CPC · California Plumbing Code
What are the primary and secondary roof drainage requirements?
If your roof can trap water (parapet, tall curb, etc.), the California Plumbing Code requires an emergency drainage method: either scuppers (openings at least 4 inches high) or secondary roof drains set at least 2 inches above the roof, and the primary system must be sized for a 60‑minute, 100‑year storm. Secondary drains may be separate (discharge above grade and observable) or connected into the primary downpipe downstream of the last horizontal offset — combined systems must be sized for double the local rainfall rate. Refer to **§ 1101.12**, **§ 1101.12.1**, and **§ 1101.12.2** for the detailed rules.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
The California Plumbing Code requires that roof runoff be handled by a primary roof drainage system (gutters or roof drains) sized for a 60‑minute, 100‑year storm and that secondary (emergency) roof drainage be provided where roof perimeter construction can trap water. The options for secondary drainage are scuppers/open sides or secondary roof drains (either as a separate piping system or connected in a combined system), and each option has location, sizing and discharge requirements. See § 1101.12, § 1101.12.1, and § 1101.12.2 for the governing rules.
Secondary (emergency) roof drainage must be provided when the roof perimeter can trap water; scuppers must be a minimum of 4 in. high or secondary drains must be at least 2 in. above the roof — and the systems must be sized per the CPC (§ 1101.12.2).
Requirements in detail
Primary roof drainage (what it is and how it’s sized)
- Defined: Primary roof drainage means the roof drains, gutters, vertical conductors/leaders and horizontal storm drains used to remove design storm runoff. § 1101.12.1 requires primary drainage by roof drains or gutters. § 1101.12.1 .
- Sizing basis: Primary drainage components are to be sized for a storm of 60 minutes duration with a 100‑year return period, unless the Authority Having Jurisdiction (AHJ) requires otherwise. The code points designers to local precipitation values (Table D101.1 in Appendix D) to determine rainfall intensity. § 1101.12.1 .
- Coordination: Location and sizing must be coordinated with the structural design and roof pitch (roof geometry affects both collection and allowable ponding). § 1101.12.1 .
Secondary (emergency) roof drainage — when and how
- Trigger: Secondary (emergency) roof drainage is required where roof perimeter construction extends above the roof so water can be entrapped. § 1101.12.2 .
- Methods allowed: Two methods are permitted:
- Scuppers or open-sided roof (§ 1101.12.2.1) — an open side or scupper sized to prevent ponding deeper than the roof was designed for; scupper openings must be not less than 4 inches (102 mm) high and have a width equal to the circumference of the roof drain required for the area served (sized per Table 1103.1). § 1101.12.2.1 .
- Secondary roof drains (§ 1101.12.2.2) — additional drains set not less than 2 inches (51 mm) above the roof surface; maximum riser height must prevent ponding deeper than the roof was designed for; these secondary drains must connect to an approved piping arrangement in § 1101.12.2.2.1 or § 1101.12.2.2.2. § 1101.12.2.2 .
- Secondary drain piping options:
- Separate piping system (§ 1101.12.2.2.1): Secondary drains may discharge to a piping system entirely separate from the primary roof drainage system. The discharge must be above grade in a location observable by occupants or maintenance personnel, and the secondary system shall be sized in accordance with § 1101.12.1 (i.e., same rainfall basis as the primary system). § 1101.12.2.2.1 .
- Combined system (§ 1101.12.2.2.2): Secondary drains may connect into the vertical piping of the primary storm conductor downstream of the last horizontal offset located below the roof. When combined, the system must be sized per § 1103.0 based on double the rainfall rate for the local area (i.e., designers treat the hydraulic load as twice the normal rainfall rate for sizing). § 1101.12.2.2.2 .
Decision‑relevant dimensions & values
| Requirement / threshold | Value(s) | Code Reference |
|---|---|---|
| Primary design storm | 60 minutes, 100‑year return period | § 1101.12.1 |
| Scupper minimum opening height | 4 inches (102 mm) | § 1101.12.2.1 |
| Scupper width | Width = circumference of roof drain required for area (sized per Table 1103.1) | § 1101.12.2.1 |
| Secondary roof drain elevation above roof | Not less than 2 inches (51 mm) above roof surface | § 1101.12.2.2 |
| Separate secondary discharge | Must discharge above grade at an observable location | § 1101.12.2.2.1 |
| Combined‑system sizing | Size per § 1103.0 using double the rainfall rate | § 1101.12.2.2.2 |
| Limiting ponding depth | Secondary openings/drains must prevent ponding deeper than roof design allows (use primary sizing to determine) | § 1101.12.2.1, § 1101.12.2.2 |
(Notes: actual hydraulic sizing — e.g., selection of roof drain or leader diameter and scupper width in inches of circumference — requires the rainfall intensity for your location (Table D101.1) and the sizing tables (Table 1103.1 / § 1103.0). Those tables are referenced by the CPC but were not reproduced in the retrieved sections.)
