CHBC · California Historical Building Code
How can fire‑resistive construction requirements be met or modified for historic buildings?
Under the CHBC, qualified historic buildings can often avoid expensive one‑hour fire‑resistive upgrades by installing approved automatic sprinkler systems (designed for exposure protection), providing an approved life‑safety evaluation, or other enforcing‑agency‑approved measures; historic glazing and original wood doors can be retained where smoke seals and sprinklers protect the area (see § 8‑402.1, § 8‑402.2, § 8‑402.3) .
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
The California Historical Building Code allows alternatives to prescriptive fire‑resistive construction for qualified historical buildings. Principal relief is provided where an automatic sprinkler system or other approved alternatives can be used in place of upgrading exterior walls, interior one‑hour construction, or replacing historical glazing and doors — see § 8-402.1, § 8-402.2, and § 8-402.3 . These options are subject to approval by the local enforcing agency and must achieve a level of life‑safety acceptable under the CHBC .
The single most important rule: where the CHBC allows it, an approved automatic sprinkler system can substitute for many required fire‑resistive upgrades in historic buildings (see § 8-402.1, § 8-402.2, § 8-402.3) .
Requirements in detail
Key defined terms (first mention bolded)
- Qualified historical building — building designated as historical under the CHBC (see Chapter 8‑1 definitions) .
- Automatic sprinkler system — the sprinkler option referenced in the CHBC; when used it must be designed and installed as required elsewhere in the CHBC (see § 8-410) .
- One‑hour fire‑resistive construction — the common code threshold that the CHBC may waive or modify for historic buildings under conditions in § 8-402.2 .
- Enforcing agency — the local or state authority that approves alternatives under the CHBC (see administration provisions) .
What each controlling section allows and requires
§ 8-402.1 — Exterior wall construction: Instead of bringing existing exterior walls and opening protection to the regular code fire‑resistance level, the requirement may be satisfied by installing an automatic sprinkler system designed for exposure protection. The CHBC explicitly permits sprinklers to be installed on the exterior, requires at least one sprinkler located over each opening required to be protected, and requires additional sprinkler distribution along combustible walls under roof lines that fail to meet fire‑resistive requirements relative to property lines. Sprinkler systems may be tied to the domestic water supply on the supply‑main side of the building shut‑off valve; a shut‑off valve may be installed provided it is locked in the open position § 8-402.1 .
§ 8-402.2 — One‑hour construction: An existing qualified historical building is not required to be upgraded to one‑hour fire‑resistive construction (including one‑hour corridors) if one of the following is provided: (1) an automatic sprinkler system throughout, (2) an approved life safety evaluation, or (3) other alternative measures approved by the enforcing agency. The section removes the mandatory upgrade when one of these alternatives is accepted § 8-402.2 .
§ 8-402.3 — Openings in fire‑rated systems: Historical glazing materials and solid wood unrated doors used in interior walls that would otherwise require a one‑hour fire rating may be approved where (a) operable windows and doors in the affected area are provided with appropriate smoke seals, and (b) the area is provided with an automatic sprinkler system. This provides a pathway to retain original historic doors/glazing when combined with smoke sealing and sprinklers § 8-402.3 .
Decision table — when to use each CHBC option
| Decision dimension | Trigger / Value | Acceptable CHBC alternative | Code Reference |
|---|---|---|---|
| Exterior walls or openings do not meet regular code exposure requirements | Existing historic exterior walls / openings | Install an automatic sprinkler system designed for exposure protection; exterior sprinklers allowed; ≥1 sprinkler over each protected opening; sprinklers distributed along combustible walls under roof lines | § 8-402.1 |
| Requirement to upgrade to one‑hour construction (walls/corridors) | Any construction or occupancy | Not required if one of: (1) automatic sprinkler system throughout, (2) approved life safety evaluation, (3) other measures approved by enforcing agency | § 8-402.2 |
| Interior one‑hour fire‑rated wall contains historic glazing / solid wood unrated doors | Original historic glazing or solid wood doors that are unrated | Permit retained glazing/doors if operable windows/doors have smoke seals and area is sprinklered | § 8-402.3 |
Exceptions & special cases
- The CHBC specifically permits exterior sprinklers to be connected to the domestic water supply on the supply‑main side of the building shut‑off valve and allows a shut‑off valve only if it is locked open — do not install a shut‑off you intend to use regularly unless approved § 8-402.1 .
- One‑hour construction upgrades are optional when the alternatives in § 8-402.2 are accepted; however acceptance of a life safety evaluation or other measures requires approval by the enforcing agency — these are case‑by‑case and may require documentation and justification § 8-402.2 .
- Retaining historical glazing or solid wood unrated doors is conditional on both smoke sealing and sprinkler protection of the area; neither alone is sufficient under § 8-402.3 .
Common mistakes
- Assuming the CHBC is a blanket exemption: it is not. The CHBC provides alternative compliance options, but those alternatives must be implemented and approved by the enforcing agency (see § 8-402.2) .
- Installing exterior sprinklers without following the “over openings” requirement: the CHBC requires at least one sprinkler over each opening required to be protected; omitting this can lead to a denial of the substitution under § 8-402.1 .
