|21|42|75|130|196|352|974|1880| |450|19|39|70|122|184|330|914|1770| |500|18|37|66|115|174|312|863|1670|
CRC § 312.0 Medium relevance — show source text
312.0 Protection of Piping, Materials, and Structures

314.0 Trenching, Excavation, and Backfill

701.3 Drainage Fittings

705.5.1.1 Butt Fusion Joints

705.5.1.2 Electro-Fusion Joints

705.5.1.3 Socket-Fusion Joints

723.0 Building Sewer Test

TABLE 1

CLEANOUTS (See Section 4.6.1)

The following standards from Tables 1701.1 and 1701.2 of the 2024 Uniform Plumbing Code apply.

Table 1701.1 Standards

ASTM D2239 Polyethylene (PE) Plastic Pipe (SIDRPR) Based on Controlled Inside Diameter

ASTM D2683 Socket-Type Polyethylene Fittings for Outside Diameter-Controlled Polyethylene Pipe and Tubing

ASTM D3261 Butt Heat Fusion Polyethylene (PE) Plastic Fittings for Polyethylene (PE) Plastic Pipe and Tubing

ASTM F714 Polyethylene (PE) Plastic Pipe (DRPR) Based on Outside Diameter

ASTM F894 Polyethylene (PE) Large Diameter Profile Wall Sewer and Drain Pipe

ASTM F1055 Electrofusion Type Polyethylene Fittings for Outside Diameter Controlled Polyethylene and Crosslinked Polyethylene (PEX) Pipe and Tubing

ASTM F2620 Heat Fusion Joining of Polyethylene Pipe and Fittings

Table 1701.2 Standards

ASTM D2657 Heat Fusion Joining of Polyolefin Pipe and Fittings

IAPMO PS 25 Metallic Fittings for Joining Polyethylene Pipe for Water Service and Yard Piping

Note: For SI units: 1 inch = 25 mm

2025 CALIFORNIA PLUMBING CODE 453

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

454 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

"The information contained in this appendix is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this appendix may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the standard."

The following IAPMO Installation Standard is included here for the convenience of the users of the Uniform Plumbing Code. It is not considered as a part of the Uniform Plumbing Code unless formally adopted as such. This Installation Standard is an independent, stand-alone document published by the International Association of Plumbing and Mechanical Officials and is printed herein by the expressed written permission of IAPMO.

INSTALLATION STANDARD FOR PEX TUBING SYSTEMS

FOR HOT- AND COLD-WATER DISTRIBUTION

IAPMO IS 31-2022

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

1 Scope

1.1 General

1.1.1 This Standard specifies requirements for the installation of SDR 9 CTS crosslinked polyethylene (PEX) tubing and fittings, including cold-expansion, crimp, press, and mechanical compression fittings, intended for hot- and cold-water distribution systems within buildings.

1.1.2 This Standards applies to
CRC § 310.13 Medium relevance — show source text
ante rooms.

310.13 [SFM] For applications listed in Section 1.11.0 regu- lated by the Office of the State Fire Marshal, plastic piping shall not be exposed as a portion of the interior room finish in a build- ing or structure if the piping has a flame-spread rating exceed- ing 75 when tested in accordance with ASTM E84, “Test for Surface Burning Characteristics of Building Materials.” 310.14 Services/Systems and Utilities. [OSHPD 1, 2, 4 & 5] Refer to Sections 1224.4.1, 1225.2.1 and 1228.4.1.1, Cal- ifornia Building Code. 310.15 Telephone and Data Equipment Rooms.

[OSHPD 1, 4 & 5] Where telecommunications service entrance rooms, technology equipment centers, or technology distribution rooms are provided in accordance with Section 1224.5 of the California Building Code, plumbing equipment and fixtures that are not directly related to the support of the room shall not be installed in or pass through the room.

311.0 Independent Systems. 311.1 General. The drainage system of each new building and new work installed in an existing building shall be separate and independent from that of any other building, and, where available, every building shall have an independent connection with a public or private sewer.

Exception: Where one building stands in the rear of another building on an interior lot, and no public or private sewer is available or can be constructed to the rear building through an adjoining court, yard, or driveway, the building drain from the front building shall be permitted to be extended to the rear building.

Note: Accessory dwelling units are not required to have inde- pendent service utility (drainage) connections provided they meet the specific requirements in Government Code Section 65852.2.

312.0 Protection of Piping, Tubing, Materials, and Structures.

312.1 General. Piping passing under or through walls shall be protected from breakage. Piping passing through or under cinders or other corrosive materials shall be protected from external corrosion in an approved manner. Approved provisions shall be made for expansion of hot water piping. Voids around piping passing through concrete floors on the ground shall be sealed.

