CPC · California Plumbing Code
How must piping be supported, anchored, and hung?
Piping must be supported and anchored so it carries its own weight (and contents) without sagging or stressing connections, using hangers/hardware sized per CPC Table 313.6 and supported at intervals required by Table 313.3; seismic anchorage follows the building code per §313.8 — consult the CPC tables and your AHJ for the exact spacing and seismic details.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
In plain English: Piping and tubing must be supported, hung, and anchored so it carries its own weight and contents without undue strain, maintains alignment (no sagging), is isolated from incompatible materials, and follows manufacturer instructions and Authority Having Jurisdiction requirements. Seismic restraint and bracing are required where applicable by the building code (for special occupancies see the OSHPD note). These general mandates come from § 313.0 through § 313.6 and the OSHPD note § 313.8 in the CPC.
The single most important rule: piping must be supported and anchored so it will not sag, impose undue stress on connected equipment, or be damaged — and seismic anchorage follows the building code where required. § 313.1, § 313.2, § 313.4, § 313.8.
Requirements in detail
1) General obligations and scope
- The CPC requires that piping, tubing, fixtures, appliances, and appurtenances be supported in accordance with the Code, the manufacturer’s installation instructions, and the Authority Having Jurisdiction. See § 313.1.
- Seismic restraints: where seismic anchorage or bracing applies, the building code controls; CPC § 313.8 points users to Title 24, Part 2 (CBC/OSHPD) for those requirements. § 313.8.
2) Materials and isolation
- Hangers, supports, and anchors must be of sufficient strength to carry the pipe/tube and its contents and must isolate piping from incompatible materials. See § 313.2.
3) Suspended piping — spacing (what the code says)
- Suspended piping must be supported at intervals not to exceed the limits shown in Table 313.3; the CPC text states this requirement under § 313.3. However, the specific numeric spacings listed in Table 313.3 are not present in the provided file excerpts, so consult the printed CPC Table 313.3 or your AHJ for the exact maximum spacing values. § 313.3.
4) Alignment, underground, and other basics
- Supports must maintain alignment and prevent sagging — § 313.4.
- Underground piping must be laid on a firm bed for its entire length (unless alternate approved support is provided) — § 313.5.
5) Hanger rod sizing (decision‑relevant dimensions)
The CPC provides minimum hanger rod sizes in § 313.6 and Table 313.6; those values are retrievable in the provided files and are reproduced below with the controlling code reference.
| Pipe/tube nominal size (inches) | Minimum hanger rod size (inches) | Code Reference |
|---|---|---|
| 1/2 – 4 | 3/8 | § 313.6 |
| 5 – 8 | 1/2 | § 313.6 |
| 10 – 12 | 5/8 | § 313.6 |
- Bold values above are the code minimums; use larger/higher‑capacity hardware if pipe weight, hanger spacing, or special conditions dictate. § 313.6.
6) Gas piping and other referenced tables
- The CPC separately addresses fuel‑gas piping support: gas piping support intervals are governed by a fuel‑gas table (Table 1210.3.5.1) and by § 1210.3.5; spacing values for gas piping are available in that table (which is included in the provided excerpts). See § 313.7 (cross‑referencing gas piping) and § 1210.3.5 / Table 1210.3.5.1 for gas spacing details.
7) Expansion, contraction, and movement
- Supports, hangers, and anchors must be installed so they do not interfere with free thermal expansion/contraction of piping between anchors; the supporting system must not disengage due to pipe movement. (This specific expansion/contraction text appears in the gas piping / fuel section but applies as general good practice; see § 1210.3.5.2 for the explicit statement regarding movement).
8) Seismic anchorage (special occupancies)
- For OSHPD (hospital) and similar categories, § 313.8 directs designers to the California Building Code/OSHPD rules for seismic anchorage, bracing, and displacement accommodations. You must follow CBC/OSHPD for seismic calculations and detailing where applicable. § 313.8.
Exceptions & special cases
- If the manufacturer’s installation instructions specify support spacing or anchorage details, follow those instructions in addition to the CPC and AHJ requirements — § 313.1.
- Fuel gas piping: supports and spacing may follow separate NFPA‑based tables incorporated in the CPC (see § 1210.3.5 and Table 1210.3.5.1) — consult those provisions for gas systems.