Exceptions & special cases
- AHJ authority: The CPC explicitly allows the Authority Having Jurisdiction to require different sizing or methods — “Unless otherwise required by the Authority Having Jurisdiction…” for the primary sizing basis. Designers must confirm local AHJ requirements. § 1101.12.1 .
- Choice of secondary method: Where the roof perimeter does not trap water, the secondary (emergency) drainage requirement may not apply; the code requires secondary drainage only where water would be entrapped by perimeter construction. § 1101.12.2 / § 1101.12.2.1 .
- Separate secondary discharge: If using a separate piping system, the code requires the discharge to be above grade and observable; this is often used for rooftop equipment or occupancies where visible overflow alarm is desired. § 1101.12.2.2.1 .
Common mistakes
- Installing scuppers smaller than 4 inches high or orienting them so the opening is obstructed — violates § 1101.12.2.1.
- Mounting secondary roof drains flush with, or below, the roof surface (they must be ≥ 2 inches above per § 1101.12.2.2).
- Tying secondary drains into primary piping upstream of the last horizontal offset (secondary drains must connect downstream of the last horizontal offset if combined — § 1101.12.2.2.2).
- Failing to size a combined system for double the rainfall rate, which underestimates hydraulic capacity and risks overflow. § 1101.12.2.2.2
- Omitting confirmation from the AHJ about local design storms or exceptions — the CPC allows the AHJ to require different criteria. § 1101.12.1
Worked example — concrete scenario (what you can determine from § 1101.12 series)
Scenario: A flat roof with a parapet that would trap water if primary drains fail. You must provide secondary drainage.
Steps using only the CPC text in § 1101.12 et seq.:
Recognize secondary drainage is required because the parapet can entrap water — § 1101.12.2.
Choose method — scuppers or secondary roof drains. Suppose you select scuppers (open-sided roof is not available). § 1101.12.2.1.
Minimum scupper geometry you must meet from the CPC text:
- Scupper opening height: ≥ 4 in. (102 mm). § 1101.12.2.1
- Scupper width: must equal the circumference of the roof drain required for the area served (that roof drain size is determined using Table 1103.1 and the primary storm sizing). § 1101.12.2.1
What you still need (not in § 1101.12 et seq., so you must consult the referenced items):
- The actual roof drain size (and therefore scupper width) requires the rainfall intensity for your location (Table D101.1 — 60‑min, 100‑yr intensity) and the sizing Table 1103.1 / § 1103.0. These are referenced by § 1101.12.1 and § 1101.12.2.1, but the numeric rainfall intensities and Table 1103.1 sizing numbers are not reproduced in the retrieved sections.
Alternate: If you chose a secondary roof drain instead:
- The drain riser must be not less than 2 in. above the roof surface. § 1101.12.2.2
- If you connect the secondary drains into the existing vertical primary conductor (combined), you must size the combined system per § 1103.0 for double the rainfall rate. § 1101.12.2.2.2
Summary of numeric outcomes you can set immediately from the CPC text:
- Provide scuppers ≥ 4 in. high (if scuppers chosen). § 1101.12.2.1
- Or provide secondary drains with outlets ≥ 2 in. above roof (if drains chosen). § 1101.12.2.2
- For final pipe/strainer/drain diameters, obtain local 60‑min, 100‑yr rainfall intensity (Table D101.1) and then use Table 1103.1 / § 1103.0 to compute required sizes — these steps are referenced in § 1101.12.1 and § 1101.12.2.1 but the numeric tables were not included in the retrieved excerpts.
Related provisions
- § 1101.12 — Roof Drainage; directs compliance with the subsections.
- § 1101.12.1 — Primary Roof Drainage (60‑minute, 100‑year sizing basis).
- § 1101.12.2 — Secondary Roof Drainage (methods and requirements).
- § 1101.12.2.1 — Scuppers / Open side requirements (minimum 4 in. height, width related to drain circumference).
- § 1101.12.2.2 — Secondary roof drains (minimum elevation, connection options).
- § 1101.12.2.2.1 — Separate piping system requirements (above‑grade discharge observable by occupants).
- § 1101.12.2.2.2 — Combined system connection and sizing (double rainfall rate; connect downstream of last horizontal offset).
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 1101.11 High relevance — show source text
1101.11 Paved Areas. Where the occupant creates surface water drainage, the sumps, gratings, or floor drains shall be piped to a storm drain or an approved water course. 1101.12 Roof Drainage. Roof drainage shall comply with Section 1101.12.1 and Section 1101.12.2.
