CRC · California Residential Code

When are automatic sprinkler systems required in dwellings?

If you’re building or remodeling a townhouse or a one‑ or two‑family home in California, the California Residential Code (CRC) requires an automatic sprinkler system (see **§ R309.1** and **§ R309.2**) unless a specific exception applies (small detached ADUs meeting the ADU exception, alterations to unsprinklered existing units, or limited small spaces like tiny closets and small bathrooms). Design must follow **§ R309** or **NFPA 13D**, sprinklers must be listed residential sprinklers with correct temperature ratings, and limited backflow exceptions apply when criteria in **§ R309.3.1.1** are met.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

An automatic sprinkler system is required in townhouses (bold) under § R309.1 and in one‑ and two‑family dwellings under § R309.2 of the California Residential Code. Systems must be designed and installed in accordance with § R309 or NFPA 13D as allowed by § R309.1.1, § R309.2.1, and § R309.3.1. The CRC further defines required sprinkler locations, allowable exceptions for specific small spaces, and installation rules (temperature ratings, listed residential sprinklers, and backflow provisions) in § R309.3.

The single most important rule: if the dwelling is a townhouse or a one‑ or two‑family dwelling, an automatic sprinkler system is required unless one of the narrow exceptions in § R309.2 or § R309.3.1.2 applies.

Requirements in detail

Scope — which dwellings

Townhouses: An automatic sprinkler system shall be installed in townhouses (§ R309.1) (Exception only for alterations/additions to existing townhouses that do not have sprinklers).
One‑ and two‑family dwellings: An automatic sprinkler system shall be installed in one‑ and two‑family dwellings (§ R309.2). Exceptions apply for some additions/alterations and limited accessory dwelling units (ADUs).

Design and installation standard

Sprinkler systems shall be designed and installed in accordance with § R309 or NFPA 13D (see § R309.1.1, § R309.2.1, § R309.3.1). Section R309.3 is considered equivalent to NFPA 13D for purposes of the CRC.

Required locations and allowable omissions

Sprinklers shall be installed to protect all areas of a dwelling unit (general rule in § R309.3.1.2). The code then lists limited exceptions (attics, certain small closets, small bathrooms, garages, etc.).
Backflow: A backflow preventer is not required to separate a sprinkler system from the domestic water distribution if conditions in § R309.3.1.1 are met (compliance with NFPA 13D or § R309, potable piping materials, and no antifreeze or fire department connection).
Sprinkler type and temperature rating: Sprinklers must be listed residential sprinklers and meet temperature rating limits (generally 135°F–225°F; intermediate rating 175°F–225°F for certain locations) per § R309.3.2 and § R309.3.2.1/2.

Quick decision table

Decision dimension	Value / Threshold	Code Reference
Townhouse — sprinkler required?	Yes (required)	§ R309.1
One‑ and two‑family dwellings — sprinkler required?	Yes (required)	§ R309.2
ADU exemption (detached accessory dwelling unit)	≤ 1,200 sq ft and primary residence without sprinklers and same lot	§ R309.2 (Exceptions)
Attics, crawl spaces, normally unoccupied concealed spaces	Not required unless they contain fuel‑fired appliances (then sprinklers only above the equipment)	§ R309.3.1.2 (Exception 1)
Clothes/linen/pantry closet exemption	≤ 24 sq ft and smallest dimension ≤ 3 ft, with gypsum board walls/ceiling	§ R309.3.1.2 (Exception 2)
Bathroom exemption	≤ 55 sq ft	§ R309.3.1.2 (Exception 3)
Garage / carport / exterior porches	Not required	§ R309.3.1.2 (Exception 4)
Backflow preventer required?	Not required if criteria in § R309.3.1.1 are met (no antifreeze, potable piping, compliance with NFPA 13D or § R309)	§ R309.3.1.1
Sprinkler temperature ratings	135°F–225°F (general); 175°F–225°F intermediate for specified locations	§ R309.3.2 / R309.3.2.1/2

Exceptions & special cases

Alterations/additions: An automatic sprinkler system is not required for additions or alterations to existing townhouses or one‑ and two‑family dwellings if the existing building did not have sprinklers (Exceptions in § R309.1 and § R309.2).
Accessory Dwelling Units (detached ADUs): A detached ADU may be exempt from the dwelling sprinkler requirement if it satisfies all ADU exception criteria listed in § R309.2 (including the 1,200 sq ft size limit and being on the same lot as the unsprinklered primary residence).
Small spaces: The code allows omission of sprinklers in specific small/limited spaces (attics without fuel‑fired appliances; closets ≤ 24 sq ft and ≤ 3 ft smallest dimension; bathrooms ≤ 55 sq ft; garages/carports/exterior porches), per § R309.3.1.2.
Backflow and water system configuration: If the system is installed per NFPA 13D or § R309 and does not use antifreeze or a fire‑department connection, a backflow preventer is not required to separate the sprinkler piping from the potable water distribution (§ R309.3.1.1).