- Seismic rules: where seismic anchorage is required (e.g., OSHPD projects), use the CBC/OSHPD provisions referenced by § 313.8 — do not rely solely on Chapter 3 hangers/supports rules for seismic design.
Common mistakes
- Assuming a one‑size‑fits‑all hanger/hanger rod: the CPC sets minimum rod sizes by pipe nominal size (§ 313.6) — don’t undersize rods.
- Forgetting to isolate piping from incompatible materials (corrosion/galvanic action) — required by § 313.2.
- Overlooking manufacturer instructions or AHJ direction; CPC explicitly requires following both (§ 313.1).
- Relying on a memory of maximum support spacing without checking Table 313.3 — the CPC requires following Table 313.3 for suspended piping; specific spacing numbers were not available in the supplied excerpts, so verify the table in your copy of the CPC or with the AHJ. § 313.3.
- Omitting seismic anchorage where building code/OSHPD requires it — CPC points this out in § 313.8.
Worked example — concrete scenario (numbers grounded in code excerpts)
Scenario: You are hanging a horizontal 3‑inch water distribution pipe in a commercial ceiling and must pick a hanger rod and check spacing.
Hanger rod size: For pipe nominal size between 1/2 – 4 inches, the CPC minimum hanger rod size is 3/8 inch. Use at least 3/8‑inch rod for a 3‑inch pipe per § 313.6 / Table 313.6.
Spacing: The CPC requires suspended piping be supported at intervals not to exceed those shown in Table 313.3 (§ 313.3). The specific maximum spacing values from Table 313.3 were not present in the provided file excerpts; therefore you must consult the printed CPC Table 313.3 or your AHJ to determine the permitted spacing for a horizontal 3‑inch pipe. § 313.3.
Other checks: Confirm that hangers/supports are rated for the load (per § 313.2), do not transmit undue stress to connected equipment (per § 313.1), and allow for thermal movement (see expansion/movement guidance in related sections). If the building requires seismic restraints for this piping, follow the building code/OSHPD direction invoked by § 313.8.
Related provisions
- § 313.1 — General support requirements and relation to manufacturer/AHJ.
- § 313.2 — Material strength and isolation from incompatible materials.
- § 313.3 — Suspended piping support intervals (see Table 313.3).
- § 313.4 — Alignment and prevention of sagging.
- § 313.6 — Hanger rod sizes (Table 313.6).
- § 313.7 — Fuel gas piping cross‑reference for supports.
- § 313.8 — OSHPD / CBC reference for seismic anchorage and bracing.
- § 1210.3.5 and Table 1210.3.5.1 — Fuel gas piping hangers, supports, and spacing (useful when working on gas piping).
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 312.0 High 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 § 1210.3.4 High 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
CPC § 1310.3.4 High relevance — show source text
1310.3.4 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 701.0 or to above-ceiling spaces in accordance with Section 1310.3.3.1.
1310.3.5 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]
1310.3.5.1 Spacing. Spacing of supports in gas piping installations shall not be greater than shown in Table 1310.3.5.1. Spacing of supports of CSST shall be in accordance with the CSST manufac turer’s instructions. [NFPA 54:7.2.6.2]
TABLE 1310.3.5.1
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)1⁄2 6 1⁄2 4
3⁄4 or 18 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
1310.3.5.2 Expansion and Contraction. Supports, hangers, and anchors shall be installed so as not to interfere with the free expansion and contraction of the piping between anchors. All parts of the supporting system shall be designed and installed so they are not disengaged by movement of the supported piping. [NFPA 54:7.2.6.3]
1310.3.5.3 Piping on Roofs. Gas piping installed on the roof surfaces shall be supported in accordance with Table 1310.3.5.1. Gas piping shall be elevated not less than 3½ inches (89 mm) above the roof surface. [NFPA 54:7.2.6.4.1, 7.2.6.4.2]
CPC § 313.0 High relevance — show source text
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, fixtures, 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 shall be supported at intervals not to exceed those shown in Table 313.3. 313.4 Alignment. Piping shall be supported in such a manner as to maintain its alignment and prevent sagging. 313.5 Underground Installation. Piping 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 301.2.
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 SIZE
(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 1210.3.5.1.
313.8 [OSHPD 1, 2, 3, 4 & 5] Refer to Title 24, Part 2 of the California Building Code for seismic anchorage and bracing requirements and accommodations for building displace-
ments.