- Using a shut‑off valve for the sprinkler system that is not locked open — the CHBC permits a shut‑off only if it is locked in the open position § 8-402.1 .
- Expecting historic glazing/doors to be automatically acceptable — they must be paired with appropriate smoke seals and sprinklers per § 8-402.3 .
- Relying on the sprinkler option without consulting Section § 8-410 for sprinkler requirements (the CHBC cross‑references automatic sprinkler standards) — check § 8-410 for system standards and NFPA references .
Worked example — concrete scenario
Scenario: A two‑story, 8,000 ft² qualified historical commercial building has original wood‑frame exterior walls with historic windows. Under the regular code the exterior walls and openings adjacent to property lines would require upgraded fire‑resistive construction.
CHBC application:
- Owner proposes an automatic sprinkler system designed for exposure protection with sprinklers placed on the exterior, ensuring at least one sprinkler over each historic window or opening that would otherwise need protection. Additional heads are placed along combustible walls under roof lines where exposures exist. The system connection is tied to the domestic water supply on the supply‑main side of the building shut‑off valve; the valve is locked open. This directly follows the allowance in § 8-402.1 and provides the enforcing agency the substitution rather than requiring wall upgrades .
- Because the owner is providing the sprinkler system throughout the building, the CHBC indicates the owner is not required to upgrade corridors and walls to one‑hour fire‑resistive construction (per § 8-402.2) — the sprinkler system satisfies that alternative path .
- The building retains historical single‑pane glazing and solid wood interior doors. The owner installs smoke seals on operable windows and doors in affected areas and confirms sprinkler coverage in those areas. Under § 8-402.3, the enforcing agency may approve retention of the historic glazing and doors when these measures are in place .
Note: the enforcing agency may still require documentation, design details (sprinkler design per § 8-410), or a life safety evaluation; obtain written approval before proceeding .
Related provisions (CHBC)
- § 8-410 — Automatic sprinkler system standards and NFPA cross‑references (required when CHBC requires sprinklers) .
- § 8-401.1 — CHBC purpose and requirement to accept reasonably equivalent alternatives to the regular code (basis for these substitutions) .
- § 8-302.3 — Occupancy separations reductions/omissions when sprinklers are provided throughout (related occupancy relief) .
- § 8-404 — Wood lath and plaster fire rating guidance (relevant when interior finishes are historic) .
- CHBC administration and enforcement chapters (e.g., § 8-103) for approval, appeals and enforcing‑agency authority .
Code references
Grounded in the retrieved California Historical Building Code — click a citation to read the verbatim passage:
CHBC § 8-402 High relevance — show source text
SECTION 8-402 — FIRE-RESISTIVE CONSTRUCTION
8-402.1 Exterior wall construction. The fire-resistance requirement for existing exterior walls and existing opening protection may be satisfied when an automatic sprinkler system designed for exposure protection is installed per the CHBC. The automatic sprinklers may be installed on the exterior with at least one sprinkler located over each opening required to be protected. Additional sprinklers shall also be distributed along combustible walls under the roof lines that do not meet the fire-resistive requirement due to relationship to property lines as required by regular code. Such sprinkler systems may be connected to the domestic water supply on the supply-main side of the building shut-off valve. A shut-off valve may be installed for the sprinkler system, provided it is locked in an open position.
8-402.2 One-hour construction. Upgrading an existing qualified historical building or property to one-hour fire-resistive construction and one-hour fire-resistive corridors shall not be required regardless of construction or occupancy when one of the following is provided:
- An automatic sprinkler system throughout. See Section 8-410 for automatic sprinkler systems.
- An approved life safety evaluation.
- Other alternative measures as approved by the enforcing agency.
8-402.3 Openings in fire-rated systems. Historical glazing materials and solid wood unrated doors in interior walls required to have one-hour fire rating may be approved when operable windows and doors are provided with appropriate smoke seals and when the area affected is provided with an automatic sprinkler system. See Section 8-410 for automatic sprinkler systems.
SECTION 8-403 — INTERIOR FINISH MATERIALS
New non-historical interior wall and ceiling finishes shall conform to the provisions of the regular code. Existing non-conforming materials used in interior walls and finishes may be surfaced with an approved fire-retardant to increase the rating of the natural finish to within reasonable proximity of the required rating. For wood lath and plaster walls, see Section 8-404.
Exception: When an automatic sprinkler system is provided throughout the building, existing finishes shall be approved.
SECTION 8-404 — WOOD LATH AND PLASTER
Wood lath and plaster walls may be considered in accordance with codes, standards and listings published prior to 1943 whereby a wood stud wall assembly with gypsum or lime plaster on hand split or sawn wooden lath obtains a one-half-hour fire-resistive rating. This rating may be increased for interior walls to as much as one hour by filling the wall with mineral fiber or glass fiber.
SECTION 8-405 — OCCUPANCY SEPARATION
See Chapter 8-3.
SECTION 8-406 — MAXIMUM FLOOR AREA
See Chapter 8-3.