Common mistakes

Assuming all accessory units are exempt — not true; the ADU exemption has specific requirements including the 1,200 sq ft limit and same‑lot condition (§ R309.2).
Omitting sprinklers in attics regardless of fuel equipment — attic omission only applies if no fuel‑fired appliances are present; otherwise a sprinkler is required above the equipment (§ R309.3.1.2 (Exception 1)).
Installing non‑listed or wrong‑temperature sprinklers — the CRC requires listed residential sprinklers and temperature rating compliance per § R309.3.2 and § R309.3.2.1/2.
Requiring backflow preventer when not required — if the conditions of § R309.3.1.1 are met, a backflow preventer to separate systems is not required; but if antifreeze or an FDC is used then backflow/other separations may apply.

Worked example — concrete scenario

Scenario: New detached single‑family house, 2,800 sq ft, with an attached garage and a detached accessory dwelling unit of 1,000 sq ft on the same lot. The primary residence has no existing sprinklers.

Apply the rules:

Primary detached one‑family dwelling (2,800 sq ft): Sprinklers required under § R309.2; system to be designed to § R309 or NFPA 13D (see § R309.2.1).
Attached garage: Sprinklers not required in the garage per the exceptions in § R309.3.1.2 (Exception 4), but the dwelling itself requires full protection in habitable areas.
Detached ADU (1,000 sq ft): Because the ADU is ≤ 1,200 sq ft, on the same lot, and the existing primary residence does not have sprinklers, the ADU may be exempt from having its own automatic sprinkler system per the ADU exception in § R309.2. Confirm all listed exception conditions are met.
Backflow: If the sprinkler for the main dwelling is designed per NFPA 13D or § R309, using potable‑rated piping and no antifreeze or FDC, a backflow preventer to separate the system is not required per § R309.3.1.1. Confirm installer and AHJ acceptance.

Related provisions

§ R309.1 — Townhouse sprinkler requirement (design per § R309 or NFPA 13D).
§ R309.2 — One‑ and two‑family dwelling sprinkler requirement and ADU exception.
§ R309.3 / § R309.3.1 / § R309.3.1.2 — Dwelling unit sprinkler design, required locations, and exceptions for small spaces.
§ R309.3.1.1 — Backflow protection exceptions when system meets enumerated conditions.
§ R309.3.2 / § R309.3.2.1 / § R309.3.2.2 — Sprinkler listing, temperature ratings, and intermediate temperature requirements.
Related California Fire/Building Code: NFPA 13D allowance and supervision/monitoring exceptions for one‑ and two‑family dwellings under the Fire Code (see California Fire Code § 903.3.1.3 and supervision exceptions).

Code references

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

CRC § 2.1 High relevance — show source text
R307.2 Construction. Storm shelters shall be constructed in accordance with this code and ICC 500.

R307.2.1 Sealed documentation. The construction documents for all structural components and impact protective systems installed in storm shelters shall be prepared and sealed by a registered design professional indicating compliance with ICC 500.

Exception: Storm shelters, structural components and impact-protective systems that are listed and labeled to indicate compliance with ICC 500.

SECTION R308—SITE ADDRESS

R308.1 Address identification. Buildings shall be provided with approved address identification. The address identification shall be legible and placed in a position that is visible from the street or road fronting the property. Address identification characters shall contrast with their background. Address numbers shall be Arabic numbers or alphabetical letters. Numbers shall not be spelled out. Each character shall be not less than 4 inches (102 mm) in height with a stroke width of not less than 0.5 inch (12.7 mm). Where

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required by the fire code official, address identification shall be provided in additional approved locations to facilitate emergency response. Where access is by means of a private road and the building address cannot be viewed from the public way, a monument, pole or other sign or means shall be used to identify the structure. Address identification shall be maintained.

SECTION R309—AUTOMATIC SPRINKLER SYSTEMS

R309.1 Townhouse automatic sprinkler systems. An automatic sprinkler system shall be installed in townhouses.

Exception: An automatic sprinkler system shall not be required where additions or alterations are made to existing townhouses that do not have an automatic sprinkler system installed.

R309.1.1 Design and installation. Automatic sprinkler systems for townhouses shall be designed and installed in accordance with Section R309 or NFPA 13D.

R309.2 One- and two-family dwellings automatic sprinkler systems. An automatic sprinkler system shall be installed in one- and two-family dwellings.