314.0 Trenching, Excavation, and Backfill.
314.1 Trenches. Trenches deeper than the footing of a building or structure, and paralleling the same, shall be located not less than 45 degrees (0.79 rad) from the bottom exterior edge of the footing, or as approved in accordance with Section 301.0.
314.2 Tunneling and Driving. Tunneling and driving shall be permitted to be done in yards, courts, or driveways of a building site. Where sufficient depth is available to permit, tunnels shall be permitted to be used between open-cut trenches.
Tunnels shall have a clear height of 2 feet (610 mm) above the pipe and shall be limited in length to one-half the depth of the trench, with a maximum length of 8 feet (2438 mm). Where pipes are driven, the drive pipe shall be not less than one size larger than the pipe to be laid.
314.3 Open Trenches. Excavations required to be made for the installation of a building drainage system or part thereof, within the walls of a building, shall be open trench work and shall be kept open until the piping has been inspected, tested, and accepted.
CPC § 1210.3.5.1 High relevance — show source text
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
1210.3.5.2 Expansion and Contraction. Supports, hangers, and anchors shall be installed so as not to interfere with the free expansion and contraction of the piping between anchors. All parts of the supporting system shall be designed and installed so they are not disengaged by movement of the supported piping. [NFPA 54:7.2.6.3] 1210.3.5.3 Piping on Roofs. Gas piping installed on the roof surfaces shall be supported in accordance with Table 1210.3.5.1. Gas piping shall be elevated not less than 3½ inches (89 mm) above the roof surface. [NFPA 54:7.2.6.4.1, 7.2.6.4.2] 1210.4 Concealed Piping in Buildings. Gas piping in concealed locations shall be installed in accordance with this section. [NFPA 54:7.3.1]
TABLE 1210.3.5.1
SUPPORT OF PIPING
[NFPA 54: TABLE 7.2.6.2]
For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm
2025 CALIFORNIA PLUMBING CODE 225
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FUEL GAS PIPING
1210.4.1 Connections. Where gas piping is to be concealed, connections shall be of the following type:
(1) Pipe fittings such as elbows, tees, couplings, and right/left nipple/couplings.
(2) Joining tubing by brazing (see Section 1208.5.9.1).
(3) Press-connect fittings listed to ANSI LC 4/CSA 6.32.
(4) CSST fittings listed to CSA/ANSI LC 1/CSA 6.26.
CPC § 1210.4.3. High relevance — show source text
Fuel gas piping shall be protected in accordance with Section 1210.4.3.
312.10 Sleeves. Sleeves shall be provided to protect piping through concrete and masonry walls, and concrete floors. Exception: Sleeves shall not be required where openings are drilled or bored.
52 2025 CALIFORNIA PLUMBING CODE
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GENERAL REGULATIONS
312.10.1 Building Loads. Piping through concrete or masonry walls shall not be subject to a load from building construction.
312.10.2 Exterior Walls. In exterior walls, annular space between sleeves and pipes shall be sealed and made watertight, as approved by the Authority Having Jurisdiction. A penetration through fire-resistive construction shall be in accordance with Section 312.7.
312.10.3 Firewalls. A pipe sleeve through a firewall shall have space around the pipe completely sealed with an approved fire-resistive material in accordance with other codes.
312.11 Structural Members. A structural member weakened or impaired by cutting, notching, or otherwise shall be reinforced, repaired, or replaced so as to be left in a safe structural condition in accordance with the requirements of the California Building Code or California Residential Code . 312.12 Rodentproofing. Strainer plates on drain inlets shall be designed and installed so that no opening exceeds [1] ⁄ 2 of an inch (12.7 mm) in the least dimension.
312.12.1 Meter Boxes. Meter boxes shall be con structed in such a manner as to restrict rodents or vermin from entering a building by following the service pipes from the box into the building. 312.12.2 Metal Collars. In or on buildings where openings have been made in walls, floors, or ceilings for the passage of pipes, such openings shall be closed and protected by the installation of approved metal collars securely fastened to the adjoining structure. 312.12.3 Tub Waste Openings. Tub waste openings in framed construction to crawl spaces at or below the first floor shall be protected by the installation of approved metal collars or metal screen securely fastened to the adjoining structure with no opening exceeding [1] ⁄ 2 of an inch (12.7 mm) in the least dimension.
