CMC · California Mechanical Code
Hangers, supports and managing thermal expansion
The California Mechanical Code requires hydronic piping be installed to avoid undue stresses from thermal expansion and settlement (§ 1210.2) and to be supported per Section 313.0 with additional supports for equipment (§ 1210.3). Small equipment connections under 2½ in (64 mm) must have a flexible connector or three 90° offsets, and radiant plates need a 1/4 in (6.4 mm) gap. Follow manufacturer instructions for equipment supports and allow movement between anchors.
Last reviewed: July 6, 2026
What the code requires — plain English
Pipes and tubing used in hydronic systems must be installed so they are not subjected to undue strains or stresses and must include provisions for expansion, contraction, and structural settlement — § 1210.2.
Piping and tubing must be supported in accordance with the applicable hanger/support rules (see Section 313.0) and equipment that is part of the piping system must receive additional supported per the code and the manufacturer’s instructions — § 1210.3.
The single most important rule: design supports and anchors so the piping is free to expand and contract between anchors — do not create fixed restraints that cause undue stress.
Requirements in detail
Expansion and contraction (what the code says)
- The code requires that piping/tubing installations include measures to prevent undue strains or stresses from thermal movement or building settlement. § 1210.2 is the controlling provision.
- For small connections to heat-exchange equipment, the code prescribes specific flexibility at the connection: pipe connections less than 2½ inches (64 mm) to heating coils, cooling coils, humidifiers and similar equipment must use either a flexible connector or three (3) 90-degree offsets located close to the connection. § 1210.2.
Hangers, supports and equipment loads
- Pipes and tubing shall be supported in accordance with Section 313.0; equipment that is part of the piping system must be given additional support per the code and the equipment manufacturer’s instructions — § 1210.3.
- Radiant systems using heat-transfer or emission plates must leave a gap of at least 1/4 inch (6.4 mm) between adjacent plates (this is a support/installation requirement contained in the same section). § 1210.3.
Decision‑relevant dimensions & values
| Item / decision | Dimension or value to use | Code Reference |
|---|---|---|
| Minimum flexibility for small equipment connections | Connections < 2½ inches (64 mm): use flexible connector or three 90° offsets | § 1210.2 |
| Radiant plate spacing | Gap ≥ 1/4 inch (6.4 mm) between adjacent plates | § 1210.3 |
| Overall support practice | Support piping in accordance with Section 313.0; provide added support for piping‑mounted equipment per manufacturer | § 1210.3 |
How to interpret “not be subject to undue strains or stresses”
- Provide flexible elements or offsets at equipment connections when the code prescribes them (see the 2½ in / 64 mm threshold). § 1210.2.
- Locate anchors to intentionally control where the run is fixed so thermal displacement occurs where designed (the code requires provisions for expansion/contraction between anchors). § 1210.2.
- Follow Section 313.0 for hanger types, spacing and load considerations (see § 1210.3). The code ties pipe support practice to Section 313.0 rather than restating all hanger spacings in Chapter 12.
Exceptions & special cases
- The code explicitly requires flexible connectors or offsets only for connections less than 2½ inches (64 mm) to heating/cooling coils, humidifiers and similar equipment — use one of the two permitted means (flexible connector OR three 90° offsets placed close to the connection) to comply. § 1210.2.
- Equipment that is part of the piping system may require additional support beyond normal pipe hangers; follow the manufacturer’s installation instructions as required by § 1210.3.
If you need to apply a different support spacing or a unique hanger design because of unusual loads, seismic considerations, or unusual thermal movement, the code directs use of Section 313.0 and other applicable sections to justify and document the approach. § 1210.3.
Common mistakes
- Rigidly fastening a run near equipment without the required flexible connector or offsets (violates § 1210.2).
- Assuming “supported” means fully restrained — the code requires supports that allow expansion/contraction between anchors, not ones that create undue stresses (§ 1210.2, § 1210.3).
- Forgetting to provide additional structural support for piping-mounted equipment (pumps, heat exchangers, circulators) as required by § 1210.3 and the manufacturer’s instructions.
- For radiant systems, failing to keep ≥ 1/4 in (6.4 mm) between adjacent plates (creates binding and stress) — check § 1210.3.
Worked example — concrete scenario
Scenario: You have a 1‑1/4 inch (nominal) hydronic supply line feeding a unit heating coil. The coil connection is less than 2½ inches (64 mm) diameter.
