CPC · California Plumbing Code
Workmanship, Hangers & Protection
This hub orients you to the CPC provisions on workmanship, protection of piping, and hangers/supports (primarily §§309, 312 and 313) and why they matter.
Last reviewed: July 6, 2026
Overview
This area of the California Plumbing Code (CPC) covers the workmanship and installation standards that keep plumbing systems durable, safe, and serviceable — from basic craft standards to protection against corrosion, freezing, mechanical damage, and fire‑rating at penetrations. The CPC organizes these rules in Chapter 3 general regulations, including §309.0 (Workmanship) and §312.0 (Protection of Piping, Tubing, Materials, and Structures) as the primary provisions that describe required installation practices and protective measures.
Hangers, supports and anchors are handled together under §313.0 (Hangers, Supports, and Anchors), which specifies acceptable hanger materials, spacing, hanger‑rod sizes and requirements to prevent undue strain, vibration, or corrosion; the code also references standards such as MSS SP‑58 for pipe hanger manufacture and installation. Key details (for example, hanger rod sizes and suspended‑piping spacing) and related gas‑piping support rules are set out in these sections and their tables.
Good workmanship and correct protection matter because they reduce leaks and pipe failures, prevent structural damage or premature corrosion, maintain fire‑resistance and freezing protection at penetrations, and simplify inspection and testing. The CPC ties these provisions to inspection and testing requirements and cross‑references building and fire‑code requirements (for fire‑resistant construction, sleeves, nail plates, etc.), so compliance is essential for plan approval and final inspection.
In this section
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 506.8.1 High relevance — show source text
506.8.1 Loads. Duct supports shall be designed to carry the weight of the duct half filled with material. Where sprinkler protection is provided or cleaning of the duct will be performed, the hanger’s design shall include the weight of any expected liquid accumulation. Duct supports shall be designed to prevent placing loads on connected equipment. [NFPA 91:4.6.1 – 4.6.3]
506.8.2 Corrosion. Hangers and supports exposed to corrosive atmospheres shall be resistant to the corrosive atmospheres. [NFPA 91:4.6.4]
506.8.3 Vibration and Stress. To avoid vibration and stress on the duct, hangers and supports shall be securely fastened to the building or structure. [NFPA 91:4.6.5]
506.8.4 Expansion and Contraction. Hangers and supports shall be designed to allow for expansion and contraction. [NFPA 91:4.6.6]
506.9 Protection from Physical Damage. Ducts and exhaust equipment installed in locations where they are subject to physical damage shall be protected by guards.
506.10 Duct Clearances. Unless the conditions stipulated in Section 506.10.1 or Section 506.10.2 exist, all duct systems and system components shall have a clearance of at least 6 inches (152 mm) from stored combustible materials, and not less than [1] ⁄ 2 of an inch (13 mm) clearance from combustible construction. [NFPA 91:4.7.1]
506.10.1 Protection Provided. Where stored combustible material or combustible construction is protected from ductwork by the use of materials or products listed for protection purposes, clearance shall be maintained in accordance with those listings. [NFPA 91:4.7.1.1]
506.10.2 Systems Conveying Combustible Mate- rials. Unless the conditions stipulated in Section 506.10.3 exist, all duct systems and system components handling combustible materials shall have a clearance of not less than 18 inches (457 mm) from stored combustible materials or combustible construction. [NFPA 91:4.7.2]
506.10.3 Reduced Clearance Permitted. When the ductwork system is operating at 140°F (60°C) or below and is equipped with an approved automatic extinguishing system designed for the specific hazard, the clearance shall be permitted to be reduced to 6 inches (152 mm) from combustible materials and [1] ⁄ 2 of an inch (12.7 mm) from combustible construction. [NFPA 91:4.7.2.1]
506.10.4 Clearance Increases. All duct systems and system components operating at temperatures above 140°F (60°C) shall have clearances from stored combustible materials or combustible construction not less
than those listed in Table 506.10.4. [NFPA 91:4.7.3]
TABLE 506.10.4
BASIC MINIMUM CLEARANCES TO UNPROTECTED SURFACES
[NFPA 91: TABLE 4.7.3]
CPC § 309.0 Medium relevance — show source text
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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)
ASTM D2466 Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40
ASTM D2467 Poly (Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80