Exceptions:
1. An automatic sprinkler system shall not be required for additions or alterations to existing buildings that are not already provided with a sprinkler system. 2. Accessory Dwelling Unit, provided that all of the following are met: 2.1. The unit meets the definition of an Accessory Dwelling Unit as defined in the Government Code Section 65852.2. 2.2. The existing primary residence does not have automatic fire sprinklers. 2.3. The accessory detached dwelling unit does not exceed 1,200 square feet in size. 2.4. The unit is on the same lot as the primary residence.
R309.2.1 Design and installation. Automatic sprinkler systems shall be designed and installed in accordance with Section R309 or NFPA 13D.

R309.3 Dwelling unit automatic sprinkler systems.
CRC § 1.1 High relevance — show source text
SECTION R309—AUTOMATIC SPRINKLER SYSTEMS

R309.1 Townhouse automatic sprinkler systems. An automatic sprinkler system shall be installed in townhouses.

Exception: An automatic sprinkler system shall not be required where additions or alterations are made to existing townhouses that do not have an automatic sprinkler system installed.

R309.1.1 Design and installation. Automatic sprinkler systems for townhouses shall be designed and installed in accordance with Section R309 or NFPA 13D.

R309.2 One- and two-family dwellings automatic sprinkler systems. An automatic sprinkler system shall be installed in one- and two-family dwellings.

Exceptions:
1. An automatic sprinkler system shall not be required for additions or alterations to existing buildings that are not already provided with a sprinkler system. 2. Accessory Dwelling Unit, provided that all of the following are met: 2.1. The unit meets the definition of an Accessory Dwelling Unit as defined in the Government Code Section 65852.2. 2.2. The existing primary residence does not have automatic fire sprinklers. 2.3. The accessory detached dwelling unit does not exceed 1,200 square feet in size. 2.4. The unit is on the same lot as the primary residence.
R309.2.1 Design and installation. Automatic sprinkler systems shall be designed and installed in accordance with Section R309 or NFPA 13D.

R309.3 Dwelling unit automatic sprinkler systems.

R309.3.1 General. The design and installation of automatic sprinkler systems shall be in accordance with NFPA 13D or Section R309.3, which shall be considered to be equivalent to NFPA 13D. Partial automatic sprinkler systems shall be permitted to be installed only in buildings not required to be equipped with an automatic sprinkler system. Section R309.3 shall apply to standalone and multipurpose wet-pipe sprinkler systems that do not include the use of antifreeze. A multipurpose automatic sprinkler system shall provide domestic water to both fire sprinklers and plumbing fixtures. A stand-alone automatic sprinkler system shall be separate and independent from the water distribution system.

R309.3.1.1 Backflow protection. A backflow preventer shall not be required to separate a sprinkler system from the water distri- bution system, provided that: 1. The system complies with NFPA 13D or Section R309; 2. Piping materials are suitable for potable water in accordance with the California Plumbing Code; and 3. The system does not contain antifreeze or have a fire department connection.

R309.3.1.2 Required sprinkler locations. Sprinklers shall be installed to protect all areas of a dwelling unit.
CRC § 2.1 High relevance — show source text
R309.2.1 Design and installation. Automatic sprinkler systems shall be designed and installed in accordance with Section R309 or NFPA 13D.

R309.3 Dwelling unit automatic sprinkler systems.

R309.3.1 General. The design and installation of automatic sprinkler systems shall be in accordance with NFPA 13D or Section R309.3, which shall be considered to be equivalent to NFPA 13D. Partial automatic sprinkler systems shall be permitted to be installed only in buildings not required to be equipped with an automatic sprinkler system. Section R309.3 shall apply to standalone and multipurpose wet-pipe sprinkler systems that do not include the use of antifreeze. A multipurpose automatic sprinkler system shall provide domestic water to both fire sprinklers and plumbing fixtures. A stand-alone automatic sprinkler system shall be separate and independent from the water distribution system.

R309.3.1.1 Backflow protection. A backflow preventer shall not be required to separate a sprinkler system from the water distri- bution system, provided that: 1. The system complies with NFPA 13D or Section R309; 2. Piping materials are suitable for potable water in accordance with the California Plumbing Code; and 3. The system does not contain antifreeze or have a fire department connection.

R309.3.1.2 Required sprinkler locations. Sprinklers shall be installed to protect all areas of a dwelling unit.

Exceptions:
1. Attics, crawl spaces and normally unoccupied concealed spaces that do not contain fuel-fired appliances do not require sprinklers. In attics, crawl spaces and normally unoccupied concealed spaces that contain fuel-fired equipment, a sprinkler shall be installed above the equipment; however, sprinklers shall not be required in the remainder of the space.
2. Clothes closets, linen closets and pantries not exceeding 24 square feet (2.2 m [2] ) in area, with the smallest dimension not greater than 3 feet (915 mm) and having wall and ceiling surfaces of gypsum board.
3. Bathrooms not more than 55 square feet (5.1 m [2] ) in area.
4. Garages; carports; exterior porches; unheated entry areas, such as mud rooms, that are adjacent to an exterior door; and similar areas.
R309.3.2 Sprinklers. Sprinklers shall be new listed residential sprinklers and shall be installed in accordance with the sprinkler manufacturer’s instructions.