1101.12.1 Primary Roof Drainage. Roof areas of a building shall be drained by roof drains or gutters. The location and sizing of drains and gutters shall be coordinated with the structural design and pitch of the roof. Unless otherwise required by the Authority Having Jurisdiction, roof drains, gutters, vertical conductors or leaders, and horizontal storm drains for primary drainage shall be sized based on a storm of 60 minutes duration and 100 year return period. Refer to Table D 101.1 (in Appendix D) for 100 years, 60-minute storms at various locations. 1101.12.2 Secondary Drainage. Secondary (emergency) roof drainage shall be provided by one of the methods specified in Section 1101.12.2.1 or Section 1101.12.2.2.
1101.12.2.1 Roof Scuppers or Open Side. Secondary roof drainage shall be provided by an opensided roof or scuppers where the roof perimeter construction extends above the roof in such a manner that water will be entrapped. An open-sided roof or scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.12.1. Scupper openings shall be not less than 4 inches (102 mm) high and have a width equal to the circumference of the roof drain required for the area served, sized in accordance with Table 1103.1.
1101.12.2.2 Secondary Roof Drain. Secondary roof drains shall be provided. The secondary roof drains shall be located not less than 2 inches (51 mm) above the roof surface. The maximum height of the roof drains shall be a height to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.12.1. The secondary roof drains shall connect to a piping system in accordance with Section 1101.12.2.2.1 or Section 1101.12.2.2.2.
1101.12.2.2.1 Separate Piping System. The secondary roof drainage system shall be a
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STORM DRAINAGE
separate system of piping, independent of the primary roof drainage system. The discharge shall be above grade, in a location observable by the building occupants or maintenance personnel. Secondary roof drain systems shall be sized in accordance with Section 1101.12.1
based on the rainfall rate for which the primary system is sized. 1101.12.2.2.2 Combined System. The secondary roof drains shall connect to the vertical piping of the primary storm drainage conductor downstream of the last horizontal offset located below the roof. The primary storm drainage system shall connect to the building storm water that connects to an underground public storm sewer. The combined secondary and primary roof drain systems shall be sized in accordance with Section 1103.0 based on double the rain fall rate for the local area.
CPC § 1101.12.2.2 High relevance — show source text
1101.12.2.2 Secondary Roof Drain. Secondary roof drains shall be provided. The secondary roof drains shall be located not less than 2 inches (51 mm) above the roof surface. The maximum height of the roof drains shall be a height to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.12.1. The secondary roof drains shall connect to a piping system in accordance with Section 1101.12.2.2.1 or Section 1101.12.2.2.2.
1101.12.2.2.1 Separate Piping System. The secondary roof drainage system shall be a
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STORM DRAINAGE
separate system of piping, independent of the primary roof drainage system. The discharge shall be above grade, in a location observable by the building occupants or maintenance personnel. Secondary roof drain systems shall be sized in accordance with Section 1101.12.1
based on the rainfall rate for which the primary system is sized. 1101.12.2.2.2 Combined System. The secondary roof drains shall connect to the vertical piping of the primary storm drainage conductor downstream of the last horizontal offset located below the roof. The primary storm drainage system shall connect to the building storm water that connects to an underground public storm sewer. The combined secondary and primary roof drain systems shall be sized in accordance with Section 1103.0 based on double the rain fall rate for the local area.
1101.13 Cleanouts. Cleanouts for building storm drains shall comply with the requirements of Section 719.0 of this code.
1101.13.1 Rain Leaders and Conductors. Rain leaders and conductors connected to a building storm sewer shall have a cleanout installed at the base of the
leader or conductor before it connects to the horizontal
drain.
1101.14 Rainwater Sumps. Rainwater sumps serving “public use” occupancy buildings shall be provided with dual pumps arranged to function alternately in the case of overload or mechanical failure. Pumps rated 600 V or less shall comply with UL 778 and shall be installed in accordance with the manufacturer’s installation instructions.
1101.15 Traps on Storm Drains and Leaders. Leaders and storm drains, where connected to a combined sewer, shall be trapped. Floor and area drains connected to a storm drain shall be trapped.
Exception: Traps shall not be required where roof drains, rain leaders, and other inlets are at locations permitted under Section 906.0, Vent Termination.
1101.15.1 Where Not Required. No trap shall be required for leaders or conductors that are connected to a sewer carrying storm water exclusively. 1101.15.2 Trap Size. Traps, where installed for individual conductors, shall be the same size as the horizontal drain to which they are connected.