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, fixtures, 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 shall be supported at intervals not to exceed those shown in Table 313.3. 313.4 Alignment. Piping shall be supported in such a manner as to maintain its alignment and prevent sagging. 313.5 Underground Installation. Piping 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 301.2.
CPC § 7.2.1 High 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 § 1617.12.16 High relevance — show source text
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
STRUCTURAL DESIGN
1617.12.16 ASCE 7, Section 13.6.7.3. Replace ASCE 7, Section 13.6.7.3 with the following:
13.6.7.3 Additional provisions for piping and tubing systems. A) Design for the seismic forces of Section 13.3 shall not be required for piping systems where flexible connections, expansion loops or other assemblies are provided to accommodate the relative displacement between component and piping, where the piping system is positively attached to the structure, and where any of the following conditions apply:
- Trapeze assemblies are supported by [3] / 8 -inch (10 mm) or [1] / 2 -inch (13-mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the pipe support point to the connection at the supporting structure, and no single pipe exceeds the diameter limits set forth in item 2b or 2 inches (50 mm) where I p is greater than 1.0 and the total weight supported by any single trapeze is 100 pounds (445 N) or less; or 2. Piping is supported by rod hangers and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact; or pipes are supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, where each hanger in the pipe run is 12 inches (305 mm) or less in length from the pipe support point to the connection at the supporting structure, and the total weight supported by any single hanger is 50 pounds (220 N) or less. In addition, the following limitations on the size of piping shall be observed: a. In structures assigned to Seismic Design Category D, E or F where I p is greater than 1.0, the nominal pipe size shall be 1 inch (25 mm) or less. b. In structures assigned to Seismic Design Category D, E or F where I p = 1.0, the nominal pipe size shall be 3 inches (80 mm) or less. 3. Pneumatic tube systems supported with trapeze assemblies using [3] / 8 -inch (10 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the tube support point to the connection at the supporting structure and the total weight supported by any single trapeze is 100 pounds (445 N) or less. 4. Pneumatic tube systems supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the run is 12 inches (305 mm) or less in length from the tube support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. B) Flexible connections in piping required in Section 13.6.7.3 are not required where pipe is rigidly attached to the same floor or wall that provides vertical and lateral support for the equipment, or to a fixture. C) Flexible connections in piping are required at seismic separation joints and shall be detailed to accommodate the seis- mic relative displacements at connections.
CPC § 1310.3.1 High relevance — show source text
1310.3.1 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]
1310.3.2 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]
1310.3.3 Gas Piping to be Sloped. Piping for other than dry gas conditions shall be sloped not less than [1] ⁄ 4 inch in 15 feet (1.4 mm/m) to prevent traps. [NFPA 54:7.2.4]
1310.3.3.1 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.
1310.3.4 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 701.0 or to above-ceiling spaces in accordance with Section 1310.3.3.1.
1310.3.5 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]
1310.3.5.1 Spacing. Spacing of supports in gas piping installations shall not be greater than shown in Table 1310.3.5.1. Spacing of supports of CSST shall be in accordance with the CSST manufac turer’s instructions. [NFPA 54:7.2.6.2]
TABLE 1310.3.5.1
SUPPORT OF PIPING
[NFPA 54: TABLE 7.2.6.2]
CPC § 304.8 High relevance — show source text
STEEL PIPE,
NOMINAL SIZE
OF PIPE(inches)SPACING OF
SUPPORTS
(feet)NOMINAL SIZE
OF TUBING
SMOOTH WALL
(inches O.D.)SPACING OF
SUPPORTS
(feet)1⁄2 6 1⁄2 4
3⁄4 or 18 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
1310.3.5.2 Expansion and Contraction. Supports, hangers, and anchors shall be installed so as not to interfere with the free expansion and contraction of the piping between anchors. All parts of the supporting system shall be designed and installed so they are not disengaged by movement of the supported piping. [NFPA 54:7.2.6.3]
1310.3.5.3 Piping on Roofs. Gas piping installed on the roof surfaces shall be supported in accordance with Table 1310.3.5.1. Gas piping shall be elevated not less than 3½ inches (89 mm) above the roof surface. [NFPA 54:7.2.6.4.1, 7.2.6.4.2]
1310.3.6 Removal of Piping. Where piping containing gas is to be removed, the line shall be first disconnected from sources of gas and then thoroughly purged with air, water, or inert gas before cutting or welding is done. 1310.4 Concealed Piping in Buildings. Gas piping in concealed locations shall be installed in accordance with this section. [NFPA 54:7.3.1]
1310.4.1 Connections. Where gas piping is to be concealed, connections shall be of the following type:
(1) Pipe fittings, such as elbows, tees, couplings, and right/left nipple/couplings.