312.2 Installation. Piping in connection with a plumbing system shall be so installed that piping or connections will not be subject to undue strains or stresses, and provisions shall be made for expansion, contraction, and structural settlement. No plumbing piping shall be directly embedded in concrete or masonry. No structural member shall be seriously weakened or impaired by cutting, notching, or otherwise, as defined in the California Building Code or California Residential Code . 312.3 Building Sewer and Drainage Piping. No building sewer or other drainage piping or part thereof, constructed of materials other than those approved for use under or within a building, shall be installed under or within 2 feet (610 mm) of a building or structure, or less than 1 foot (305 mm) below the surface of the ground. 312.4 Corrosion, Erosion, and Mechanical Damage. Piping subject to corrosion, erosion, or mechanical damage shall be protected in an approved manner. **312.5 Protectively Coated Pipe.
CRC § 8.2 Medium relevance — show source text
8.2|||X||||||||||||||||||||| |903.2.8.3|||X||||||||||||||||||||| |903.2.8.4|||X||||||||||||||||||||| |903.2.10.2|||X||||||||||||||||||||| |Table 903.2.11.6|||X||||||||||||||||||||| |903.2.13 – 903.2.21|||X||||||||||||||||||||| |903.3.1.1|||X||||||||||||||||||||| |903.3.1.1.1|||X||||||||||||||||||||| |903.3.1.2|||X||||||||||||||||||||| |903.3.1.2.3|||X||||||||||||||||||||| |903.3.1.1.4|||X||||||||||||||||||||| |903.3.1.3|||X||||||||||||||||||||| |903.3.2|||X||||||||||||||||||||| |903.3.5|||X||||||||||||||||||||| |903.3.9|||X||||||||||||||||||||| |903.3.10|||X||||||||||||||||||||| |[T-19 §904 (a)(2)]||||X|||||||||||||||||||| |[T-19 §904 (c)]||||X|||||||||||||||||||| |[T-19 §904.7 (a-c)]||||X|||||||||||||||||||| |904.1.1|||†||||||||||||||||||||| |904.5|||X||||||||||||||||||||| |904.6|||X||||||||||||||||||||| |904.7|||X||||||||||||||||||||| |904.7.1|||X||||||||||||||||||||| |904.8|||X||||||||||||||||||||| |904.8.1|||X||||||||||||||||||||| |904.9|||X||||||||||||||||||||| |904.9.1|||X||||||||||||||||||||| |904.10|||X||||||||||||||||||||| |904.10.1|||X||||||||||||||||||||| |904.11.3|||X||||||||||||||||||||| |904.14|||X||||||||||||||||||||| |904.14.5|||X||||||||||||||||||||| |904.15|||X||||||||||||||||||||| |905.1|||X||||||||||||||||||||| |905.2|||X||||||||||||||||||||| |905.3|||X||||||||||||||||||||| |905.3.1|||X||||||||||||||||||||| |905.3.8|||X||||||||||||||||||||| |905.3.8.1|||X||||||||||||||||||||| |905.3.8.2|||X|||||||||||||||||||||

9-2 2025 CALIFORNIA FIRE CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

CHAPTER 9 – FIRE PROTECTION AND LIFE SAFETY SYSTEMS—continued

Frequently asked questions

Do I always have to upsizing a vent if I run it horizontally?

Not always. Horizontal runs on a minimum‑sized vent are limited to one‑third of the vent’s permitted length from the sizing table. If you exceed that, either upsized the vent one full pipe size for its entire length or reroute vertically — § 904.2.

What is the smallest vent I can use for a single sink?

An individual vent must be at least 1 1/4 inches and not less than one‑half the diameter of the drain it serves; however, final selection must be verified against the sizing table (Table 703.2) and length — § 904.1.

How close to the trap flood rim must a vent rise before I offset it?

Each vent (or branch vent) must rise at least 6 inches (152 mm) above the fixture flood‑level rim before any horizontal offset or connection to another vent — § 905.3.

Are the vent material standards different from drain materials?

Vent materials and fittings must meet the applicable referenced standards (see the code Table references); follow § 903.1 for the materials requirements and the code’s referenced standards tables.

Can a vent be used to meet the sewer cross‑sectional-area vent requirement if it’s upstream of a pump or backwater valve?

No — vents from fixtures located upstream of pumps, ejectors, backwater valves, or other devices that block free air/gas flow between the building sewer and outside atmosphere shall not be used toward the building‑sewer cross‑sectional area venting requirement — § 904.1.

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