1101.15.3 Method of Installation of Combined Sewer. Individual storm-water traps shall be installed on the stormwater drain branch serving each storm-water inlet, or a single trap shall be installed in the main storm drain just before its connection with the combined building sewer. Such traps shall be provided with an accessible cleanout on the outlet side of the trap.
CPC § 1103.1 High relevance — show source text
(3) Not less than two drains shall be installed in roof areas of 10 000 square feet (929 m [2] ) or less, and not less than one additional drain shall be installed for each 10 000 square feet (929 m [2] ) of roof area exceeding 10 000 square feet (929 m [2] ). (4) Each roof drain shall have a precalibrated, fixed (nonadjustable), and proportional weir (notched) in a standing water collar inside the strainer. No mechanical devices or valves shall be permitted. (5) Pipe sizing shall be based on the pre-calibrated rate of flow (gpm) (L/s) of the pre-calibrated weir for the maximum allowable water depth, and Table 1103.1 and Table 1103.2.
(6) The height of stones or other granular material above the waterproofed surface shall not be considered in water depth measurement, and the roof surface in the vicinity of the drain shall not be recessed to create a reservoir.
(7) Roof design, where controlled-flow roof drainage is used, shall be such that the design roof live load is not less than 30 lb/ft [2] (146 kg/m [2] ) to provide a safety factor exceeding the 15 lb/ft [2] (73 kg/m [2] ) represented by the depth of water stored on the roof in accordance with Table 1105.1(1). (8) Scuppers shall be provided in parapet walls. The distance of scupper bottoms above the roof level at the drains shall not exceed the maximum distances specified in Table 1105.1(2).
(9) Scupper openings shall be not less than 4 inches (102 mm) high and have a width equal to the circumference of
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STORM DRAINAGE
the roof drain required for the area served, sized in accordance with Table 1103.1.
(10)Flashings shall extend above the top of the scuppers.
(11)At a wall or parapet, 45 degree (0.79 rad) cants shall be installed.
(12)Separate storm and sanitary drainage systems shall be provided within the building.
(13)Calculations for the roof drainage system shall be submitted along with the plans to the Authority Having Jurisdiction for approval.
TABLE 1105.1(1) CONTROLLED-FLOW MAXIMUM ROOF WATER DEPTH
ROOF RISE*
(inches)MAXIMUM WATER DEPTH AT
DRAIN
(inches)
Flat3
24
45
66 For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
TABLE 1105.1(2) DISTANCE OF SCUPPER BOTTOMS ABOVE ROOF
CPC § 1103.1. High relevance — show source text
(9) Scupper openings shall be not less than 4 inches (102 mm) high and have a width equal to the circumference of
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STORM DRAINAGE
the roof drain required for the area served, sized in accordance with Table 1103.1.
(10)Flashings shall extend above the top of the scuppers.
(11)At a wall or parapet, 45 degree (0.79 rad) cants shall be installed.
(12)Separate storm and sanitary drainage systems shall be provided within the building.
(13)Calculations for the roof drainage system shall be submitted along with the plans to the Authority Having Jurisdiction for approval.
TABLE 1105.1(1) CONTROLLED-FLOW MAXIMUM ROOF WATER DEPTH
ROOF RISE*
(inches)MAXIMUM WATER DEPTH AT
DRAIN
(inches)
Flat3
24
45
66 For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
TABLE 1105.1(2) DISTANCE OF SCUPPER BOTTOMS ABOVE ROOF
ROOF RISE*
(inches)ABOVE ROOF LEVEL
AT DRAIN
(inches)
Flat3
24
45
66 For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
1105.2 Setback Roofs. Drains on setback roofs shall be permitted to be connected to the controlled-flow drainage systems provided:
(1) The setback is designed for storing water, or
(2) The square footage of the setback drainage area is converted as outlined in Section 1105.0 to gpm, and the storm-water pipe sizes in the controlled-flow system are based on the sum of the loads.
(3) The branch from each of the roof drains that are not provided with controlled flow shall be sized in accordance
with Table 1103.1.
1106.0 Engineered Storm Drainage System. 1106.1 General. The design and sizing of a storm drainage system shall be permitted to be determined by accepted engineering practices. The system shall be designed by a regis
TABLE 1105.1(1) CONTROLLED-FLOW MAXIMUM ROOF WATER DEPTH
For SI units: 1 inch = 25.4 mm
- Vertical measurement from the roof surface at the drain to the highest point of the roof surface served by the drain, ignoring a local depression immediately adjacent to the drain.