(2) Joining tubing by brazing (see Section 1308.4.7.1).
(3) Press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32.
(4) CSST fittings listed to CSA/ANSI LC 1/CSA 6.26.
(5) Where necessary to insert fittings in gas pipe that has been installed in a concealed location, the pipe shall be reconnected by welding, flanges, or the use of a right/left nipple/coupling.
1310.4.2 Piping in Partitions. Concealed gas piping shall not be located in solid partitions. [NFPA 54:7.3.3]
1310.4.3 Tubing in Partitions. This provision shall not apply to tubing that pierces walls, floors, or partitions. Tubing installed vertically and horizontally inside hollow walls or partitions without protection along its entire concealed length shall meet the following requirements:
(1) A steel striker barrier not less than 0.0508 of an inch (1.3 mm) thick, or equivalent, is installed between
CPC § 1617A.1.26 High relevance — show source text
1617A.1.26 ASCE 7, Section 13.6.7.3. Replace ASCE 7, Section 13.6.7.3 with the following:
13.6.7.3 Additional Provisions for Piping and Tubing Systems. A) Design for the seismic forces of Section 13.3 shall not be required for piping systems where flexible connections, expansion loops or other assemblies are provided to accommodate the relative displacement between component and piping, where the piping system is positively attached to the structure, and where any of the following conditions apply:
- Trapeze assemblies are supported by [3] / 8 -inch (10 mm) or [1] / 2 -inch (13 mm) diameter rod hangers not exceeding 12 inches (305 mm) in length from the pipe support point to the connection at the supporting structure, and no single pipe exceeds the diameter limits set forth in item 2b below or 2 inches (50 mm) where I p is greater than 1.0 and the total weight supported by any single trapeze is 100 pounds (445 N) or less; or 2. Piping is supported by rod hangers and provisions are made to avoid impact with other structural or nonstructural components or to protect the piping in the event of such impact; or pipes are supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, where each hanger in the pipe run is 12 inches (305 mm) or less in length from the pipe support point to the connection at the supporting structure, and the total weight supported by any single hanger is 50 pounds (220 N) or less. In addition, the following limitations on the size of piping shall be observed: a. In structures assigned to Seismic Design Category D, E or F where I p is greater than 1.0, the nominal pipe size shall be 1 inch (25 mm) or less. b. In structures assigned to Seismic Design Category D, E or F where I p = 1.0, the nominal pipe size shall be 3 inches (80 mm) or less. 3. Pneumatic tube systems supported with trapeze assemblies using [3] / 8 inch (10 mm) in diameter rod hangers not exceeding 12 inches (305 mm) in length from the tube support point to the connection at the supporting structure and the total weight supported by any single trapeze is 100 pounds (445 N) or less. 4. Pneumatic tube systems supported by individual rod hangers [3] / 8 inch (10 mm) or [1] / 2 inch (13 mm) in diameter, and each hanger in the run is 12 inches (305 mm) or less in length from the tube support point to the connection at the supporting structure, and the total weight supported by any single rod is 50 pounds (220 N) or less. B) Flexible connections in piping required in Section 13.6.7.3 are not required where pipe is rigidly attached to the same floor or wall that provides vertical and lateral support for the equipment, or to a fixture. C) Flexible connections in piping are required at seismic separation joints and shall be detailed to accommodate the seis- mic relative displacements at connections.