ASTM F1970 Special Engineered Fittings, Appurtenances or Valves for use in Poly (Vinyl Chloride) (PVC) or Chlorinated Poly (Vinyl Chloride) (CPVC) Systems
AWWA C110 Ductile Iron and Gray-Iron Fittings
AWWA C111 Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings
AWWA C151 Ductile-Iron Pipe, Centrifugally Cast
AWWA C153 Ductile-Iron Compact Fitting
AWWA C900 Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 in. through 12 in. (100 mm through 300 mm)
AWWA C904 Crosslinked Polyethylene (PEX) Pressure Tubing, ½ in. through 3 In. (13 mm through 76 mm), for Water Service
AWWA C907 Injection-Molded Polyvinyl Chloride (PVC) Pressure Fittings, 4 In, through 12 in (100 mm through 300 mm) for Water, Wastewater and Reclaimed Water Service
IAPMO/
ANSI UPC-1 Uniform Plumbing Code
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CPC § 312.0 Medium relevance — show source text
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. Protectively coated pipe or tubing shall be inspected and tested, and a visible void, damage, or imperfection to the pipe coating shall be repaired in an approved manner. 312.6 Freezing Protection. No water, soil, or waste pipe shall be installed or permitted outside of a building, in attics or crawl spaces, or in an exterior wall unless, where necessary, adequate provision is made to protect such pipe from freezing. 312.7 Fire-Resistant Construction. Piping penetrations of fire-resistance-rated walls, partitions, floors, floor/ceiling assemblies, roof/ceiling assemblies, or shaft enclosures shall be protected in accordance with the requirements of the Cal- ifornia Building Code or California Residential Code . 312.8 Waterproofing of Openings. Joints at the roof around pipes, ducts, or other appurtenances shall be made watertight by the use of lead, copper, galvanized iron, or other approved flashings or flashing material. Exterior wall openings shall be made watertight. Counterflashing shall not restrict the required internal cross-sectional area of the vent. 312.9 Steel Nail Plates. Plastic piping or tubing, and copper or copper alloy piping or tubing penetrating framing members to within 1 inch (25.4 mm) of the exposed framing shall be protected by steel nail plates not less than No. 18 gauge (0.0478 inches) (1.2 mm) in thickness. The steel nail plate shall extend along the framing member not less than 1 [1] ⁄ 2 inches (38 mm) beyond the outside diameter of the pipe or tubing. Fuel gas piping shall be protected in accordance with Section 1210.4.3.
CPC § 6.8947 Medium relevance — show source text
For SI units: 1 pound-force per square inch = 6.8947 kPa, 1 inch of mercury = 3.386 kPa
1323.1.6 Engineering Methods. For conditions other than those covered by Section 1323.1.4, such as longer runs of greater gas or vacuum demands, the size of each medical gas or vacuum piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each system shall be so designed that the total pressure drop or gain between the source equipment and an outlet or inlet shall not exceed the allowable pressures shown in Table 1305.1. 1323.2 Pipe Protection. Piping shall be protected against freezing, corrosion, and physical damage. [NFPA 99:5.1.10.11.2] 1323.2.1 Exposed Piping. Piping exposed in corridors and other areas where subject to physical damage from the movement of carts, stretchers, portable equipment, or vehicles shall be protected. [NFPA 99:5.1.10.11.2.1] 1323.2.2 Underground Piping. Piping underground within buildings or embedded in concrete floors or walls shall be installed in a continuous conduit. [NFPA 99:5.1.10.11.2.2]
TABLE 1323.1.5(1) SYSTEM SIZING – FLOW REQUIREMENTS FOR STATION OUTLETS AND INLETS [1]
Notes: 1 Flow rates of station outlets and inlets in accordance with Table 1305.2. 2 The minimum system flow is the average outlets and inlets flow times the number of station outlets and inlets times the diversity percentage.
TABLE 1323.1.5(2) MAXIMUM PERMITTED PRESSURE LOSS IN
MEDICAL GAS AND MEDICAL VACUUM SYSTEMS
For SI units: 1 pound-force per square inch = 6.8947 kPa, 1 inch of mercury = 3.386 kPa
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HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICAL VACUUM SYSTEMS
TABLE 1323.1.4(1) PRESSURE LOSS FOR MEDICAL AIR
TABLE 1323.1.4(2) PRESSURE LOSS FOR NITROGEN
FLOW RATE
(SCFM)1PRESSURE DROP (psi) PER 100 FEET2 Col3 Col4 FLOW RATE
(SCFM)11⁄2 INCH PIPE 3⁄4 INCH PIPE 1 INCH PIPE 0.35 0.004 0.001 – 0.71 0.012 0.003 – 1.06 0.023 0.005 – 1.41 0.037 0.007 – 1.77 0.055 0.011 – 2.12 0.075 0.015 – 2.47 0.097 0.019 – 2.82 0.123 0.024 – 3.18 0. CPC § 506.6 Medium relevance — show source text
Except for ducts used to convey noncorrosive vapors with no particulate, accessible cleanouts shall be provided at 10 foot (3048 mm) intervals and at changes in direction. Access openings shall also be provided for access to sprinklers and other equipment within the duct that require servicing.