TABLE 1105.1(2) DISTANCE OF SCUPPER BOTTOMS ABOVE ROOF
For SI units: 1 inch = 25.4 mm
CPC § 1502.2 High relevance — show source text
1||||X|X|||||||||||||||||||| |1502.2||||X|X|||||||||||||||||||| |1503.3 – 1503.4|||X|||||||||||||||||||||| |1505 – 1507|||X|||||||||||||||||||||| |1507.3.10||||||||X|X|X|X|X||X|X|||||||||| |1507.7.8||||||||X|X|X|X|X||X|X|||||||||| |1509 – 1511|||X|||||||||||||||||||||| |1511.9.6||||||X|X|||||||||||||||||| |1511.10– 1511.10.1|X|||X|X|||X|X|X|X|X||X|X|||||||||| |1512|||X|||||||||||||||||||||| |1513||||||||X|X|X|X|X||X|X||||||||||
The state agency does not adopt sections identified by the following symbol:
The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
2025 CALIFORNIA BUILDING CODE 15-1
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
15-2 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
15 ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
User notes:
About this chapter: Chapter 15 provides minimum requirements for the design and construction of roof assemblies and rooftop structures. The criteria address the weather-protective barrier at the roof and, in most circumstances, a fire-resistant barrier. The chapter is largely prescriptive in nature and is based on decades of experience with various traditional materials, but it also recognizes newer products. Section 1511 addresses rooftop structures, which include penthouses, tanks, towers and spires. Rooftop penthouses larger than prescribed in this chapter must be treated as a story under Chapter 5.
ICC code development note: Code change proposals to sections preceded by the designation [BF] or [P] will be considered by one of the code development committees meeting during the 2024 (Group A) Code Development Cycle. All other code change proposals will be considered by a code development committee meeting during the 2025 (Group B) Code Development Cycle.
SECTION 1501—GENERAL
1501.1 Scope. The provisions of this chapter shall govern the design, materials, construction and quality of roof assemblies, and rooftop structures.
SECTION 1502—ROOF DRAINAGE
[P] 1502.1 General. Design and installation of roof drainage systems shall comply with this section, Section 1611 of this code and Chapter 11 of the California Plumbing Code .
[P] 1502.2 Secondary (emergency overflow) drains or scuppers. Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason. The installation and sizing of secondary emergency overflow drains, leaders and conductors shall comply with Section 1611 of this code and Chapter 11 of the California Plumbing Code .
CPC § 1101.16 Medium relevance — show source text
1101.16 Leaders, Conductors, and
Connections . . . . . . . . . . . . . . . . .207
1102.0 Roof Drains . . . . . . . . . . . . . . . . . .207
1102.1 Applications . . . . . . . . . . . . . . . . .207
1102.2 Dome Strainers Required . . . . . . .207
1102.3 Roof Drain Flashings . . . . . . . . . .207
1103.0 Size of Leaders, Conductors,
and Storm Drains . . . . . . . . . . . . .207
1103.1 Vertical Conductors and
Leaders . . . . . . . . . . . . . . . . . . . . .207
1103.2 Size of Horizontal Storm
Drains and Sewers . . . . . . . . . . . .207
1103.3 Size of Roof Gutters . . . . . . . . . . .207
1103.4 Side Walls Draining onto a Roof . . . . . . . . . . . . . . . . . .207
Table 1103.1 Sizing Roof Drains, Leaders, and Vertical Rainwater Piping . . .208
1104.0 Values for Continuous Flow . . . . .208
1104.1 General . . . . . . . . . . . . . . . . . . . . .208
1105.0 Controlled-Flow Roof
Drainage . . . . . . . . . . . . . . . . . . . .208
1105.1 Application . . . . . . . . . . . . . . . . . .208
Table 1105.1(1) Controlled-Flow Maximum Roof Water Depth . . . . . . . . . . . . .209
Table 1105.1(2) Distance of Scupper Bottoms Above Roof . . . . . . . . . . . . . . . . . .209
xxxviii 2025 CALIFORNIA PLUMBING CODE
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TABLE OF CONTENTS
1105.2 Setback Roofs . . . . . . . . . . . . . . .209
1106.0 Engineered Storm Drainage System . . . . . . . . . . . . . . . . . . . . .209
1106.1 General . . . . . . . . . . . . . . . . . . . . .209
1106.2 Siphonic Roof Drainage Systems . . . . . . . . . . . . . . . . . . . .209
1106.3 Siphonic Roof Drains . . . . . . . . . .209
1107.0 Testing . . . . . . . . . . . . . . . . . . . . .209
1107.1 Testing Required . . . . . . . . . . . . .209
1107.2 Methods of Testing Storm Drainage Systems . . . . . . . . . . . .209
Table 1103.2 Sizing of Horizontal Rainwater Piping . . . . . . . . . . . . .210
Table 1103.3 Size of Gutters . . . . . . . . . . . . . . .211
California Plumbing Code Medium relevance — show source text