CPC § 3109F.3 High relevance — show source text
_ 5. A guide or lateral restraint shall be provided just past the elbow where a pipe changes direction in order to minimize excessive axial stress (N). 6. Piping shall be routed to allow for movement due to thermal expansion and seismic displacement, without exceeding the allowable stresses in the supports, and anchor connections (see Section 3109F.3) (N/E). 7. Plastic piping shall not be used unless designated for oil service (N/E). 8. If a flanged connection exists within 20 pipe diameters from the end of any replaced section, the pipe shall be replaced up to and including the flange. 9. Pipelines shall be seamless, electric-resistance-welded or electric-fusion-welded (N). 10. Piping greater than 2 inches in diameter shall be butt-welded. Piping 2 inches and smaller shall be socket welded or threaded. 11. Pipeline connections directly over the water shall be welded (N). Flanged connections not over water shall have secondary containment (N). 12. Pipelines that do not have a valid and certified Static Liquid Pressure Test (SLPT) [9.4] shall be marked “OUT OF SERVICE.” Out- of-service piping and pipelines shall be purged, gas-freed and physically isolated from sources of oil. 13. If a pipeline is “out-of-service” for 3 or more years, it will require a valid and certified Static Liquid Pressure Test (SLPT) and API 570 inspection [9.4] prior to Division approval for re-use (E). 14. New piping and pipeline systems require a valid and certified Static Liquid Pressure Test (SLPT) [9.4] and Division approval, prior to operation.
3109F.3 Pipeline stress analysis (N/E). Pipeline stress analysis shall be performed for: 1. New piping and pipelines 2. Significant rerouting/relocation of existing piping 3. Any replacement of “not in-kind” piping 4. Any significant rearrangement or replacement of “not in-kind” anchors and/or supports 5. Significant seismic displacements calculated from the structural and/or geotechnical assessments
Pipeline stress analysis shall be performed in accordance with ASME B31.4 [9.3], considering all relevant loads and corresponding displacements determined from the structural analysis and/or geotechnical analysis described in Sections 3104F and 3106F, respec- tively. Seismic loading of above-grade pipelines may be analyzed in accordance with ASME B31.E [9.5] with seismic loads computed from Section 3104F.5.4.1.
For pipelines spanning between seismically isolated structures (Section 3104F.1.3) and/or varying geotechnical conditions, evalua- tion of the relative movement of pipelines and supports and varying seismic accelerations shall be considered, including phase differences.
Flexibility analysis for piping, considering supports, shall be performed in accordance with ASME B31.4 [9.3] by using the largest temperature differential imposed by normal operation, start-up, shutdown or abnormal conditions. Thermal loads shall be based upon maximum and minimum local temperatures; heat traced piping shall use the maximum attainable temperature of the heat tracing system.
Section 3106F.12 provides additional considerations for underwater seafloor pipelines.
31F-84 2025 CALIFORNIA BUILDING CODE
CPC § 0.03 High relevance — show source text
(5) A closet, bathroom, toilet room, kitchen, garage, boiler room, furnace room, or unconditioned attic.
(6) Rooms or spaces containing a fuel-burning appliance therein. Where such room or space serves as source of return-air.
Exceptions:
(1) This shall not apply to fireplaces, fireplace appliances, residential cooking appliances, direct vent appliances, enclosed furnaces, and domestic-type clothes dryers installed within the room or space.
(2) This shall not apply to a gravity-type or listed vented wall heating or cooling air system.
(3) This shall not apply to a blower-type heating or cooling air system installed in accordance with the following requirements:
(a) Where the return air is taken from a room or space having a volume exceeding 1 cubic foot (0.03 m [3] ) for each 10 Btu/h (0.003 kW) fuel input rating of fuel-burning appliances therein.
(b) Not less than 75 percent of the supply air is discharged back into the same room or space.
(c) Return-air inlets shall not be located within 10 feet (3048 mm) from an appliance firebox or draft diverter in the same enclosed room or confined space.
311.4 Return-Air Limitations. Return air from one dwelling unit shall not discharge into another dwelling unit through the heating or cooling air system.
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GENERAL REGULATIONS
311.5 California Energy Code Requirements for Res- idential Air Filtration. In mechanically ventilated residen- tial buildings, air filters shall be provided to clean outdoor air and return air prior to its delivery to occupied spaces where specified in California Energy Code Sections 150.0(m)12 and 160.2(b). The air filters shall comply with California Energy Code requirements for labeling, ventilation system design and installation, air filter efficacy, and air filter pressure drop.
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.
CPC § 37-14 Medium relevance — show source text
- It is accept-_ able to use ballasts for seismic or wind bracing supports and attachments and limit the design to overturning only without the consideration of sliding, unless directly or indirectly supported by the building structure. 3) Anticipated duration of use must be specified. b. Wind design speeds may be reduced as prescribed in ASCE 37-14 or other standard approved by OSHPD. c. Piping, conductors and ductwork shall be supported. Seismic design for supports and attachments of piping, conductors and ductwork is not required.