SECTION 8-407 — VERTICAL SHAFTS
Vertical shafts need not be enclosed when such shafts are blocked at every floor level by the installation of not less than 2 full inches (51 mm) of solid wood or equivalent construction to prevent the initial passage of smoke and flame. Automatic sprinkler systems or other solutions may be considered on a case-by-case basis, in lieu of enclosure of vertical shafts and stairwells.
SECTION 8-408 — ROOF COVERING
Existing or original roofing materials may be repaired or reconstructed subject to the following requirements:
- The original or historical roofing system shall be detailed or modified as necessary in order to be capable of providing shelter while preserving the historical materials and appearance of the roof.
CHBC § 8-302.3 High relevance — show source text
8-302.3 Occupancy separations. Required occupancy separations of more than one hour may be reduced to one-hour fire-resistive construction with all openings protected by not less than three-fourths-hour fire-resistive assemblies of the self-closing or automatic-closing type when the building is provided with an automatic sprinkler system throughout the entire building in accordance with Section 8-410.2. Doors equipped with automatic-closing devices shall be of a type which will function upon activation of a device which responds to products of combustion other than heat.
Required occupancy separations of one hour may be omitted when the building is provided with an automatic sprinkler system throughout.
8-302.4 Maximum floor area. Regardless of the use or character of occupancy, the area of a one-story qualified historical building or property may have, but shall not exceed, a floor area of 15,000 square feet (1393.5 m [2] ) unless such an increase is otherwise permitted in regular code. Multistory qualified historical buildings (including basements and cellars) shall be in accordance with regular code requirements.
Exception: Historical buildings may be unlimited in floor area without fire-resistive area separation walls:
- When provided with an automatic sprinkler, or
- Residential occupancies of two stories or less when provided with a complete fire alarm and annunciation system and where the exiting system conforms to regular code.
8-302.5 Maximum height. The maximum height and number of stories of a qualified historical building or property shall not be limited because of construction type, provided such height or number of stories does not exceed that of its historical design.
8-302.5.1 High-rise buildings. Occupancies B, F-1, F-2 or S in high-rise buildings with floors located more than 75 feet above the lowest floor level having building access may be permitted with only the stories over 75 feet provided with an automatic fire sprinkler system if:
- The building construction type and the exits conform to regular code, and
- A complete building fire alarm and annunciation system is installed, and
- A fire barrier is provided between the sprinklered and nonsprinklered floors.
8-302.6 Fire-resistive construction. See Chapter 8-4.
8-302.7 Light and ventilation. Existing provisions for light and ventilation which do not, in the opinion of the enforcing agency, constitute a safety hazard may remain. See Section 8-303.6 for residential requirements. See Section 8-503 for Escape or Rescue Windows and Doors.
SECTION 8-303 — RESIDENTIAL OCCUPANCIES
8-303.1 Purpose. The purpose of this section is to provide regulations for those buildings designated as qualified historical buildings or properties and classified as residential occupancies. The CHBC requires enforcing agencies to accept any reasonably equivalent alternative to the regular code when dealing with qualified historical buildings and properties.
8-303.2 Intent. The intent of the CHBC is to preserve the integrity of qualified historical buildings and properties while maintaining a reasonable degree of protection of life, health and safety for the occupants.
8-303.3 Application and scope. The provisions of this section shall apply to all qualified historical buildings used for human habitation. Those dwelling units intended only for display, or public use with no residential use involved, need not comply with the requirements of this section.
8-303.4 Fire escapes. See Chapter 8-5.
2025 CALIFORNIA HISTORICAL BUILDING CODE 5
CHBC § 8-303.6 High relevance — show source text
8-303.6 Light and ventilation. Windows in habitable rooms shall have an area of 6 percent of the floor area, or 6 square feet (0.56 m [2] ), whichever is greater. Windows in sleeping rooms shall be openable (see Section 8-503). Residential occupancies need not be provided with electrical lighting.
8-303.7 Alteration and repair. The alteration and repair of qualified historical buildings or properties may permit the replacement, retention and extension of original materials and the continued use of original methods of construction, provided a life safety hazard is not created or continued. Alterations and repairs shall be consistent with the CHBC.
The amount of alterations and repairs is not limited, provided there is no nonhistorical increase in floor area, volume or size of the building or property.
8-303.8 Exiting. See Chapter 8-5.
6 2025 CALIFORNIA HISTORICAL BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
8-4 FIRE PROTECTION
SECTION 8-401 — PURPOSE, INTENT AND SCOPE
8-401.1 Purpose. The purpose of this chapter is to provide regulations for fire protection of qualified historical buildings or properties. The CHBC requires enforcing agencies to accept any reasonably equivalent alternatives to the regular code when dealing with qualified historical buildings or properties.
8-401.2 Intent. The intent of the CHBC is to preserve the integrity of qualified historical buildings or properties while maintaining a reasonable degree of fire protection based primarily on the life safety of the occupants and firefighting personnel.
8-401.3 Scope. This chapter shall apply when required by the provisions of Section 8-102.