What the code requires and how you comply:
- Because the connection is less than 2½ in (64 mm), you must provide either a flexible connector at the coil inlet or install three 90° offsets immediately adjacent to the connection. Choose one method and install it so the coil is not subjected to thermal thrust — this follows § 1210.2.
- Support the run per Section 313.0 (as required by § 1210.3) and add structural support for the coil and any piping-mounted equipment to prevent transferred loads to the piping. Document the manufacturer’s recommended support points and provide the additional supports.
- Do not install rigid anchors so close to the coil connection that the flexible connector or offsets cannot move — the intent in § 1210.2 is to allow the thermal movement to be relieved between anchors.
Related provisions (CMC)
- § 1211.0 Joints and Connections — applies to approved joint types and installation rules.
- § 1209.0 Expansion Tanks — sizing and installation of expansion tanks affect how thermal movement and pressures are handled.
- § 1210.4 Oxygen Diffusion Corrosion — materials selection for closed hydronic systems (affects support/installation choices).
- Section 313.0 Hangers and Supports — referenced by § 1210.3 as the place to apply hanger types, spacing and load considerations.
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 6.2 High relevance — show source text
Thermal expansion and contraction forces on suspended horizontal runs of PEX tubing that can experience a 22 ºC (40ºF) or greater change in temperature (operating temperature compared to ambient temperature) shall be controlled by a means of mitigating temperature-induced stresses to other parts of the water distribution system. Means for controlling thermal expansion and contraction include
(a) loops; (b) offsets; (c) arms with rigid anchor points; and (d) supporting the tubing with continuous runs of CTS support channels with (i) rigid anchor points installed every 20 m (65 ft); and (ii) proper strapping (e.g., 27 kg (60 lb) straps or equivalent) spaced 1 m (3 ft) and rated for the maximum temperature and UV exposure of the PEX tubing application. 6.2 Vertical Tubing Runs
Thermal expansion and contraction forces on vertical runs of PEX tubing that pass through more than one floor and can experience a 22 ºC (40ºF) or greater change in temperature (operating temperature compared to ambient temperature) shall be controlled by installing
(a) a riser clamp at the top of every other floor; and (b) mid-story guides to maintain the alignment of the vertical tubing. Note: Installing riser clamps isolates expansion and contraction to two-floor intervals allowing the PEX tubing to naturally compensate for the expan- sion and contraction.
6.3 Clearance
Adequate clearance shall be provided between PEX tubing and the building structure (e.g., using bored holes and sleeves) to allow for free longitudinal movement of the tubing.
6.4 Expansion Arms and Expansion Loops
6.4.1 Expansion Arms (See Figure 1)
6.4.1.1 Expansion arms shall be installed as illustrated in Figure 1.
6.4.1.2 The minimum length of expansion arms shall be calculated using the following equation:
LB = C × √ (D × Δ L)
where
LB = length of flexible arm
C = material constant (12 for PEX)
D = nominal outside diameter of tubing
Δ L = thermal expansion length
2025 CALIFORNIA PLUMBING CODE 457
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IS 31
6.4.2 Expansion Loops (See Figure 2) 6.4.2.1 Expansion loops shall be installed at the mid-point between anchors, as illustrated in Figure 2. 6.4.2.2 The minimum length of expansion loops shall be calculated using the equation in Section 6.4.1.2; however, the distance LB shall be divided into three sections, as illustrated in Figure 2.
where
L1 = LB ÷ 5; and L2 = L1 × 2.
7 Hangers and Supports 7.1 Vertical Tubing
Vertical PEX tubing shall
(a) be supported at each floor or as specified by the water-distribution system designer to allow for expansion and contraction; and (b) have mid-story guides. 7.2 Horizontal Tubing
Unless otherwise authorized by the authority having jurisdiction, suspended horizontal runs of PEX tubing
CMC § 6.4 High relevance — show source text
6.4 Expansion Arms and Expansion Loops
6.4.1 Expansion Arms (See Figure 1)
6.4.1.1 Expansion arms shall be installed as illustrated in Figure 1.
6.4.1.2 The minimum length of expansion arms shall be calculated using the following equation:
LB = C × √ (D × Δ L)
where
LB = length of flexible arm
C = material constant (12 for PEX)
D = nominal outside diameter of tubing
Δ L = thermal expansion length
2025 CALIFORNIA PLUMBING CODE 457
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IS 31
6.4.2 Expansion Loops (See Figure 2) 6.4.2.1 Expansion loops shall be installed at the mid-point between anchors, as illustrated in Figure 2. 6.4.2.2 The minimum length of expansion loops shall be calculated using the equation in Section 6.4.1.2; however, the distance LB shall be divided into three sections, as illustrated in Figure 2.
where
L1 = LB ÷ 5; and L2 = L1 × 2.