506.6 Explosion Venting. Ducts conveying explosive dusts shall have explosion vents, openings protected by anti-flashback swing valves, or rupture diaphragms. Openings to relieve explosive forces shall be located outside the building. Where relief devices cannot provide sufficient pressure relief, ductwork shall be designed to withstand an internal pressure of not less than 100 pounds-force per square inch (psi) (689 kPa).
Where a room or building contains a dust explosion hazard that is external to protected equipment, as defined in NFPA 654, such areas shall be provided with deflagration venting to a safe outside location.
Systems exhausting explosive mixtures shall be protected by an approved explosion relief system in accordance with NFPA 69.
506.7 Supports. Supports shall be of noncombustible materials, and the spacing shall not exceed 12 feet (3658 mm) for 8 inch (203 mm) ducts and 20 feet (6096 mm) for larger ducts.
506.8 Fire Protection. Sprinklers or other fire-protection devices shall be installed within ducts having a cross-sectional dimension exceeding 10 inches (254 mm) where the duct conveys flammable vapors or fumes. Sprinklers shall be installed at 12 foot (3658 mm) intervals in horizontal ducts and at changes in direction. In vertical runs, sprinklers shall be installed at the top and at alternate floor levels.
506.8.1 Loads. Duct supports shall be designed to carry the weight of the duct half filled with material. Where sprinkler protection is provided or cleaning of the duct will be performed, the hanger’s design shall include the weight of any expected liquid accumulation. Duct supports shall be designed to prevent placing loads on connected equipment. [NFPA 91:4.6.1 – 4.6.3]
506.8.2 Corrosion. Hangers and supports exposed to corrosive atmospheres shall be resistant to the corrosive atmospheres. [NFPA 91:4.6.4]
506.8.3 Vibration and Stress. To avoid vibration and stress on the duct, hangers and supports shall be securely fastened to the building or structure. [NFPA 91:4.6.5]
506.8.4 Expansion and Contraction. Hangers and supports shall be designed to allow for expansion and contraction. [NFPA 91:4.6.6]
506.9 Protection from Physical Damage. Ducts and exhaust equipment installed in locations where they are subject to physical damage shall be protected by guards.
506.10 Duct Clearances. Unless the conditions stipulated in Section 506.10.1 or Section 506.10.2 exist, all duct systems and system components shall have a clearance of at least 6 inches (152 mm) from stored combustible materials, and not less than [1] ⁄ 2 of an inch (13 mm) clearance from combustible construction. [NFPA 91:4.7.1]
CPC § 312.2 Medium relevance — show source text
312.2 Installation . . . . . . . . . . . . . . . . . . .52
312.3 Building Sewer and Drainage Piping . . . . . . . . . . . . . . . . . . . . . . .52
312.4 Corrosion, Erosion, and Mechanical Damage . . . . . . . . . . . .52
312.5 Protectively Coated Pipe . . . . . . . .52
312.6 Freezing Protection . . . . . . . . . . . .52
312.7 Fire-Resistant Construction . . . . . .52
312.8 Waterproofing of Openings . . . . . .52
312.9 Steel Nail Plates . . . . . . . . . . . . . . .52
312.10 Sleeves . . . . . . . . . . . . . . . . . . . . . .52
312.11 Structural Members . . . . . . . . . . . .53
312.12 Rodentproofing . . . . . . . . . . . . . . . .53
313.0 Hangers, Supports, and Anchors . . .53
313.1 General . . . . . . . . . . . . . . . . . . . . . .53
313.2 Material . . . . . . . . . . . . . . . . . . . . . .53
313.3 Suspended Piping . . . . . . . . . . . . .53
313.4 Alignment . . . . . . . . . . . . . . . . . . . .53
313.5 Underground Installation . . . . . . . .53
313.6 Hanger Rod Sizes . . . . . . . . . . . . .53
Table 313.6 Hanger Rod Sizes . . . . . . . . . . . . .53
313.7 Gas Piping . . . . . . . . . . . . . . . . . . .53
314.0 Trenching, Excavation, and Backfill . . . . . . . . . . . . . . . . . . . . . .53