R309.3.2.1 Temperature rating and separation from heat sources. Except as provided for in Section R309.3.2, sprinklers shall have a temperature rating of not less than 135°F (57°C) and not more than 225°F (107°C). Sprinklers shall be separated from heat sources as required by the sprinkler manufacturer’s installation instructions.

R309.3.2.2 Intermediate temperature sprinklers. Sprinklers shall have an intermediate temperature rating not less than 175°F (79°C) and not more than 225°F (107°C) where installed in the following locations:
1. Directly under skylights, where the sprinkler is exposed to direct sunlight.
2. In attics.
3. In concealed spaces located directly beneath a roof.
4. Within the distance to a heat source as specified in Table R309.3.2.2 .
CRC § 903.4 Medium relevance — show source text
903.4 Sprinkler system supervision and alarms. Automatic sprinkler system supervision and alarms shall comply with Sections 903.4.1 through 903.4.3.

903.4.1 Electronic supervision. Valves controlling the water supply for automatic sprinkler systems, pumps, tanks, water levels and temperatures, critical air pressures and waterflow switches on all automatic sprinkler systems shall be electrically supervised by a listed fire alarm control unit.

Exceptions:
1. Automatic sprinkler systems protecting one- and two-family dwellings.
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1. Limited area sprinkler systems in accordance with Section 903.3.8, provided that backflow prevention device test valves located in limited area sprinkler system supply piping shall be locked in the open position unless supplying an occupancy required to be equipped with a fire alarm system, in which case the backflow preventer valves shall be electrically supervised by a tamper switch installed in accordance with NFPA 72 and separately annunciated.
2. Automatic sprinkler systems installed in accordance with NFPA 13R where a common supply main is used to supply both domestic water and the automatic sprinkler system, and a separate shutoff valve for the automatic sprinkler system is not provided.
3. Jockey pump control valves that are sealed or locked in the open position.
4. Control valves to commercial kitchen hoods, paint spray booths or dip tanks that are sealed or locked in the open position.
5. Valves controlling the fuel supply to fire pump engines that are sealed or locked in the open position.
6. Trim valves to pressure switches in dry, preaction and deluge sprinkler systems that are sealed or locked in the open position.
7. Underground key or hub gate valves in roadway boxes.
903.4.2 Monitoring. Alarm, supervisory and trouble signals shall be distinctly different and shall be automatically transmitted to an approved supervising station or, where approved by the fire code official, shall sound an audible signal at a constantly attended location.

903.4.3 Alarms. An approved audible and visual sprinkler waterflow alarm device, located on the exterior of the building in an approved location, shall be connected to each automatic sprinkler system. Such sprinkler waterflow alarm devices shall be activated by water flow equivalent to the flow of a single sprinkler of the smallest orifice size installed in the system. Where a waterflow switch is required by Section 903.4.1 to be electrically supervised, such sprinkler waterflow alarm devices shall be powered by a fire alarm control unit or, where provided, a fire alarm system. Where a fire alarm system is provided, actuation of the automatic sprinkler system shall actuate the building fire alarm system.

Exception: Automatic sprinkler systems protecting one- and two-family dwellings.

903.5 Inspection, testing and maintenance. Automatic sprinkler systems shall be inspected, tested and maintained in accordance with Section 901.

903.6 Where required in existing buildings and structures. An automatic sprinkler system shall be provided in existing buildings and structures where required in Chapter 11.

SECTION 904—ALTERNATIVE AUTOMATIC FIRE-EXTINGUISHING SYSTEMS

904.1 General. Automatic fire-extinguishing systems, other than automatic sprinkler systems, shall be designed, installed, inspected, tested and maintained in accordance with the provisions of this section and the applicable referenced standards.
CRC § 901.1 Medium relevance — show source text
9 FIRE PROTECTION AND LIFE SAFETY SYSTEMS

User notes:

About this chapter: Chapter 9 prescribes the minimum requirements for active fire protection equipment systems to perform the functions of detecting a fire, alerting the occupants or fire department of a fire emergency, mass notification, gas detection, controlling smoke and controlling or extinguishing the fire. Generally, the requirements are based on the occupancy, the height and the area of the building, because these are the factors that most affect firefighting capabilities and the relative hazard of a specific building or portion thereof. This chapter parallels and is substantially duplicated in Chapter 9 of the California Fire Code.

SECTION 901—GENERAL

901.1 Scope. The provisions of this chapter shall specify where fire protection and life safety systems are required and shall apply to the design, installation and operation of fire protection and life safety systems.

901.2 Fire protection systems. Fire protection and life safety systems shall be installed, repaired, operated and maintained in accordance with this code and the California Fire Code .