7 Hangers and Supports 7.1 Vertical Tubing
Vertical PEX tubing shall
(a) be supported at each floor or as specified by the water-distribution system designer to allow for expansion and contraction; and (b) have mid-story guides. 7.2 Horizontal Tubing
Unless otherwise authorized by the authority having jurisdiction, suspended horizontal runs of PEX tubing
(a) NTS-1 and smaller shall be supported every 0.8 m (32 in), unless continuously supported by metallic CTS or V channels that (i) are supported at intervals not exceeding 1.8 m (6 ft); (ii) have a maximum cantilever, measured from the support to the end of the CTS support channel, of 0.5 m (1.5 ft); and (b) NTS-1-1/4 and larger shall be supported every 1.2 m (4 ft), unless continuously supported by metallic CTS or V channels that (i) are supported at intervals not exceeding 2.4 m (8 ft); and (ii) have a maximum cantilever, measured from the support to the end of the CTS support channel, of 0.5 m (1.5 ft). 7.3 Anchors
Anchors shall be
(a) used to restrict PEX tubing movement; (b) made of materials that provide rigidity to the support system and utilize pipe clamps designed for plastic tubing capable of restraining the tubing; and (c) installed in accordance with Figures 1 or 2, as applicable (i.e., anchor distances and size of arms and offsets). Note: Anchors are typically installed every 20 m (65 ft). See Section 6.
8 Joints and Connections
8.1 Assembly Procedure
The procedure for making joints shall be as specified by the manufacturer.
8.2 Concealed Joints
PEX tubing systems manufactured in accordance with the applicable standards referenced in Section 2 are deemed manufactured joints and may be installed in concealed spaces without the need for access panels.
9 Clearances
CMC § 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]
CMC § 1215.0 High relevance — show source text
HYDRONIC SPACE HEATING . . . . . . . . . . . . . . . . . 1215.0
HYDRONICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 12
Auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . 1220.0
Appliances and equipment . . . . . . . . . . . . . . . . . 1207.0
Boilers . . . . . . . . . . . . . . . . . . 1207.2, 1207.2.1, 1207.2.2
Circulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1208.0
Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1221.7
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210.0
Embedded piping and joints . . . . . . . . . . . . . . . . 1221.2
Expansion tanks . . . . . . . . . . . . . . . . . . . . . . . . . 1209.0
Hangers and supports. . . . . . . . . . . . . . . . . . . . . 1210.3
Heat emitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201.7
Heat pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.5
Heat sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203.1
Heat transfer fluid . . . . . . . . . . . . . . . . . . 1201.3, 1204.7
Identification of piping . . . . . . . . . . . . . . . . . . . . . 1204.0
Installation . . . . . . . . . . . . . . . . . . . . . . . 1205.0, 1221.0
Insulation. . . . . . . . . 1201.2, 1217.8.2, 1217.10, 1220.4.7
Joints and connections . . . . . . . . . . . . . . . . . . . . 1211.0
Materials . . . . . . . . . . . . . . . . . . . . 1210.0, Table 1210.1
Protection of potable water supply . . . . . . . . . . . 1202.0
Radiant heating and cooling . . . . . . . . . . . . . . . . 1217.0
Snow melt systems . . . . . . . . . . . . . . . . 1220.4, 1220.0,
1217.8.2, Table 1220.4.2
CMC § 43.147 High relevance — show source text
- Section 43.147 of the 1979 edition of the Uniform Building Code Standards provides: “A restrained condition in fire tests, as used in this standard, is one in which expansion at the supports of a load-carrying element resulting from the effects of the fire is resisted by forces external to the element. An unrestrained condition is one in which the load-carrying element is free to expand and rotate at its support. “Restraint in buildings is defined as follows: Floor and roof assemblies and individual beams in buildings shall be considered restrained when the surrounding or supporting structure is capable of resisting the thermal expansion throughout the range of anticipated elevated temperatures. Construction not complying . . . is assumed to be free to rotate and expand and shall be considered as unrestrained. “Restraint may be provided by the lateral stiffness of supports for floor and roof assemblies and intermediate beams forming part of the assembly. In order to develop restraint, connections must adequately transfer thermal thrusts to such supports. The rigidity of adjoining panels or structures shall be considered in assessing the capabilities of a structure to resist thermal expansion.” Because it is difficult to determine whether an existing building’s structural system is capable of providing the required restraint, the lower hourly ratings of a similar but unrestrained assembly have been recommended.