314.1 Trenches . . . . . . . . . . . . . . . . . . . . .53
314.2 Tunneling and Driving . . . . . . . . . .53
314.3 Open Trenches . . . . . . . . . . . . . . . .53
314.4 Excavations . . . . . . . . . . . . . . . . . .53
315.0 Joints and Connections . . . . . . . . .54
315.1 Unions . . . . . . . . . . . . . . . . . . . . . .54
315.2 Prohibited Joints and
Connections . . . . . . . . . . . . . . . . . .54
316.0 Increasers and Reducers . . . . . . . .54
316.1 General . . . . . . . . . . . . . . . . . . . . . .54
317.0 Food-Handling Establishments . . . .54
317.1 General . . . . . . . . . . . . . . . . . . . . . .54
318.0 Test Gauges . . . . . . . . . . . . . . . . . .54
CPC § 7.2.1 Medium relevance — show source text
(4) Where piping is encased in a protective pipe sleeve, the annular spaces between the gas piping and the sleeve and between the sleeve and the wall opening shall be sealed.
(5) Piping installed outdoors shall be elevated not less than 3½ inches (89 mm) above the ground.
(6) Sealing materials shall be compatible with the piping and sleeve. [NFPA 54:7.2.1] 1210.3.1 Protective Coating. Where piping is in contact with a material or an atmosphere corrosive to the piping system, the piping and fittings shall be coated with a corrosion-resistant material. Any such coating used on piping or components shall not be considered as adding strength to the system. [NFPA 54:7.2.2] 1210.3.2 Building Structure. The installation of gas piping shall not cause structural stresses within building components to exceed allowable design limits. Approval shall be obtained before any beams or joists are cut or notched. [NFPA 54:7.2.3.1 – 7.2.3.2] 1210.3.3 Gas Piping to be Sloped. Piping for other than dry gas conditions shall be sloped not less than [1] ⁄ 4 inch in 15 feet (6.4 mm in 4.6 m) to prevent traps. [NFPA 54:7.2.4] 1210.3.3.1 Ceiling Locations. Gas piping shall be permitted to be installed in accessible spaces between a fixed ceiling and a dropped ceiling, whether or not such spaces are used as a plenum. Valves shall not be located in such spaces.
Exception: Appliance or equipment shutoff valves required by this code shall be permitted to be installed in accessible spaces containing vented appliances. 1210.3.4 Prohibited Locations. Gas piping inside any building shall not be installed in or through a clothes chute, chimney or gas vent, dumbwaiter, elevator shaft, or air duct, other than combustion air ducts. [NFPA 54:7.2.5]
Exception: Ducts used to provide ventilation air in accordance with Section 506.0 or to above-ceiling spaces in accordance with Section 1210.3.3.1.
1210.3.5 Hangers, Supports, and Anchors. Piping shall be supported with metal pipe hooks, metal pipe straps, metal bands, metal brackets, metal hangers, or building structural components, suitable for the size of piping, of adequate strength and quality, and located at intervals so as to prevent or damp out excessive vibration. Piping shall be anchored to prevent undue strains on connected appliances and equipment and shall not be supported by other piping. Pipe hangers and supports shall conform to the requirements of MSS SP-58. [NFPA 54:7.2.6.1] 1210.3.5.1 Spacing. Spacing of supports in gas piping installations shall not be greater than shown in Table 1210.3.5.1. Spacing of supports of CSST shall be in accordance with the CSST manufacturer’s instructions. [NFPA 54:7.2.6.2]
TABLE 1210.3.5.1
SUPPORT OF PIPING
[NFPA 54: TABLE 7.2.6.2]
CPC § 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.
CPC § 312.0 Medium relevance — show source text
312.0 Plumbing Connections. 312.1 General. Water supply, sanitary drainage, and backflow protection shall be in accordance with the California Plumbing Code .
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code. 313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials.
313.3 Suspended Piping. Suspended piping or tubing shall be supported at intervals not to exceed those shown in Table 313.3.