Any fire protection or life safety system for which an exception or reduction to the provisions of this code has been granted shall be considered to be a required system.

Exception: Any fire protection or life safety system or portion thereof not required by this code shall be permitted to be installed for partial or complete protection provided that such system meets the requirements of this code.

901.3 Modifications. Persons shall not remove or modify any fire protection system installed or maintained under the provisions of this code or the California Fire Code without approval by the building official.

901.4 Threads. Threads provided for fire department connections to automatic sprinkler systems, standpipes, yard hydrants or any other fire hose connection shall be compatible with the connections used by the local fire department.

901.5 Administration of installation acceptance tests. Fire protection systems shall be tested in accordance with the requirements of this code and the California Fire Code . Where required, the tests shall be conducted in the presence of the building official. Tests required by this code, the California Fire Code and the standards listed in this code shall be conducted at the expense of the owner or the owner’s authorized agent. It shall be unlawful to occupy portions of a structure until the required fire protection systems within that portion of the structure have been tested and approved.

901.6 Supervisory service. Where required, fire protection systems shall be monitored by an approved supervising station in accordance with NFPA 72.

901.6.1 Automatic sprinkler systems. Automatic sprinkler systems shall be monitored by an approved supervising station.

Exceptions:
1. A supervising station is not required for automatic sprinkler systems protecting one- and two-family dwellings.
2. Limited area systems in accordance with Section 903.3.8.
901.6.2 Fire alarm systems. Fire alarm systems required by the provisions of Section 907.2 of this code and Sections 907.2 and 907.9 of the California Fire Code shall be monitored by an approved supervising station in accordance with Section 907.6.6 of this code.

Exceptions:
1. Single- and multiple-station smoke alarms required by Section 907.2.11.
2. Smoke detectors in Group I-3 occupancies.
3. Supervisory service is not required for automatic sprinkler systems in one- and two-family dwellings.
901.6.3 Group H. Supervision and monitoring of emergency alarm, detection and automatic fire-extinguishing systems in Group H occupancies shall be in accordance with the California Fire Code .
CRC § 2-5 Medium relevance — show source text
Part II—Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

CHAPTER 2 DEFINITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

R201 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

R202 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Part III—Building Planning and Construction . . . . . . . . . . . .3-5

CHAPTER 3 BUILDING PLANNING . . . . . . . . . . . . . . . . . . . . .3-5

R300 Site Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

R301 Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

R302 Fire-Resistant Construction . . . . . . . . . . . . . . . . . . . . 3-23

R303 Foam Plastic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31

R304 Protection of Wood and Wood-Based Products

Against Decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-33

R305 Protection Against Subterranean Termites. . . . . . . 3-35

R306 Flood-Resistant Construction. . . . . . . . . . . . . . . . . . . 3-36

R307 Storm Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40

R308 Site Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40

R309 Automatic Sprinkler Systems . . . . . . . . . . . . . . . . . . . 3-41

R310 Smoke Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-54

R311 Carbon Monoxide Alarms. . . . . . . . . . . . . . . . . . . . . . . 3-58

R312 Minimum Room Areas . . . . . . . . . . . . . . . . . . . . . . . . . 3-59

R313 Ceiling Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-59
CRC § 3.2. Medium relevance — show source text
Provide automatic sprinkler system protection. 3.2. Construct the attic using noncombustible materials. 3.3. Construct the attic using fire-retardant-treated wood complying with Section 2303.2 of the California Building Code .

3.4. Fill the attic with noncombustible insulation.

The height of the roof assembly shall be determined by measuring the distance from the lowest required fire vehicle access road surface adjacent to the building to the eave of the highest pitched roof, the intersection of the highest roof to the exterior wall, or the top of the highest parapet, whichever yields the greatest distance. For the purpose of this measurement, required fire vehicle access roads shall include only those roads that are necessary for compliance with Section 503. 4. Group R-4, Condition 2 occupancy attics not required by Item 1 to have sprinklers shall comply with one of the following: 4.1. Provide automatic sprinkler system protection. 4.2. Provide a heat detection system throughout the attic that is arranged to activate the building fire alarm system. 4.3. Construct the attic using noncombustible materials. 4.4. Construct the attic using fire-retardant-treated wood complying with Section 2303.2 of the California Building Code .

4.5. Fill the attic with noncombustible insulation.

903.3.1.3 NFPA 13D sprinkler systems. Automatic sprinkler systems installed in one- and two-family dwellings; Group R-3; Group R-4, Condition 1; and townhouses shall be permitted to be installed throughout in accordance with NFPA 13D as amended in Chapter 80.