- Hourly rating based upon Table 4.2.1, Item B-12-RC-2.
TABLE 4.2.1
REINFORCED CONCRETE BEAMS—UNPROTECTED DEPTH
10″ TO LESS THAN 12″Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 ITEM
CODEDEPTH CONSTRUCTION DETAILS PERFORMANCE PERFORMANCE REFERENCE NUMBER REFERENCE NUMBER REFERENCE NUMBER NOTES REC.
HOURSITEM
CODEDEPTH CONSTRUCTION DETAILS LOAD TIME PRE- BMS-92 BMS-92 POST-BMS-92 POST-BMS-92 POST-BMS-92 B-SU-1 10″ 10″ × 41/2″ × 25 lbs “I” beam. 10 tons 39 min 7 1 1/3 For SI: 1 inch = 25.4 mm, 1 pound = 0.004448 kN, 1 ton = 8.896 kN.
Notes:
- Concentrated at mid-span.
RESOURCE A-110 2025 CALIFORNIA EXISTING BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
RESOURCE A—GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND ASSEMBLIES
CMC § 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]
CMC § 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
CMC § 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
CMC § 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.
CMC § 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]
CMC § 1208.0 Medium relevance — show source text
1208.0 Circulators and Pumps. 1208.1 General. Circulators and pumps shall be selected for their intended use based on the heat transfer fluid, intended operating temperature range and pressure. Circulators and pumps shall be installed to allow for service and maintenance. The manufacturer’s installation instructions shall be followed for correct orientation and installation. Motor operated pumps rated 600V or less shall comply with CSA C22.2 No. 108 or UL 778.
2025 CALIFORNIA MECHANICAL CODE 259
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HYDRONICS
temperature and pressure of the system and shall be compatible with the type of heat transfer fluid. Pipe fittings and valves shall be approved for the specific installation with the piping, materials to be installed and shall comply with the applicable standards referenced in Table 1210.1. Where required, exterior piping shall be protected against freezing, UV radiation, corrosion and degradation. Embedded pipe or tubing shall comply with Section 1221.2. 1210.2 Expansion and Contraction. Pipe and tubing shall be so installed that it will not be subject to undue strains or stresses, and provisions shall be made for expansion, contraction, and structural settlement. [OSHPD 1, 1R, 2, 4 & 5] Pipe connections less than 2½ inches (64 mm) to heating coils, cool- ing coils, humidifiers, and similar equipment shall have flexible connectors or three (3) 90-degree offsets in close proximity of the connection.
1210.3 Hangers and Supports. Pipe and tubing shall be supported in accordance with Section 313.0. Equipment that is part of the piping system shall be provided with additional support in accordance with this code and manufacturer’s installation instructions. Radiant systems utilizing heat emission or transfer plates shall have a gap of at least ¼ inch (6.4 mm) between adjacent plates. 1210.4 Oxygen Diffusion Corrosion. PEX and PE-RT tubing in closed hydronic systems shall contain an oxygen barrier. 1210.4.1 Vented Closed-Loop Systems. All components installed in a vented closed-loop system shall be constructed of non-ferrous or other corrosion resistant
materials.
1210.4.2 Non-Oxygen Barrier Closed-Loop Sys- tems. All components installed in a non-oxygen barrier system shall be constructed of non-ferrous or other corrosion resistant materials.
1211.0 Joints and Connections.
1211.1 General. Joints and connections shall be of an approved type. Joints shall be gas and watertight and designed for the pressure of the hydronic system. Changes in direction shall be made by the use of fittings or with pipe bends. Joints between pipe and fittings shall be installed in accordance with the manufacturer’s installation instructions. Joints used underground shall be of an approved type for buried applications in accordance with Section 1221.2.3.