313.4 Alignment. Piping or tubing shall be supported in such a manner as to maintain its alignment and prevent sagging.
313.5 Underground Installation. Piping or tubing in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 302.0.
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not smaller than those shown in Table 313.6.
TABLE 313.6
HANGER ROD SIZES
PIPE AND TUBE SIZE
(inches)ROD SIZES
(inches)
1⁄2 - 43⁄8
5 - 81⁄2
10 - 125⁄8 For SI units: 1 inch = 25.4 mm
313.7 Gas Piping. Gas piping shall be supported by metal straps or hooks at intervals not to exceed those shown in Table 1310.3.5.1.
314.0 Balancing.
314.1 General. Heating, ventilating, and air-conditioning systems (including hydronic systems) shall be balanced in accordance with one of the following methods:
TABLE 313.6
HANGER ROD SIZES
(1) AABC National Standards for Total System Balance
(2) ACCA Manual B
(3) ASHRAE 111
(4) NEBB Procedural Standards for Testing Adjusting Balancing of Environmental Systems
(5) SMACNA HVAC Systems Testing, Adjusting, and Balancing
315.0 Louvers in Hurricane Prone Regions.
315.1 General. Louvers located in areas within hurricane prone regions that are within 1 mile (2 km) of the coastal mean high water line where the basic wind speed is 110 miles per hour (mi/h) (49.2 m/s) or more; or portions of hurricane-prone regions where the basic wind speed is 120 mi/h (53.6 m/s) or more; or Hawaii, shall be tested in accordance with Section 315.1.1 and Section 315.1.2.
315.1.1 Testing. Louvers that protect air intake or exhaust openings shall be tested in accordance with AMCA 550 for resistance to wind-driven rain.
315.1.2 Impact Resistance Test. Upon request by the Authority Having Jurisdiction, louvers protecting intake and exhaust ventilation ducts that are not fixed in the
CPC § 310.1 Medium relevance — show source text
310.1 Fittings . . . . . . . . . . . . . . . . . . . . . .51
310.2 Drainage and Vent Piping . . . . . . .51
310.3 Waste Connection . . . . . . . . . . . . .51
310.4 Use of Vent and Waste Pipes . . . .51
310.5 Obstruction of Flow . . . . . . . . . . . .51
310.6 Dissimilar Metals . . . . . . . . . . . . . .51
310.7 Direction of Flow . . . . . . . . . . . . . . .51
310.8 Screwed Fittings . . . . . . . . . . . . . . .51
310.9 Female Plastic Connections . . . . . .52
xxviii 2025 CALIFORNIA PLUMBING CODE
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TABLE OF CONTENTS
310.10 ABS and PVC Transition Joints . . .52
310.14 Services/Systems and Utilities . . . .52
310.15 Telephone and Data Equipment Rooms . . . . . . . . . . . . .52
311.0 Independent Systems . . . . . . . . . . .52
311.1 General . . . . . . . . . . . . . . . . . . . . . .52
312.0 Protection of Piping, Tubing, Materials, and Structures . . . . . . . .52
312.1 General . . . . . . . . . . . . . . . . . . . . . .52
312.2 Installation . . . . . . . . . . . . . . . . . . .52
312.3 Building Sewer and Drainage Piping . . . . . . . . . . . . . . . . . . . . . . .52
312.4 Corrosion, Erosion, and Mechanical Damage . . . . . . . . . . . .52
312.5 Protectively Coated Pipe . . . . . . . .52
312.6 Freezing Protection . . . . . . . . . . . .52
312.7 Fire-Resistant Construction . . . . . .52
312.8 Waterproofing of Openings . . . . . .52
312.9 Steel Nail Plates . . . . . . . . . . . . . . .52
312.10 Sleeves . . . . . . . . . . . . . . . . . . . . . .52
312.11 Structural Members . . . . . . . . . . . .53
312.12 Rodentproofing . . . . . . . . . . . . . . . .53
313.0 Hangers, Supports, and Anchors . . .53
313.1 General . . . . . . . . . . . . . . . . . . . . . .53
313.2 Material . . . . . . . . . . . . . . . . . . . . . .53
313.3 Suspended Piping . . . . . . . . . . . . .53
313.4 Alignment . . . . . . . . . . . . . . . . . . . .53
313.5 Underground Installation . . . . . . . .53
CPC § 5.1 Medium relevance — show source text
Cleanouts shall be designed to be watertight and gastight.