SECTION 8-402 — FIRE-RESISTIVE CONSTRUCTION
8-402.1 Exterior wall construction. The fire-resistance requirement for existing exterior walls and existing opening protection may be satisfied when an automatic sprinkler system designed for exposure protection is installed per the CHBC. The automatic sprinklers may be installed on the exterior with at least one sprinkler located over each opening required to be protected. Additional sprinklers shall also be distributed along combustible walls under the roof lines that do not meet the fire-resistive requirement due to relationship to property lines as required by regular code. Such sprinkler systems may be connected to the domestic water supply on the supply-main side of the building shut-off valve. A shut-off valve may be installed for the sprinkler system, provided it is locked in an open position.
8-402.2 One-hour construction. Upgrading an existing qualified historical building or property to one-hour fire-resistive construction and one-hour fire-resistive corridors shall not be required regardless of construction or occupancy when one of the following is provided:
- An automatic sprinkler system throughout. See Section 8-410 for automatic sprinkler systems.
- An approved life safety evaluation.
- Other alternative measures as approved by the enforcing agency.
8-402.3 Openings in fire-rated systems. Historical glazing materials and solid wood unrated doors in interior walls required to have one-hour fire rating may be approved when operable windows and doors are provided with appropriate smoke seals and when the area affected is provided with an automatic sprinkler system. See Section 8-410 for automatic sprinkler systems.
SECTION 8-403 — INTERIOR FINISH MATERIALS
CHBC § 8-3 High relevance — show source text
TREATMENT. An act of work to carry out preservation, restoration, stabilization, rehabilitation or reconstruction.
4 2025 CALIFORNIA HISTORICAL BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
8-3 USE AND OCCUPANCY
SECTION 8-301 — PURPOSE AND SCOPE
8-301.1 Purpose. The purpose of the CHBC is to provide regulations for the determination of occupancy classifications and conditions of use for qualified historical buildings or properties.
8-301.2 Scope. Every qualified historical building or property for which a permit or approval has been requested shall be classified prior to permit issuance according to its use or the character of its occupancy in accordance with the regular code and applicable provisions of this chapter.
SECTION 8-302 — GENERAL
8-302.1 Existing use. The use or character of occupancy of a qualified historical building or property, or portion thereof, shall be permitted to continue in use regardless of any period of time in which it may have remained unoccupied or in other uses, provided such building or property otherwise conforms to all applicable requirements of the CHBC.
8-302.2 Change in occupancy. The use or character of the occupancy of a qualified historical building or property may be changed from or returned to its historical use or character, provided the qualified historical building or property conforms to the requirements applicable to the new use or character of occupancy as set forth in the CHBC. Such change in occupancy shall not mandate conformance with new construction requirements as set forth in regular code.
8-302.3 Occupancy separations. Required occupancy separations of more than one hour may be reduced to one-hour fire-resistive construction with all openings protected by not less than three-fourths-hour fire-resistive assemblies of the self-closing or automatic-closing type when the building is provided with an automatic sprinkler system throughout the entire building in accordance with Section 8-410.2. Doors equipped with automatic-closing devices shall be of a type which will function upon activation of a device which responds to products of combustion other than heat.
Required occupancy separations of one hour may be omitted when the building is provided with an automatic sprinkler system throughout.
8-302.4 Maximum floor area. Regardless of the use or character of occupancy, the area of a one-story qualified historical building or property may have, but shall not exceed, a floor area of 15,000 square feet (1393.5 m [2] ) unless such an increase is otherwise permitted in regular code. Multistory qualified historical buildings (including basements and cellars) shall be in accordance with regular code requirements.
Exception: Historical buildings may be unlimited in floor area without fire-resistive area separation walls:
- When provided with an automatic sprinkler, or
- Residential occupancies of two stories or less when provided with a complete fire alarm and annunciation system and where the exiting system conforms to regular code.
8-302.5 Maximum height. The maximum height and number of stories of a qualified historical building or property shall not be limited because of construction type, provided such height or number of stories does not exceed that of its historical design.
CHBC § 8-801 High relevance — show source text
SECTION 8-801 — PURPOSE, INTENT AND SCOPE
8-801.1 Purpose. The purpose of the CHBC is to provide regulations for the use of historical methods and materials of construction that are at variance with regular code requirements or are not otherwise codified, in buildings or structures designated as qualified historical buildings or properties. The CHBC require enforcing agencies to accept any reasonably equivalent alternatives to the regular code when dealing with qualified historical buildings or properties.
8-801.2 Intent. It is the intent of the CHBC to provide for the use of historical methods and materials of construction that are at variance with specific code requirements or are not otherwise codified.
8-801.3 Scope. Any construction type or material that is, or was, part of the historical fabric of a structure is covered by this chapter. Archaic materials and methods of construction present in a historical structure may remain or be reinstalled or be installed with new materials of the same class to match existing conditions.
SECTION 8-802 — GENERAL ENGINEERING APPROACHES
Strength values for archaic materials shall be assigned based upon similar conventional codified materials, or on tests as hereinafter indicated. The archaic materials and methods of construction shall be thoroughly investigated for their details of construction in accordance with Section 8-703. Testing shall be performed when applicable to evaluate existing conditions. The architect or structural engineer in responsible charge of the project shall assign allowable stresses or strength levels to archaic materials. Such assigned strength values shall not be greater than those provided for in the following sections without adequate testing, and shall be subject to the concurrence of the enforcing agency.