|100 psf|1 hr
23 min|||7|1, 2|11/3| |F/C-4-RC-9|4″|4″ deep (4370 psi);1/4″ reinforcement bars
at 6″ pitch with3/4″ cover;1/4″ main rein-
forcement bars at 4″ pitch perpendicular
with1/2″ cover; 13′1″ span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-10|4″|4″ thick (5140 psi) deck;1/4″ reinforce-
ment bars at 71/2″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|1 hr
16 min|||7|1, 5|11/4| |F/C-4-RC-11|4″|4″ thick (4000 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom of slab; 6′6″
span restrained.|150 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-12|4″|4″ deep (2380 psi) concrete deck;
3″ × 11/2″ × 4 lbs R.S.J.; 2′6″ C.R.S.; flush
with top surface; 4″ × 6″ x 13 SWG mesh
reinforcement 1″ from bottom surface;
6′6″ span restrained.|150 psf|1 hr
3 min|||7|1, 2|1| |F/C-4-RC-13|41/2″|41/2″ thick (5200 psi) deck;1/4″ reinforce-
ment bars at 71/4″ pitch with7/8″ cover;3/8″
main reinforcement bars at 33/4″ pitch
perpendicular with1/2″ cover; 13′1″ span
restrained.|140 psf|2 hrs|||7|1, 3|2| |F/C-4-RC-14|41/2″|41/2″ deep (2525 psi) concrete deck;1/4″
reinforcement bars at 71/2″ pitch with7/8″
cover;3/8″ main reinforcement bars at
33/8″ pitch perpendicular with1/2″ cover;
13′1″ span restrained.|150 psf|42 min|||7|1, 5|2/3| |F/C-4-RC-15|41/2″|41/2″ deep (4830 psi) concrete deck;
11/2″ × No.California Plumbing Code Medium relevance — show source text
2
5
10
15
20
30|184
175
215
265
312
360
461|1168
823
806
777
750
723
670|647
533
521
501
481
461
426|229
219
269
327
379
433
541|1542
1069
1049
1017
985
955
895|852
698
684
662
638
615
574|312
296
366
440
507
570
704|1971
1346
1324
1287
1251
1216
1147|1056
863
846
821
794
768
720|454
424
524
620
702
780
937|2996
1999
1971
1927
1884
1841
1759|1545
1308
1283
1243
1205
1166
1101| |50|0
2
5
10
15
20
30|176
168
204
253
299
345
442|1292
971
953
923
894
866
809|704
613
602
583
562
543
502|220
209
257
313
363
415
521|1724
1273
1252
1217
1183
1150
1086|948
811
795
765
736
708
649|295
280
347
418
481
544
674|2223
1615
1591
1551
1512
1473
1399|1189
1007
991
963
934
906
848|428
401
496
589
668
741
892|3432
2426
2396
2347
2299
2251
2159|1818
1509
1490
1455
1421
1387
1318| |100|0
2
5CPC § 2025 Medium relevance — show source text
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
FORMAT OF THE UNIFORM PLUMBING CODE
Chapter 10 Traps and Interceptors.
Chapter 10 regulates the material, design, and installation of traps, interceptors, and separators. Traps are required on drainage type plumbing fixtures and must be self-scouring without interior partitions. Interceptors, on the other hand, are designed to control what goes down a drain. Interceptors are used to keep harmful substances from entering the sanitary drainage system, such as grease, sand, oil and other materials. The retained materials need periodic removal to maintain efficiency and function of the separating device. The capacity of an interceptor is based on retention and flow rate. There are many types of interceptors that are used at beauty salons, hospitals, meat, fish or foul packaging, refineries, repair garages, gas stations, car washing facilities, various plants, factories, and processing sites. The designer of the building is responsible for locating interceptors with the expectation for the frequency of maintenance, ease of cleaning and floor space for equipment.
Chapter 11 Storm Drainage.
Chapter 11 regulates the removal of stormwater from roofs, yards, paved areas, and similar areas. The objective of storm drainage systems is to provide a conduit or channel through which runoff will be carried from a point of collection to a point of disposal; this protects the property and the public from the uncontrolled flow of runoff and ensures that drains and inlets are adequately sized to receive the volume of runoff that flows to the drains. For the purpose of system design, it’s necessary to specify the duration of a selected storm. All methods used to determine volumes and peak flow use historical data. Drain location must be coordinated with the architectural design of the building. When selecting the type of roof drain to use, the roof construction and its thickness, along with the intended use of the roof, are required. Where the roof perimeter extends above the roof in such a manner that water is entrapped and causes ponding, or if any portion of the roof is designed so water can pond, secondary drainage is required. Where secondary drainage is required, scuppers, or a secondary system of roof drains and pipes, are installed to prevent the accumulation of excessive rainwater.