903.3.2 Quick-response and residential sprinklers. Where automatic sprinkler systems are required by this code, quickresponse or residential automatic sprinklers shall be installed in all of the following areas in accordance with Section 903.3.1 and their listings:
1. Throughout all spaces within a smoke compartment containing care recipient sleeping units in Group I-2 in accordance with the California Building Code .
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1. Reserved.
2. Throughout all spaces within a smoke compartment containing treatment rooms in ambulatory care facilities.
3. Dwelling units and sleeping units in Group I-1 and R occupancies.
4. Light-hazard occupancies as defined in NFPA 13.
903.3.3 Obstructed locations. Automatic sprinklers shall be installed with regard to obstructions that will delay activation or obstruct the water distribution pattern and shall be in accordance with the applicable automatic sprinkler system standard that is being used. Automatic sprinklers shall be installed in or under covered kiosks, displays, booths, concession stands or equipment that exceeds 4 feet (1219 mm) in width. Not less than a 3-foot (914 mm) clearance shall be maintained between automatic sprinklers and the top of piles of combustible fibers.

Exception: Kitchen equipment under exhaust hoods protected with a fire-extinguishing system in accordance with Section 904.

903.3.4 Actuation. Automatic sprinkler systems shall be automatically actuated unless specifically provided for in this code.
CRC § 1.1.3 Medium relevance — show source text
1.1.3 Scope. The provisions of this code shall apply to the construction, alteration, movement, enlargement, replacement, repair, equip- ment, use and occupancy, location, maintenance, removal and demolition of every detached one- and two-family dwelling and townhouse not more than three stories above grade plane in height with a separate means of egress and structures accessory thereto throughout the State of California.

Exceptions: 1. Live/work units complying with the requirements of Section 508.5 of the California Building Code shall be permitted to be constructed as one- and two-family dwellings or townhouses in accordance with this code, as applicable. Fire suppression required by Section 508.5.7 of the California Building Code when constructed under the California Residential Code for one- and two-family dwellings shall conform to Section 903.3.1.3 of the California Building Code. 2. Owner-occupied lodging houses with five or fewer guestrooms shall be permitted to be constructed in accordance with the California Residential Code for one- and two-family dwellings when equipped with a fire sprinkler system in accordance with Section R309.

1.1.3.1 Classification. Structures or portions of structures shall be classified with respect to occupancy in one or more of the groups listed in Chapter 3 of the California Building Code. A room or space that is intended to be occupied at different times for different purposes shall comply with all of the requirements that are applicable to each of the purposes for which the room or space will be occupied. Structures with multiple occupancies or uses shall comply with Section 508 of the California Building Code. Where a struc- ture is proposed for a purpose that is not specifically provided for in this code, such structure shall be classified in the group that the occupancy most nearly resembles, according to the fire safety and relative hazard involved in accordance with this code or the Cali- fornia Building Code.

Note: Live/work units complying with the requirements of Section 508.5 of the California Building Code are classified as a Group R-2 occupancy and are permitted to be constructed as one- and two-family dwellings or townhouses in accordance with this code.

1.1.3.1.1 Utility and Miscellaneous Group U. Buildings and structures of an accessory character and miscellaneous structures not classified in any specific occupancy shall be constructed, equipped and maintained to conform to the requirements of this code commensurate with the fire and life hazard incidental to their occupancy. Group U shall include, but not be limited to, the following:

Agricultural buildings

Aircraft hangars, accessory to a one- or two-family residence (see Section 412.5 of the California Building Code)

Barns

Carports

Fences more than 7 feet (2134 mm) high

Grain silos, accessory to a residential occupancy

Greenhouses

Livestock shelters

Private garages

Retaining walls

Sheds

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Stables

Tanks

Towers
CRC § 1.5.2 Medium relevance — show source text
1.5.2_||||X|||||||||||||||||||| |R109.1.5.3||||X|||||||||||||||||||| |R109.1.6|||X|X|||||||||||||||||||| |R109.1.6.1||||X|||||||||||||||||||| |R109.1.6.2||||X|||||||||||||||||||| |R109.2 - R109.4|||X||||||||||||||||||||| |R110 - R110.4|||X||||||||||||||||||||| |R111 - R111.3|||X||||||||||||||||||||| |R113.1 - R113.2|||X||||||||||||||||||||| |R114.1 - R114.4|||X|||||||||||||||||||||

The state agency does not adopt sections identified with the following symbol: †

1-2 2025 CALIFORNIA RESIDENTIAL CODE

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

PART I—ADMINISTRATIVE

1 ADMINISTRATION

DIVISION I CALIFORNIA ADMINISTRATION

SECTION 1.1—GENERAL

1.1.1 Title. These regulations shall be known as the California Residential Code, may be cited as such and will be referred to herein as “this code.” The California Residential Code is Part 2.5 of thirteen parts of the official compilation and publication of the adoption, amendment and repeal of building regulations to the California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This part incorporates by adoption the 2024 International Residential Code of the International Code Council with necessary California amendments.