5 Testing and Inspection Requirements
5.1 Media
The piping of the building sewer shall be tested with water. The Authority Having Jurisdiction shall be permitted to require the removal of cleanouts, etc., to ascertain whether the pressure has reached all parts of the system.
5.2 Water Test
The system shall be tested by plugging the end of the building sewer at its points of connection to the public sewer or private sewage disposal system and completely filling the building sewer with water from the lowest to the highest point thereof.
5.3 Inspections
The completed piping shall be internally inspected by camera unless waived by the Administrative Authority.
TABLE 1
CLEANOUTS (See Section 4.6.1)
NPS SIZE OF CLEANOUT
(inches)THREADS PER INCH 1.5 1.5 11.5
21.5 11.5
2.52.5 8
32.5 8
4 & larger3.5 8 Note: For SI units: 1 inch = 25 mm
Uniform Plumbing Code References
The following sections of the 2024 Uniform Plumbing Code apply.
105.2 Required Inspections
105.2.2 Other Inspections
105.3 Testing of Systems
301.2 Minimum Standards
309.0 Workmanship
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
CPC § 1210.3.4 Medium relevance — show source text
Exception: Appliance or equipment shutoff valves required by this code shall be permitted to be installed in accessible spaces containing vented appliances. 1210.3.4 Prohibited Locations. Gas piping inside any building shall not be installed in or through a clothes chute, chimney or gas vent, dumbwaiter, elevator shaft, or air duct, other than combustion air ducts. [NFPA 54:7.2.5]
Exception: Ducts used to provide ventilation air in accordance with Section 506.0 or to above-ceiling spaces in accordance with Section 1210.3.3.1.
1210.3.5 Hangers, Supports, and Anchors. Piping shall be supported with metal pipe hooks, metal pipe straps, metal bands, metal brackets, metal hangers, or building structural components, suitable for the size of piping, of adequate strength and quality, and located at intervals so as to prevent or damp out excessive vibration. Piping shall be anchored to prevent undue strains on connected appliances and equipment and shall not be supported by other piping. Pipe hangers and supports shall conform to the requirements of MSS SP-58. [NFPA 54:7.2.6.1] 1210.3.5.1 Spacing. Spacing of supports in gas piping installations shall not be greater than shown in Table 1210.3.5.1. Spacing of supports of CSST shall be in accordance with the CSST manufacturer’s instructions. [NFPA 54:7.2.6.2]
TABLE 1210.3.5.1
SUPPORT OF PIPING
[NFPA 54: TABLE 7.2.6.2]
STEEL PIPE,
NOMINAL SIZE
OF PIPE
(inches)SPACING OF
SUPPORTS
(feet)NOMINAL SIZE
OF TUBING
SMOOTH WALL
(inches O.D.)SPACING OF
SUPPORTS
(feet)
1⁄26 1⁄2 4 3⁄4 or 1 8 5⁄8 or3⁄4 6
11⁄4 or larger
(horizontal)10 7⁄8 or 1
(horizontal)8
11⁄4 or larger
(vertical)Every floor
level1 or larger
(vertical)Every floor
levelFor SI units: 1 inch = 25 mm, 1 foot = 304.8 mm
Frequently asked questions
Which CPC sections cover workmanship, protection and hangers?
Workmanship is primarily in §309.0, protection of piping and related requirements are in §312.0 (with subsections such as §312.1 and §312.9), and hangers/supports/anchors are in §313.0 (including Table 313.3 and Table 313.6).
When are steel nail plates required?
Steel nail plates are required where plastic or copper piping penetrates framing members to within 1 inch of the exposed face; the CPC specifies a minimum No. 18 gauge plate and coverage beyond the pipe diameter in §312.9.
Where do I find hanger spacing and rod‑size tables for piping?
Hanger spacing and minimum hanger rod sizes are given in Table 313.3 and Table 313.6 (see §313.0 and related text); gas‑piping support spacing is also referenced in §1210.3.5 and its support spacing table.
More in California Plumbing Code
- Administration
- Definitions
- General Regulations
- Plumbing Fixtures and Fixture Fittings
- Water Heaters
- Water Supply and Distribution
- Sanitary Drainage (Drain, Waste, and Vent)
- Indirect Wastes
- Vents
- Traps and Interceptors
- Storm Drainage
- Fuel Gas Piping
- Health Care Facilities — Medical Gas and Medical Vacuum Systems
- Alternate Water Sources and Nonpotable Rainwater Catchment Systems
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