SECTION 8-803 — NONSTRUCTURAL ARCHAIC MATERIALS
Where nonstructural historical materials exist in uses which do not meet the requirements of the regular code, their continued use is allowed by this code, provided that any public health and life safety hazards are mitigated subject to the concurrence of the enforcing agency.
SECTION 8-804 — ALLOWABLE CONDITIONS FOR SPECIFIC MATERIALS
Archaic materials which exist and are to remain in qualified historical buildings or structures shall be evaluated for their condition and for loads required by this code. The structural survey required in Section 8-703 of the CHBC shall document existing conditions, reinforcement, anchorage, deterioration and other factors pertinent to establishing allowable stresses, strength levels and adequacy of the archaic materials. The remaining portion of this chapter provides additional specific requirements for commonly encountered archaic materials.
SECTION 8-805 — MASONRY
For adobe, see Section 8-806.
8-805.1 Existing solid masonry. Existing solid masonry walls of any type, except adobe, may be allowed, without testing, a maximum ultimate strength of 9 pounds per square inch (62.1 kPa) in shear where there is a qualifying statement by the architect or engineer that an inspection has been made, that mortar joints are filled and that both brick and mortar are reasonably good. The shear stress above applies to unreinforced masonry, except adobe, where the maximum ratio of unsupported height or length to thickness does not exceed 13, and where minimum quality mortar is used or exists. Wall height or length is measured to supporting or resisting elements that are at least twice as stiff as the tributary wall. Stiffness is based on the gross section. Shear stress may be increased by the addition of 10 percent of the axial direct stress due to the weight of the wall directly above.
CHBC § 3307.2 High relevance — show source text
Exception: Approved temporary means of egress and accessible means of egress systems and facilities.
3307.2 Water supply for fire protection. An approved water supply for fire protection, either temporary or permanent, shall be made available as soon as combustible building materials arrive on the site, on commencement of vertical combustible construction and on installation of a standpipe system in buildings under construction, in accordance with Sections 3307.2.1 through 3307.4.
Exception: The fire code official is authorized to reduce the fire-flow requirements for isolated buildings or a group of buildings in rural areas or small communities where the development of full fire-flow requirements is impractical.
3307.2.1 Combustible building materials. When combustible building materials of the building under construction are delivered to a site, a minimum fire flow of 500 gallons per minute (1893 L/m) shall be provided. The fire hydrant used to provide this fire-flow supply shall be within 500 feet (152 m) of the combustible building materials, as measured along an approved fire apparatus access lane. Where the site configuration is such that one fire hydrant cannot be located within 500 feet (152 m) of all combustible building materials, additional fire hydrants shall be required to provide coverage in accordance with this section.
3307.2.2 Vertical construction of Types III, IV and V construction. Prior to commencement of vertical construction of Type III, IV or V buildings that utilize any combustible building materials, the fire flow required by Sections 3307.2.2.1 through 3307.2.2.3 shall be provided, accompanied by fire hydrants in sufficient quantity to deliver the required fire flow and proper coverage.
3307.2.2.1 Fire separation up to 30 feet. Where a building of Type III, IV or V construction has a fire separation distance of less than 30 feet (9144 mm) from property lot lines, and an adjacent property has an existing structure or otherwise can be built on, the water supply shall provide either a minimum of 500 gallons per minute (1893 L/m) or the entire fire flow required for the building when constructed, whichever is greater.
3307.2.2.2 Fire separation of 30 feet up to 60 feet. Where a building of Type III, IV or V construction has a fire separation distance of 30 feet (9144 mm) up to 60 feet (18 288 mm) from property lot lines, and an adjacent property has an existing structure or otherwise can be built on, the water supply shall provide a minimum of 500 gallons per minute (1893 L/m) or 50 percent of the fire flow required for the building when constructed, whichever is greater.
3307.2.2.3 Fire separation of 60 feet or greater. Where a building of Type III, IV or V construction has a fire separation of 60 feet (18 288 mm) or greater from a property lot line, a water supply of 500 gallons per minute (1893 L/m) shall be provided.
3307.3 Vertical construction, Type I and II construction. If combustible building materials are delivered to the construction site, water supply in accordance with Section 3307.2.1 shall be provided. Additional water supply for fire flow is not required prior to commencing vertical construction of Type I and II buildings.
3307.4 Standpipe supply. Regardless of the presence of combustible building materials, the construction type or the fire separation distance, where a standpipe is required in accordance with Section 3307.5, a water supply providing a minimum flow of 500 gallons
CHBC § 8-9 High relevance — show source text
Bolt spacing shall not
exceed 6 feet (1830 mm) on center and shall not be less than 12 inches (305 mm) on center.