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

1.1.3 Scope. The provisions of this code shall apply to the construction, alteration, movement, enlargement, replacement, repair, equip- ment, use and occupancy, location, maintenance, removal and demolition of every detached one- and two-family dwelling and townhouse not more than three stories above grade plane in height with a separate means of egress and structures accessory thereto throughout the State of California.

Exceptions: 1. Live/work units complying with the requirements of Section 508.5 of the California Building Code shall be permitted to be constructed as one- and two-family dwellings or townhouses in accordance with this code, as applicable. Fire suppression required by Section 508.5.7 of the California Building Code when constructed under the California Residential Code for one- and two-family dwellings shall conform to Section 903.3.1.3 of the California Building Code. 2. Owner-occupied lodging houses with five or fewer guestrooms shall be permitted to be constructed in accordance with the California Residential Code for one- and two-family dwellings when equipped with a fire sprinkler system in accordance with Section R309.

1.1.3.1 Classification. Structures or portions of structures shall be classified with respect to occupancy in one or more of the groups _listed in Chapter 3 of the California Building Code.
CRC § 3-33 Medium relevance — show source text
R304 Protection of Wood and Wood-Based Products

Against Decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-33

R305 Protection Against Subterranean Termites. . . . . . . 3-35

R306 Flood-Resistant Construction. . . . . . . . . . . . . . . . . . . 3-36

R307 Storm Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40

R308 Site Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-40

R309 Automatic Sprinkler Systems . . . . . . . . . . . . . . . . . . . 3-41

R310 Smoke Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-54

R311 Carbon Monoxide Alarms. . . . . . . . . . . . . . . . . . . . . . . 3-58

R312 Minimum Room Areas . . . . . . . . . . . . . . . . . . . . . . . . . 3-59

R313 Ceiling Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-59

R314 Mezzanines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-60

R315 Sleeping Lofts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-60

R316 Habitable Attics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-61

R317 Garages and Carports. . . . . . . . . . . . . . . . . . . . . . . . . . 3-61

R318 Means of Egress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-62

R319 Emergency Escape and Rescue Openings . . . . . . . . 3-65

R320 Handrails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-67

R321 Guards and Window Fall Protection . . . . . . . . . . . . . 3-67

R322 Accessibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-68

R323 Elevators and Platform Lifts . . . . . . . . . . . . . . . . . . . . 3-68

R324 Glazing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-68
CRC § 901.6 Medium relevance — show source text
901.6 Supervisory service. Where required, fire protection systems shall be monitored by an approved supervising station in accordance with NFPA 72.

901.6.1 Automatic sprinkler systems. Automatic sprinkler systems shall be monitored by an approved supervising station.

Exceptions:
1. A supervising station is not required for automatic sprinkler systems protecting one- and two-family dwellings.
2. Limited area systems in accordance with Section 903.3.8.
901.6.2 Fire alarm systems. Fire alarm systems required by the provisions of Section 907.2 of this code and Sections 907.2 and 907.9 of the California Fire Code shall be monitored by an approved supervising station in accordance with Section 907.6.6 of this code.

Exceptions:
1. Single- and multiple-station smoke alarms required by Section 907.2.11.
2. Smoke detectors in Group I-3 occupancies.
3. Supervisory service is not required for automatic sprinkler systems in one- and two-family dwellings.
901.6.3 Group H. Supervision and monitoring of emergency alarm, detection and automatic fire-extinguishing systems in Group H occupancies shall be in accordance with the California Fire Code .

901.7 Fire areas. Where buildings, or portions thereof, are divided into fire areas so as not to exceed the limits established for requiring a fire protection system in accordance with this chapter, such fire areas shall be separated by fire walls constructed in accordance with Section 706, fire barriers constructed in accordance with Section 707, or horizontal assemblies constructed in accordance with Section 711, or a combination thereof having a fire-resistance rating of not less than that determined in accordance with Section 707.3.10.

SECTION 902—FIRE PUMP AND RISER ROOM SIZE

[F] 902.1 Pump and riser room size. Where provided, fire pump rooms and automatic sprinkler system riser rooms shall be designed with adequate space for all equipment necessary for the installation, as defined by the manufacturer, with sufficient working room around the stationary equipment. Clearances around equipment to elements of permanent construction, including other installed equipment and appliances, shall be sufficient to allow inspection, service, repair or replacement without removing such elements of permanent construction or disabling the function of a required fire-resistance-rated assembly. Fire pump and automatic sprinkler system riser rooms shall be provided with doors and unobstructed passageways large enough to allow removal of the largest piece of equipment.

2025 CALIFORNIA BUILDING CODE 9-7

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

FIRE PROTECTION AND LIFE SAFETY SYSTEMS

[F] 902.1.1 Access. Automatic sprinkler system risers, fire pumps and controllers shall be provided with ready access. Where located in a fire pump room or automatic sprinkler system riser room, the door shall be permitted to be locked provided that the key is available at all times.