Chapter 12 Fuel Gas Piping.
Chapter 12 regulates the installation of gas piping in a building, structure or within the property lines of buildings up to 5 psi. Gas piping systems must supply the minimum volume of gas required by each gas appliance to perform their proper operation under working conditions without exceeding the maximum pressure specified by each manufacturer. Because of the hazards associated with fuel gas, it is important to ensure the gas system has been inspected and tested, and that it is safe to turn on the gas supply to the building.
Chapter 13 Health Care Facilities and Medical Gas and Medical Vacuum Systems.
Chapter 13 regulates the installation, inspection, testing, maintenance, performance, and safe practices for medical gas and vacuum systems located in health care facilities. This chapter addresses the installation and maintenance of health care fixtures, devices, and equipment. The purpose of medical gas and medical vacuum systems is to provide safe and sufficient flows at required pressures to the medical gas outlet or vacuum inlet terminals. System design and layout should allow convenient access by the medical staff to outlet and inlet terminals, valves, and equipment during patient care or emergencies, as safety is of primary concern.
Chapter 14 Firestop Protection.
CPC § 7.3 Medium relevance — show source text
OF WATER PER FOOT LENGTH OF PIPING**|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING|OUNCES OF WATER PER FOOT LENGTH OF PIPING| |NOMINAL
SIZE
(inch)|COPPER
M|COPPER
L|COPPER
K|CPVC
CTS
SDR 11|CPVC
SCH 40|PEX-AL- PEX|** PE-AL- PE**|CPVC
SCH 80|PEX CTS
SDR 9|PE-RT
SDR 9|PP
SDR 6|PP
SDR 7.3|PP
SDR 11|CPVC
PIPE
SDR 11| |3⁄8|1.06|0.97|0.84|0.68|1.17|0.59|0.59|0.85|0.64|0.64|0.85|1.02|NA|1.48| |1⁄2|1.69|1.55|1.45|1.23|1.89|1.22|1.22|1.44|1.18|1.18|1.35|1.64|NA|2.33| |3⁄4|3.43|3.22|2.90|2.52|3.38|3.28|3.28|2.72|2.35|2.35|2.14|2.54|NA|3.68| |1|5.81|5.49|5.17|4.24|5.53|5.37|5.37|4.58|3.88|3.88|3.46|4.22|NA|5.83| |11⁄4|8.70|8.36|8.09|6.38|9.66|8.65|8.65|8.23|5.80|5.80|5.47|6.59|NA|9.35| |11⁄2|12.18|11.83|11.45|8.95|13.20|13.91|13.91|11.38|8.08|8.08|8.64|10.27|NA|12.27| |2|21.50|20.58|20.04|15.38|21.88|23.16|23.16|19.11|13.86|13.86|13.64|16.42|NA|19.19|For SI units: 1 ounce = 29.573 mL, 1 inch = 25 mm, 1 foot = 304.8 mm
- NA: Not Applicable
CPC § 120.8 Medium relevance — show source text
8, 120.8(a), 120.8(d) Supply 140.4(e)1, 140.4(f)2, 170.2(c)4C, D, O Temperature 140.4(b)2, 140.4(b)3, 140.4(j), 150.0(h), 160.3(b)2, 170.2(c)2, 170.2(c)4H Ventilation 120.1(d), 120.6(c)7, 160.2(b)2A, 160.2(c)5 Wattage 120.6(c), 120.6(d)3, 120.6(j)3, 120.9(b), 140.4(k)6, 160.4(e)2, 170.2(c)4I Zone 140.4(d), 170.2(c)4B Designated Efficiency 120.1(c)1B, 150.0(m)12C, 160.2(b)1C, 160.2(c)1B Designated Solar Zone 110.10(b)1A, 110.10(b)1B Diagnostic Evaluation 140.3(a)9, 141.0(b)2Q Diagnostic Testing 10-103(a)5, 110.1(c), 120.4(g)1, 141.0(b)2D, 141.0(b)2E, 150.0(m)1, 150.0(m)11, 150.0(m)13, 150.0(o), 150.1(c)7, 150.1(c)9, 150.1(c)10, 150.2(b)1D, 150.2(b)1E, 150.2(b)1F, 150.2(b)1M, 160.2(a)1, 160.2(b)2B, 160.3(b)5, 160.3(c)2H, 170.2(c)3B, 180.1(b)3, 180.2(b)2, 180.2(b)5 Differential Pressure 140.4(k)6, 170.2(c)4I Dimming Controls 150.0(k)2, 160.5(a)2 Direct Digital Control (DDC) 110.12(b), 120.1(d), 120.2(b), 120.2(e), 120.2(i), 120.2(j), 120.2(k), 140.4(c)2, 140.4(d), 140.4(k)6, 160.3(a)2, 170.2(c)4A, B, I Direct Expansion (DX) 140.4(a), 140.4(e)2, 140.4(m), 170.2(c)4K Direct Expansion (DX) Unit Requirements for Cooling Stages and Compressor Displacement Table 140.4-H, Table 170.2-H Direct Sunlight 130.1(d), 140.3(a)6E, 140.3(d), 140.4(e)2D, 150.1(c)4, 160.5(b)4D, 170.2(a)3B, 170.2(c)4C Directional Inlets 110.4(b) Directory 110.0(b), 110.1(b), 150.