6. Other masonry based on tests or other substantiated data.
7. Embedded bolts to be tested as specified in regular code standards.
8. Stresses given may be increased for combinations of loads as specified in the regular code.
9. Adhesives shall be approved by the enforcing agency and installed in accordance with the manufacturer’s recommendations. All drilling dust shall be removed from drilled
holes prior to installation.|18 2025 CALIFORNIA HISTORICAL BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
8-9 MECHANICAL, PLUMBING AND ELECTRICAL REQUIREMENTS
SECTION 8-901 — PURPOSE, INTENT AND SCOPE
8-901.1 Purpose. The purpose of the CHBC is to provide regulations for the mechanical, plumbing and electrical systems of buildings designated as qualified historical buildings or properties. The CHBC requires enforcing agencies to accept any reasonable equivalent solutions to the regular code when dealing with qualified historical buildings or properties.
8-901.2 Intent. The intent of the CHBC is to preserve the integrity of qualified historical buildings or properties while providing a reasonable level of protection from fire, health and life safety hazards (hereinafter referred to as safety hazards) for the building occupants.
8-901.3 Scope. The CHBC shall be applied in conjunction with the regular code whenever compliance with the regular code is required for qualified historical buildings or properties.
8-901.4 Safety hazard. No person shall permit any safety hazard to exist on premises under their control, or fail to take immediate action to abate such hazard. Existing systems which constitute a safety hazard when operational may remain in place, provided they are completely and permanently rendered inoperative. Safety hazards created by inoperative systems shall not be permitted to exist. Requirements of the regular code concerning general regulations shall be complied with, except that the enforcing agency shall accept solutions which do not cause a safety hazard.
8-901.5 Energy conservation. Qualified historical buildings or properties covered by this part are exempted from compliance with energy conservation standards. When new nonhistorical lighting and space conditioning system components, devices, appliances and equipment are installed, they shall comply with the requirements of Title 24, Part 6, The California Energy Code, except where the historical significance or character-defining features are threatened.
SECTION 8-902 — MECHANICAL
8-902.1 General. Mechanical systems shall comply with the regular code unless otherwise modified by this chapter.
8-902.1.1 The provisions of the CHBC shall apply to the acceptance, location, installation, alteration, repair, relocation, replacement or addition of any heating, ventilating, air conditioning, domestic incinerators, kilns or miscellaneous heat-producing appliances or equipment within or attached to a historical building.
8-902.1.2 Existing systems which do not, in the opinion of the enforcing agency, constitute a safety hazard may remain in use.
8-902.1.3 The enforcing agency may approve any alternative to the CHBC which would achieve equivalent life safety.
8-902.2 Heating facilities. All dwelling-type occupancies covered under this chapter shall be provided with heating facilities. Woodburning or pellet stoves or fireplaces may be acceptable as heating facilities.
CHBC § 323-9843 High relevance — show source text
State Librarian [SL]
library.ca.gov csllaw@library.ca.gov (916) 323-9843 Public Library Construction & Renovation
2025 CALIFORNIA HISTORICAL BUILDING CODE v
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
HOW TO DETERMINE WHERE CHANGES HAVE BEEN MADE
Symbols in the margins indicate where changes have been made or language has been deleted.
This symbol indicates that a change has been made.
- This symbol indicates deletion of language.
vi 2025 CALIFORNIA HISTORICAL BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
PART 8 CONTAINS ALTERNATIVE REGULATIONS
FOR QUALIFIED HISTORICAL BUILDINGS
The California Historical Building Code (CHBC) is unique among state regulations. The authoring of the original CHBC required state agencies promulgating regulations for building construction to work in harmony with representatives of other design and construction disciplines. The result was a totally new approach to building codes for historical structures, which maintains currently acceptable life safety standards. These regulations are also unique in that they are performance oriented rather than prescriptive. The provisions of the CHBC are to be applied by the enforcing authority of every city, county, city and county, or state agency in permitting repairs, alterations and additions necessary for the preservation, rehabilitation, relocation, related construction, change of use or continued use of a qualified historical building. The authority for use of the CHBC is vested in Sections 18950 through 18961 of the Health and Safety Code. Section 18954 states, “The building department of every city or county or other local agency that has jurisdiction over the enforcement of code within its legal authority shall apply the alternative standards and regulations adopted pursuant to Section 18959.5 in permitting repairs, alterations, and additions necessary for the preservation, restoration, rehabilitation, safety, moving, or continued use of a qualified historical building or structure. A state agency shall apply the alternative regulations adopted pursuant to Section 18959.5 in permitting repairs, alterations, and additions necessary for the preservation, restoration, rehabilitation, safety, moving, or continued use of a qualified historical building or structure.” However, be aware that in order to use the CHBC, the structure under consideration must be qualified by being designated as an historical building or structure. Section 18955 states, “For the purposes of this part, a qualified historical building or structure is any structure or property, collection of structures, and their related sites deemed of importance to the history, architecture, or culture of an area by an appropriate local or state governmental jurisdiction. This shall include historical buildings or structures on existing or future national, state or local historical registers or official inventories, such as the National Register of Historic Places, State Historical Landmarks, State Points of Historical Interest, and city or county registers or inventories of historical or architecturally significant sites, places, historic districts, or landmarks. This shall also include places, locations, or sites identified on these historical registers or official inventories and deemed of importance to the history, architecture, or culture of an area by an appropriate local or state governmental jurisdiction.” The regulations of the CHBC have the same authority as state law and are to be considered as such. Liability is the same as for prevailing law. The intent of the CHBC is to save California’s architectural heritage by recognizing the unique construction problems inherent in historical buildings and by providing a code to deal with these problems.