[F] 902.1.2 Marking on access doors. Access doors for automatic sprinkler system riser rooms and fire pump rooms shall be labeled with an approved sign. The lettering shall be in contrasting color to the background. Letters shall have a minimum height of 2 inches (51 mm) with a minimum stroke of [3] / 8 inch (10 mm).
CRC § 903.4 Medium relevance — show source text
[A] 903.4 Sprinkler system supervision and alarms. Automatic sprinkler system supervision and alarms shall comply with Sections 903.4.1 through 903.4.3.

[F] 903.4.1 Electronic supervision. Valves controlling the water supply for automatic sprinkler systems, pumps, tanks, water levels and temperatures, critical air pressures and waterflow switches on all automatic sprinkler systems shall be electrically supervised by a listed fire alarm control unit.

Exceptions:
1. Automatic sprinkler systems protecting one- and two-family dwellings.
2. Limited area sprinkler systems in accordance with Section 903.3.8, provided that backflow prevention device test valves located in limited area sprinkler system supply piping shall be locked in the open position unless supplying an occupancy required to be equipped with a fire alarm system, in which case the backflow preventer valves shall be electrically supervised by a tamper switch installed in accordance with NFPA 72 and separately annunciated.
3. Automatic sprinkler systems installed in accordance with NFPA 13R where a common supply main is used to supply both domestic water and the automatic sprinkler system, and a separate shutoff valve for the automatic sprinkler system is not provided.
4. Jockey pump control valves that are sealed or locked in the open position.
5. Control valves to commercial kitchen hoods, paint spray booths or dip tanks that are sealed or locked in the open position.
6. Valves controlling the fuel supply to fire pump engines that are sealed or locked in the open position.
7. Trim valves to pressure switches in dry, preaction and deluge sprinkler systems that are sealed or locked in the open position.
8. Underground key or hub gate valves in roadway boxes.
[F] 903.4.2 Monitoring. Alarm, supervisory and trouble signals shall be distinctly different and shall be automatically transmitted to an approved supervising station or, where approved by the fire code official, shall sound an audible signal at a constantly attended location.

[F] 903.4.3 Alarms. An approved audible and visual sprinkler waterflow alarm device, located on the exterior of the building in an approved location, shall be connected to each automatic sprinkler system. Such sprinkler waterflow alarm devices shall be activated by water flow equivalent to the flow of a single sprinkler of the smallest orifice size installed in the system. Where a waterflow switch is required by Section 903.4.1 to be electrically supervised, such sprinkler waterflow alarm devices shall be powered by a fire alarm control unit or, where provided, a fire alarm system. Where a fire alarm system is provided, actuation of the automatic sprinkler system shall actuate the building fire alarm system.

Exception: Automatic sprinkler systems protecting one- and two-family dwellings.

[F] 903.5 Inspection, testing and maintenance. Automatic sprinkler systems shall be inspected, tested and maintained in accordance with the California Fire Code .

SECTION 904—ALTERNATIVE AUTOMATIC FIRE-EXTINGUISHING SYSTEMS

[F] 904.1 General. Automatic fire-extinguishing systems, other than automatic sprinkler systems, shall be designed, installed, inspected, tested and maintained in accordance with the provisions of this section and the applicable referenced standards.

[F] 904.2 Where permitted. Automatic fire-extinguishing systems installed as an alternative to the required automatic sprinkler systems of Section 903 shall be approved by the fire code official.

Frequently asked questions

Do townhouses always need sprinklers, even for small remodels?

No — townhouses are required to have sprinklers per § R309.1, but the code provides an exception: an automatic sprinkler system is not required where additions or alterations are made to existing townhouses that do not already have sprinklers.

Can a detached ADU be built without a sprinkler system?

Yes, a detached ADU can be exempt only if it meets all criteria in the ADU exception to § R309.2, including being ≤ 1,200 sq ft, located on the same lot, and the primary residence lacking sprinklers.

Are attics covered by the sprinkler requirement?

Attics are generally exempt from sprinklers only if they are normally unoccupied and contain no fuel‑fired appliances. If fuel‑fired equipment is present, a sprinkler is required above that equipment per § R309.3.1.2 (Exception 1).

Do I need a backflow preventer between the sprinkler and domestic water?

Not automatically. § R309.3.1.1 says a backflow preventer is not required if the system complies with NFPA 13D or § R309, uses potable‑rated piping, and contains no antifreeze or fire‑department connection.

What kind of sprinklers must be used?

The CRC requires listed residential sprinklers and sets temperature rating ranges (typical 135°F–225°F, with intermediate ratings 175°F–225°F for certain exposures) under § R309.3.2 and related subsections.

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