1211.2 Pipe Bends. Pipe bends shall be formed in accordance with Section 1211.2.1 for PEX or Section 1211.2.2 for
PE.
CMC § 323.0 Medium relevance — show source text
54 2025 CALIFORNIA PLUMBING CODE
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GENERAL REGULATIONS
323.0 Plumbing Equipment Schedules. [OSHPD 1, 2, 3, 4 & 5] Plumbing equipment schedules shall clearly indi- cate which equipment will be on essential power or appro- priate special seismic certifications.
TABLE 313.3
HANGERS AND SUPPORTS
MATERIALS TYPES OF JOINTS HORIZONTAL VERTICAL Cast Lead and Oakum 5 feet, except 10 feet where 10 foot
lengths are installed1, 2, 3Base and each floor,
not to exceed 15 feetCast Compression Gasket Every other joint, unless over 4 feet
then support each joint1, 2, 3Base and each floor,
not to exceed 15 feetCast-Iron Hubless Shielded Coupling Every other joint, unless over 4 feet
then support each joint1,2,3,4Base and each floor,
not to exceed 15 feetCopper & Copper
AlloysSoldered, Brazed, Threaded, or
Mechanical11⁄2 inches and smaller, 6 feet;
2 inches and larger, 10 feetEach floor, not to exceed 10 feet5 Steel Pipe for Water or
DWVThreaded or Welded 3⁄4 inch and smaller, 10 feet;
1 inch and larger, 12 feetEvery other floor,
not to exceed 25 feet5Steel Pipe for Gas Threaded or Welded 1⁄2 inch, 6 feet;3⁄4 inch and 1 inch,
8 feet; 11⁄4 inches and larger, 10 feet1⁄2 inch, 6 feet;3⁄4 inch and 1 inch,
8 feet; 11⁄4 inches every floor levelSchedule 40 PVC and
ABS DWVSolvent Cemented All sizes, 4 feet; allow
for expansion every 30 feet3Base and each floor; provide
mid-story guides; provide
for expansion every 30 feetCPVC Solvent Cemented 1 inch and smaller, 3 feet;
11⁄4 inches and larger, 4 feetBase and each floor;
provide mid-story guidesCPVC-AL-CPVC Solvent Cemented 1⁄2 inch, 5 feet;3⁄4 inch, 65 inches;
1 inch, 6 feetBase and each floor;
provide mid-story guidesLead Wiped or Burned Continuous Support Not to exceed 4 feet Steel Mechanical In accordance with standards acceptable to the Authority Having Jurisdiction In accordance with standards acceptable to the Authority Having Jurisdiction PEX Cold Expansion, Insert
and Compression1 inch and smaller, 32 inches;
11⁄4 inches and larger, 4 feetBase and each floor;
provide mid-story guidesPEX-AL-PEX Metal Insert and Metal
Compression1⁄2 inch
3⁄4 inch
1 inch } All sizes 98 inchesBase and each floor;
Frequently asked questions
Do I always need a flexible connector at every equipment connection?
No. The code specifically requires flexible connectors or three 90° offsets only for pipe connections less than 2½ inches (64 mm) to heating/cooling coils, humidifiers and similar equipment (see § 1210.2). For larger connections, follow the general expansion/anchor practices in § 1210.2 and support rules in § 1210.3.
Where do I find the allowed hanger spacing and hanger types?
Chapter 12 requires support “in accordance with Section 313.0” — refer to Section 313.0 for hanger types and spacing; § 1210.3 directs you to that section.
What if the equipment manufacturer’s instructions differ from my hanger layout?
The code requires piping‑system equipment to have additional support in accordance with this code and manufacturer’s installation instructions (see § 1210.3). If there is a conflict, document manufacturer requirements and resolve with the authority having jurisdiction.
How close can I place anchors?
The code does not prescribe exact anchor spacings in § 1210.2/§ 1210.3; it requires that piping be installed so it is not subject to undue strains and that expansion/contraction be provided for. Use Section 313.0 and accepted engineering practice to set anchor spacing so thermal movement is accommodated.
Are there specific gaps required for radiant heat plates?
Yes — radiant systems using heat emission or transfer plates require a gap of at least 1/4 inch (6.4 mm) between adjacent plates as stated in § 1210.3.
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