CHBC § 8-404 High relevance — show source text
Exception: When an automatic sprinkler system is provided throughout the building, existing finishes shall be approved.
SECTION 8-404 — WOOD LATH AND PLASTER
Wood lath and plaster walls may be considered in accordance with codes, standards and listings published prior to 1943 whereby a wood stud wall assembly with gypsum or lime plaster on hand split or sawn wooden lath obtains a one-half-hour fire-resistive rating. This rating may be increased for interior walls to as much as one hour by filling the wall with mineral fiber or glass fiber.
SECTION 8-405 — OCCUPANCY SEPARATION
See Chapter 8-3.
SECTION 8-406 — MAXIMUM FLOOR AREA
See Chapter 8-3.
SECTION 8-407 — VERTICAL SHAFTS
Vertical shafts need not be enclosed when such shafts are blocked at every floor level by the installation of not less than 2 full inches (51 mm) of solid wood or equivalent construction to prevent the initial passage of smoke and flame. Automatic sprinkler systems or other solutions may be considered on a case-by-case basis, in lieu of enclosure of vertical shafts and stairwells.
SECTION 8-408 — ROOF COVERING
Existing or original roofing materials may be repaired or reconstructed subject to the following requirements:
- The original or historical roofing system shall be detailed or modified as necessary in order to be capable of providing shelter while preserving the historical materials and appearance of the roof.
2025 CALIFORNIA HISTORICAL BUILDING CODE 7
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
FIRE PROTECTION
- Wooden roof materials may be utilized where fire resistance is required, provided they are treated with fire-retardant treatments to achieve a Class “B” roof covering rating. Wood roofing in state designated Urban Wildland and High Fire Zones shall be permitted when installed in Class “A” assemblies.
- Jurisdictions that prohibit wood roofing materials for application as roof coverings and roof assemblies shall submit documentation for the adoption. Express Terms, statement of reasons and minutes of the action by the adopting authority Health and Safety Code, Section 18959(f).
SECTION 8-409 — FIRE ALARM SYSTEMS
Every qualified historical building or property shall be provided with fire alarm systems as required for the use or occupancy by the regular code or other approved alternative.
SECTION 8-410 — AUTOMATIC SPRINKLER SYSTEMS
8-410.1 Every qualified historical building or property which cannot be made to conform to the construction requirements specified in the regular code for the occupancy or use, and which constitutes a distinct fire hazard (for definition of “Distinct Hazard,” see Chapter 8-2), shall be deemed to be in compliance if provided with an automatic sprinkler system or a life safety system or other technologies as approved by the enforcing agency. (“Automatic” is defined in the regular code. “Sprinkler System” is defined in this section.)
8-410.2 When required by the CHBC, an automatic sprinkler system is defined by the following standards as adopted by the State Fire Marshal (for nonhazardous occupancies).
- Buildings of four stories or less: NFPA 13R.
- For floors above the fourth, NFPA 13.
CHBC § 8-102.1.1 High relevance — show source text
- State agencies. All state agencies shall apply the provisions of the CHBC in permitting repairs, alterations and additions necessary for the preservation, restoration, rehabilitation, safety, relocation, reconstruction or continued use of qualified historical buildings or properties.
8-102.1.1 Additions, alterations and repairs. It is the intent of the CHBC to allow nonhistorical expansion or addition to a qualified historical building or property, provided nonhistorical additions shall conform to the requirements of the regular code (as defined in Chapter 8-2).
8-102.1.2 Relocation. Relocated qualified historical buildings or properties shall be sited to comply with the regular code or with the solutions listed in the CHBC. Nonhistorical new construction related to relocation shall comply with the regular code. Reconstruction and restoration related to relocation is permitted to comply with the provisions in the CHBC.
8-102.1.3 Change of occupancy. For change of use or occupancy, see Chapter 8-3, Use and Occupancy.
8-102.1.4 Continued use. Qualified historical buildings or properties may have their existing use or occupancy continued if such use or occupancy conformed to the code or to the standards of construction in effect at the time of construction, and such use or occupancy does not constitute a distinct hazard to life safety as defined in the CHBC.
8-102.1.5 Unsafe buildings or properties. When a qualified historical building or property is determined to be unsafe as defined in the regular code, the requirements of the CHBC are applicable to the work necessary to correct the unsafe conditions. Work to remediate the buildings or properties need only address the correction of the unsafe conditions, and it shall not be required to bring the entire qualified historical building or property into compliance with regular code.
8-102.1.6 Additional work. Qualified historical buildings or properties shall not be subject to additional work required by the regular code, regulation or ordinance beyond that required to complete the work undertaken. Certain exceptions for accessibility and for distinct hazards exist by mandate and may require specific action, within the parameters of the CHBC.