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STRUCTURAL DESIGN
7. Other Equipment: Equipment shall be anchored where any of the following apply: a. [OSHPD 1, 2, 4 & 5] Essential to hospital operations and weight of equipment is greater than 100 pounds (45 kg).
[DSA-SS] Weight of equipment is greater than 100 pounds (45 kg) and essential to operations for emergency preparedness, communications and operations centers, and other facilities required for emergency response of state-owned essential services buildings as defined in the California Administrative Code (Title 24, Part 1, CCR) Section 4-207 and all structures required for their continuous operation or access/egress. b. [OSHPD 1, 2, 4 & 5] Could fall within the patient care vicinity as defined in Article 517.2 of the California Electrical Code.
c. Could fall and block a required means of egress. d. [OSHPD 1, 2, 4 & 5] Weight of equipment is greater than 400 pounds (181.4 kg). e. [DSA-SS] Weight of equipment is greater than 400 pounds (181.4 kg) or center of mass is located greater than 4 feet (1219 mm) above the finished floor or roof level that directly supports the component.
[OSHPD 1, 2, 4 & 5] Weight of equipment is greater than 200 pounds (90 kg) and center of mass located greater than 4 feet (1219 mm) measured from the finished floor.
8. Equipment with hazardous contents. 9. Other architectural, mechanical and electrical components stated in Chapter 13. [DSA-SS] Cabinets shall be restrained in a manner approved by the enforcement agency if they could fall and block a required means of egress. 10. Wall-, Roof- or Floor-Hung Equipment: Seismic design and seismic details shall be provided for wall-, roof- or floor- hung nonstructural components and equipment when the component weighs more than 20 pounds (9 kg) or, in the case of a distribution system, 5 pounds per foot (73 N/m).
[OSHPD 1, 2, 4 & 5] Exemptions:
1. Furniture except storage cabinets as noted in Table 13.5-1. 2. Nonstructural components and equipment, that are attached to the building, provided that the component weighs 20 _pounds (9 kg) or less or, in the case of a distribution system, 5 pounds per foot (73 N/m) or less.
CPC § 37-14 Medium relevance — show source text
[DSA-SS] Countertop Equipment: Countertop equipment shall be subject to the same anchorage or restraint require- ments for fixed or movable equipment, as applicable. Countertop equipment shall also be subject to the same requirements as mobile or other equipment if weight of equipment is greater than 100 pounds (45 kg) and has a center of mass located 4 feet (1219 mm) or more above the adjacent floor level or if equipment could fall and block a required means of egress. 5. [OSHPD 1, 2, 4 & 5] Temporary Equipment: Equipment for uses greater than 30 days but less than or equal to 180 days and where this section requires supports and attachments, the following shall apply: a. Seismic design for supports and attachments for temporary equipment shall meet the requirements of Chapter 13; however, the calculated F p may be reduced by 50 percent. It is acceptable to use ballasts for seismic bracing supports and attachments and to limit the design criteria to overturning unless directly or indirectly supported by the building structure.
b. Wind design speeds may be reduced as prescribed in ASCE 37-14 or other standard approved by OSHPD. c. Temporary piping, conductors and ductwork shall be supported. Seismic design for supports and attachments of temporary piping, conductors and ductwork is not required. 6. [OSHPD 1, 2, 4 & 5] Interim Equipment: a. Seismic design for supports and attachments for interim equipment shall meet the requirements of Chapter 13 with the following modifications; 1) The calculated F p used in the design may be reduced by 50 percent. 2) It is accept- able to use ballasts for seismic or wind bracing supports and attachments and limit the design to overturning only without the consideration of sliding, unless directly or indirectly supported by the building structure. 3) Anticipated duration of use must be specified. b. Wind design speeds may be reduced as prescribed in ASCE 37-14 or other standard approved by OSHPD. c. Piping, conductors and ductwork shall be supported. Seismic design for supports and attachments of piping, conductors and ductwork is not required.
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STRUCTURAL DESIGN
7. Other Equipment: Equipment shall be anchored where any of the following apply: a. [OSHPD 1, 2, 4 & 5] Essential to hospital operations and weight of equipment is greater than 100 pounds (45 kg).