CPC § 102.0 Medium relevance — show source text
downspouts, and roof washers.|Every 6 months| |Inspect and clear debris from the roof or other aboveground rainwater collection
surface.|Every 6 months| |Remove tree branches and vegetation overhanging roof or other aboveground rain-
water collection surface.|As needed| |Inspect pumps and verify operation.|After initial installation and every 12 months thereafter| |Inspect valves and verify operation.|After initial installation and every 12 months thereafter| |Inspect pressure tanks and verify operation.|After initial installation and every 12 months thereafter| |Clear debris and inspect storage tanks, locking devices, and verify operation.|After initial installation and every 12 months thereafter| |Inspect caution labels and marking.|After initial installation and every 12 months thereafter|K 102.0 Connection.
K 102.1 General. No water piping supplied by a potable rainwater catchment system shall be connected to a source of supply without the approval of the Authority Having Jurisdiction, Health Department, or other department having jurisdiction.
K 102.2 Connections to Public or Private Potable Water Systems. Potable rainwater catchment systems shall have no direct connection to a public or private potable water supply or alternate water source system. Potable water from a public or private potable water system is permitted to be used as makeup water to the rainwater storage tank provided the public, or private potable water supply connection is protected by an air gap or reduced-pressure principle backflow preventer in accordance with this code. K 102.3 Backflow Prevention. The potable rainwater catchment system shall be protected against backflow in accordance with this code.
K 103.0 Potable Rainfall Catchment System Materials.
K 103.1 Collections Surfaces. The collection surface for potable applications shall be constructed of a hard, impervious material and shall be approved for potable water use. Roof coatings, paints, and liners shall comply with NSF Protocol P151. K 103.1.1 Prohibited. Roof paints and coatings with lead, chromium, or zinc shall not be permitted. Wood roofing material and lead flashing shall not be permitted. K 103.2 Rainwater Catchment System Drainage Materials. Materials used in rainwater catchment drainage systems, including gutters, downspouts, conductors, and leaders shall be in accordance with the requirements of this code for storm drainage.
K 103.3 Storage Tanks. Rainwater storage shall comply with Section K 105.0.
K 103.4 Water Supply and Distribution Materials. Potable rainwater supply and distribution materials shall comply with the requirements of this code for potable water supply and distribution systems.
K 104.0 Design and Installation.
K 104.1 Collection Surfaces. Rainwater shall be collected from a roof or other cleanable aboveground surfaces specifically designed for rainwater catchment. A rainwater catchment system shall not collect rainwater from:
(1) Vehicular parking surfaces
(2) Surface water runoff
(3) Bodies of standing water
K 104.2 Prohibited Discharges. Overflows, condensate, and bleed-off pipes from roof-mounted equipment and appliances shall not discharge onto roof surfaces that are intended to collect rainwater.
Frequently asked questions
Do I always need secondary drainage on a roof with a parapet?
Yes — where the roof perimeter construction extends above the roof so water can be entrapped, secondary (emergency) roof drainage is required under § 1101.12.2.
How high must a secondary roof drain be above the roof surface?
A secondary roof drain must be located not less than 2 inches (51 mm) above the roof surface per § 1101.12.2.2.
How big must a scupper opening be?
Scupper openings must be not less than 4 inches (102 mm) high and the width must equal the circumference of the roof drain required for the area served (sized per Table 1103.1) — see § 1101.12.2.1.
Can I tie secondary drains into the primary downspout?
Yes — but only if you connect the secondary drains to the vertical piping of the primary storm conductor downstream of the last horizontal offset located below the roof and size the combined system per § 1103.0 for double the rainfall rate (see § 1101.12.2.2.2).
If I use a separate secondary piping system, where must it discharge?
A separate secondary system must discharge above grade at a location observable by building occupants or maintenance personnel, and be sized in accordance with § 1101.12.1 (the same rainfall basis as the primary system). § 1101.12.2.2.1
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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