SECTION 8-103 — ORGANIZATION AND ENFORCEMENT
8-103.1 Authority. The state or local enforcing agency, pursuant to authority provided under Section 18954 of the Health and Safety Code, shall administer and enforce the provisions of the CHBC in permitting repairs, alterations and additions necessary for the preservation, restoration, reconstruction, rehabilitation, relocation or continued use of a qualified historical building or property.
8-103.2 State enforcement. All state agencies pursuant to authority provided under Section 18954 and Section 18961 of the Health and Safety Code shall administer and enforce the CHBC with respect to qualified historical buildings or properties under their respective jurisdiction.
8-103.3 Liability. Prevailing law regarding immunity of building officials is unaffected by the use and enforcement of the CHBC.
2025 CALIFORNIA HISTORICAL BUILDING CODE 1
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ADMINISTRATION
SECTION 8-104 — REVIEW AND APPEALS
8-104.1 State Historical Building Safety Board (SHBSB or Board). In order to provide for interpretation of the provisions of the CHBC and to hear appeals, the SHBSB shall act as an appeal and review body to state and local agencies or any affected party.
**8-104.2 SHBSB review.
CHBC § 8-301 High relevance — show source text
Section
8-301 Purpose and Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8-302 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8-303 Residential Occupancies. . . . . . . . . . . . . . . . . . . . . . . . . 5
CHAPTER 8-4 FIRE PROTECTION. . . . . . . . . . . . . . . . . . . . . . . 7
Section
8-401 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . . 7
8-402 Fire-resistive Construction . . . . . . . . . . . . . . . . . . . . . . . 7
8-403 Interior Finish Materials. . . . . . . . . . . . . . . . . . . . . . . . . . 7
8-404 Wood Lath and Plaster. . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8-405 Occupancy Separation . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8-406 Maximum Floor Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8-407 Vertical Shafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8-408 Roof Covering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8-409 Fire Alarm Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8-410 Automatic Sprinkler Systems. . . . . . . . . . . . . . . . . . . . . 8 8-411 Other Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8-412 High-rise Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
CHAPTER 8-5 MEANS OF EGRESS . . . . . . . . . . . . . . . . . . . . . . 9
Section
8-501 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . . 9 8-502 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8-503 Escape or Rescue Windows and Doors. . . . . . . . . . . . 10 8-504 Railings and Guardrails . . . . . . . . . . . . . . . . . . . . . . . . . 10
CHBC § 11.5 High relevance — show source text
5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level|1.
Ordinary
temperature,
quick-response
sprinklers,
maximum 8 feet
3 inches
horizontal
spacing
2.
One line of
sprinklers at the
6-foot level and
the 11.5-foot
level of storage
3.
Locate in
longitudinal flue
space,
staggered
vertical
4.
Shields required
where multiple-
level| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Maximum
spacing|Maximum
spacing|100 ft2/head|100 ft2/head| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Area
(square feet)|Ordinary
temperature|Not
Applicable|Not
Applicable| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Area
(square feet)|High
temperature|2,000b|2,000b| |TABLE 5704.3.6.3(8)—AUTOMATIC SPRINKLER PROTECTION REQUIREMENTS FOR
CLASS I LIQUID STORAGE IN METAL CONTAINERS OF 1-GALLON CAPACITY OR LESS WITH UNCARTONED
OR CASE-CUT SHELF DISPLAY UP TO 6.5 FEET, AND PALLETIZED STORAGE ABOVE IN A DOUBLE-ROW RACK ARRAYa|CEILING SPRINKLER DESIGN AND DEMAND|Density
(gpm/ft2)|Density
(gpm/ft2)|0.60|0.60| |**TABLE 5704.3.6.
Frequently asked questions
Can I always use sprinklers instead of upgrading walls to one‑hour fire rating?
Yes — for an eligible qualified historical building the CHBC allows the fire‑resistive requirement to be satisfied by an automatic sprinkler system designed for exposure protection; acceptance is subject to the enforcing agency and the specific requirements of § 8-402.1 and § 8-402.2 .
Do exterior sprinklers have to be connected to a separate supply or can they use the domestic water line?
The CHBC permits exterior sprinkler systems to be connected to the domestic water supply on the supply‑main side of the building shut‑off valve, provided the shut‑off valve is locked open if one is installed, per § 8-402.1 .
Can historic single‑pane windows and wood doors remain in interior one‑hour walls?
Yes — historical glazing materials and solid wood unrated doors may be approved within interior walls that would otherwise require a one‑hour rating if the area has operable windows/doors with appropriate smoke seals and is protected by an automatic sprinkler system, per § 8-402.3 .
If I don’t want to install sprinklers, what are my other options?
Under § 8-402.2 you may provide an approved life safety evaluation or pursue other alternative measures that the enforcing agency approves as equivalent to the one‑hour upgrade .
Who approves these CHBC alternatives?
The enforcing agency (local or state building/fire authority) reviews and approves alternatives under the CHBC. Appeals and interpretations can be brought to the State Historical Building Safety Board where applicable .
More in California Historical Building Code
Ask about the CHBC
Get cited, plain-English answers on the California Historical Building Code for your project — any code section, any scenario.
Start Free Trial