CHBC · California Historical Building Code

When must vertical shafts or area separation walls be provided or can they be modified?

Q: When exactly can a vertical shaft remain unenclosed?

When each shaft opening is blocked at every floor by not less than 2 full inches (51 mm) of solid wood or equivalent construction to prevent initial passage of smoke and flame — per § 8-407 . Alternatives such as sprinklers may be accepted by the enforcing agency.

Q: What is the 15,000 sq ft rule I keep seeing?

§ 8-302.4 says a one‑story qualified historical building may have a floor area up to 15,000 sq ft unless otherwise permitted; Chapter 8-3 contains the full context and exceptions.

Q: If my historic building is two stories and residential, are area separation walls required?

Residential occupancies of two stories or less may be exempt from area‑separation walls if they have a complete fire alarm and annunciation system and exiting conform to regular code — see § 8-302.4 .

Q: Who approves alternative solutions (sprinklers, other measures)?

The enforcing agency must approve alternatives; the CHBC repeatedly notes that sprinklers or other measures are considered on a case‑by‑case basis and may substitute for certain requirements. See § 8-407 and § 8-402.2 .

For homeowners: In the California Historical Building Code a vertical shaft in a qualified historic building can stay open if each floor opening is blocked with at least 2 inches (51 mm) of solid wood (or equivalent). Area‑separation (fire) walls and maximum area rules live in Chapter 8‑3 (15,000 sq ft baseline) and fire‑resistive alternatives like sprinklers are covered in Chapter 8‑4 — sprinklers or other measures may substitute but must be approved by the enforcing agency.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

In the CHBC the primary rule for vertical shafts is that they need not be enclosed if they are blocked at every floor with not less than 2 full inches (51 mm) of solid wood or equivalent to prevent the initial passage of smoke and flame — or an approved alternative such as an automatic sprinkler system may be accepted by the enforcing agency in lieu of enclosure. This requirement is stated in § 8-407. For maximum floor area and when area separation walls (fire/area separation) apply, the CHBC directs you to the Chapter 8-3 provisions (see § 8-406 and § 8-302.6), which in turn reference specific floor-area limits and fire-resistive construction alternatives.

The simplest rule: vertical shafts in qualified historical buildings may remain unenclosed if each floor opening is blocked with at least 2 in (51 mm) solid wood (or equivalent); otherwise use an approved alternative such as a sprinkler system.

Requirements in detail

Vertical shafts (what the CHBC actually says)

What is allowed: Vertical shafts need not be enclosed in a qualified historical building if each shaft is blocked at every floor by the installation of not less than 2 full inches (51 mm) of solid wood or equivalent construction intended to prevent the initial passage of smoke and flame. This is the explicit CHBC provision in § 8-407.
Alternatives: The CHBC explicitly permits consideration of automatic sprinkler systems or other solutions on a case‑by‑case basis as an approved substitute for full shaft enclosure; such alternatives require approval by the enforcing agency. See § 8-407 and the related Chapter 8-4 provisions for sprinkler acceptance.

Area separation walls / Maximum floor area (how CHBC treats area separation)

Where to look: § 8-406 refers you to Chapter 8-3 for maximum floor area rules; Chapter 8-3 sets the numeric thresholds and exceptions (see § 8-302.4).
Key numeric rule: A one‑story qualified historical building may have a floor area up to 15,000 sq ft unless otherwise permitted by regular code. There is an exception that allows historical buildings to be unlimited in floor area without fire‑resistive area separation walls when an automatic sprinkler is provided, or for certain residential occupancies of two stories or less with a full fire alarm and compliant exiting. See § 8-302.4.

Fire-resistive construction and modifying separations

Reference: § 8-302.6 directs you to Chapter 8-4 for fire‑resistive construction requirements and alternatives; Chapter 8-4 contains the rules for when fire-resistive upgrades can be reduced or replaced with alternatives like sprinklers or a life-safety evaluation (for example, see § 8-402).
Practical effect: The CHBC allows reduction of certain fire‑resistive requirements (for example, one‑hour construction upgrades) where the building is provided with an automatic sprinkler system, an approved life‑safety evaluation, or other alternatives approved by the enforcing agency. See § 8-402.2.