[DSA-SS] Weight of equipment is greater than 100 pounds (45 kg) and essential to operations for emergency preparedness, communications and operations centers, and other facilities required for emergency response of state-owned essential services buildings as defined in the California Administrative Code (Title 24, Part 1, CCR) Section 4-207 and all structures required for their continuous operation or access/egress. b. [OSHPD 1, 2, 4 & 5] Could fall within the patient care vicinity as defined in Article 517.2 of the California Electrical Code.
CPC § 402.4 Medium relevance — show source text
402.4 Wall-Hung Fixtures. Wall-hung fixtures shall be rigidly supported by metal supporting members so that no strain is transmitted to the connections. Floor-affixed supports for off-the-floor plumbing fixtures for public use shall comply with ASME A112.6.1M. Framing-affixed supports for off-thefloor water closets with concealed tanks shall comply with ASME A112.6.2. Flush tanks and similar appurtenances shall be secured by approved non-corrosive screws or bolts.
402.5 Setting. Fixtures shall be set level and in proper alignment with reference to adjacent walls. No water closet or bidet shall be set closer than 15 inches (381 mm) from its center to a side wall or obstruction or closer than 30 inches (762 mm) center to center to a similar fixture. The clear space in front of a water closet, lavatory, or bidet shall be not less than 24 inches (610 mm). No urinal shall be set closer than 12 inches (305 mm) from its center to a side wall or partition or closer than 24 inches (610 mm) center to center.
Exception: The installation of paper dispensers or accessibility grab bars shall not be considered obstructions.
402.6 Flanged Fixture Connections. Fixture connections between drainage pipes and water closets, floor outlet service sinks and urinals shall be made using an approved copper alloy, hard lead, ABS, PVC, or iron flanges caulked, soldered, solvent cemented; rubber compression gaskets; or screwed to the drainage pipe. The connection shall be bolted with an approved gasket, washer, or setting compound between the fixture and the connection. The bottom of the flange shall be set on the top of the finished floor.
Wall-mounted water closet fixtures shall be securely bolted to an approved carrier fitting. The approved carrier fitting shall be securely attached to the structure. The connecting pipe between the carrier fitting and the fixture shall be an approved material and designed to accommodate an adequately sized gasket. Gasket material shall be neoprene, felt, or similar approved types.
402.6.1 Closet Rings (Closet Flanges). Closet rings (closet flanges) for water closets or similar fixtures shall be of an approved type and shall be copper alloy, copper, hard lead, cast-iron, galvanized malleable iron,
2025 CALIFORNIA PLUMBING CODE 59
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PLUMBING FIXTURES AND FIXTURE FITTINGS
ABS, PVC, or other approved materials. Closet rings (closet flanges) shall be approximately 7 inches (178 mm) in diameter and, where installed, shall, together with the soil pipe, present a 1 [1] ⁄ 2 inch (38 mm) wide flange or face to receive the fixture gasket or closet seal.
Caulked-on closet rings (closet flanges) shall be not less than [1] ⁄ 4 of an inch (6.4 mm) thick and not less than 2 inches (51 mm) in overall depth.
Closet rings (closet flanges) shall be burned or soldered to lead bends or stubs, shall be caulked to cast-iron soil pipe, shall be solvent cemented to ABS and PVC, and shall be screwed or fastened in an approved manner to other materials.
Frequently asked questions
Can I use a smaller hanger rod if the run is short?
No. The CPC sets minimum hanger rod sizes by pipe nominal size in § 313.6 (Table 313.6). Use at least the listed minimum; you may use larger rods if loads or conditions require.
Where do I find the maximum spacing for suspended piping?
The CPC requires support spacing per Table 313.3 referenced in § 313.3. The specific numeric spacings were not available in the provided excerpts — consult your copy of Table 313.3 or the AHJ.
What if the pipe manufacturer’s instructions differ from the CPC?
Follow both: the Code requires the installation to follow the Code, the manufacturer’s instructions, and the AHJ direction — § 313.1. Resolve conflicts with the AHJ.
Do I need seismic hangers for every project?
Seismic restraints are required where the building code or project category mandates them. § 313.8 expressly refers seismic anchorage/bracing to the California Building Code/OSHPD provisions; check those rules for your project.
Are special rules for gas piping supports different?
Yes — fuel gas piping support and spacing are governed by § 1210.3.5 and Table 1210.3.5.1 (and CSST manufacturer instructions where applicable). The CPC references that table in § 313.7.
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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