Decision-relevant table (quick reference)

Decision factor	Threshold / value	Effect on vertical shafts / walls	Code Reference
Vertical shaft blocking thickness	2 in (51 mm) solid wood (minimum)	Allows shaft to remain unenclosed if blocked at every floor	§ 8-407
Acceptance of non‑enclosure via sprinkler	N/A — automatic sprinkler system may be considered	Sprinkler may be accepted in lieu of enclosure on a case-by-case basis	§ 8-407 and § 8-410
One‑story max floor area (baseline)	15,000 sq ft	Limit for one‑story qualified historical building unless otherwise allowed	§ 8-302.4 (Chapter 8-3)
Unlimited area without area‑separation walls	When automatic sprinkler provided OR certain residential ≤ 2 stories with full alarm	Area separation walls not required in these exceptions	§ 8-302.4
Where to find fire‑resistive rules	N/A — see Chapter 8-4	Fire-resistive construction and alternatives (sprinklers, life-safety eval) are handled here	§ 8-302.6 and § 8-402

Exceptions & special cases

The CHBC explicitly allows the enforcing agency to accept automatic sprinkler systems or other solutions in place of shaft enclosure or area separations; these are case‑by‑case decisions and require approval. See § 8-407 and Chapter 8-4 provisions.
For maximum floor area the CHBC provides exceptions to the 15,000 sq ft baseline: an automatic sprinkler system installed throughout the building removes the area‑separation requirement; a residential building of two stories or less with a full fire alarm system and compliant exiting may also be exempt from area separation walls. See § 8-302.4.
The CHBC permits the use of approved life‑safety evaluations and other alternative measures in lieu of some fire‑resistive upgrades (see § 8-402.2); these alternatives will affect whether area‑separation walls or shaft enclosures are required.

Common mistakes

Assuming CHBC always follows regular CBC enclosure rules. CHBC provides explicit alternatives for qualified historical buildings; read § 8-407 and Chapter 8-3/8-4 rather than applying new‑construction rules verbatim.
Missing the 2 in (51 mm) minimum detail for blocking vertical shafts — thinner blocking or non‑equivalent materials do not meet § 8-407 unless the enforcing agency approves an alternative.
Assuming a sprinkler system automatically removes all other requirements. The CHBC allows sprinklers as an alternative, but the enforcing agency must approve the substitution and other conditions (e.g., sprinkler design standard, fire alarm) may apply (see § 8-410 and § 8-402).
Confusing gross vs net floor area when checking the 15,000 sq ft threshold. Chapter 2 / regular code definitions control area calculations referenced by Chapter 8 (see cross‑references in CHBC).

Worked example — applying the rule with numbers

Scenario: A three‑story qualified historical commercial building (each floor 4,500 sq ft; total 13,500 sq ft) has an existing vertical service shaft (mechanical duct chase) that is open between floors. There is no building‑wide sprinkler system.

Vertical shaft requirement: Because the building is a qualified historical building, the owner may leave the shaft unenclosed provided each floor opening in the shaft is blocked with at least 2 in (51 mm) of solid wood or equivalent at the floor plane to prevent the initial passage of smoke and flame. This meets § 8-407.
Area separation / floor area: The building is a three‑story building and total floor area is below the one‑story 15,000 sq ft baseline (that baseline applies to one‑story limits); multi‑story buildings follow regular code for some aspects but Chapter 8-3/§ 8-302 addresses maximums and exceptions. Because this building is not exceeding CHBC exceptions, area separation walls are not automatically required on that basis; if the owner wants to remove blocking entirely, they would either need to provide an approved alternative (for example, a building‑wide sprinkler system accepted by the enforcing agency) or enclose the shaft to meet regular code requirements. See § 8-302.4, § 8-406, and § 8-407.

Practical takeaway: In this specific case, install/retain 2 in blocking at each floor to comply with § 8-407; if owner prefers to remove blocking, they must obtain an approved alternative (for example, a sprinkler system accepted per § 8-410 / enforcement approval).

Related provisions

§ 8-407 — Vertical shafts (blocking, alternative acceptance).
§ 8-302.6 — Fire‑resistive construction; directs to Chapter 8-4.
§ 8-406 — Maximum floor area (see Chapter 8-3).
§ 8-302.4 — Maximum floor area numeric limit and exceptions (15,000 sq ft baseline; sprinkler and residential exceptions).
§ 8-402 — Fire‑resistive construction alternatives (sprinklers, life‑safety eval).
§ 8-410 — Automatic sprinkler systems (definitions and when they satisfy CHBC requirements).

Code references

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

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:
1. 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.
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FIRE PROTECTION
1. 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.
2. 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).
1. Buildings of four stories or less: NFPA 13R.
2. For floors above the fourth, NFPA 13.
CHBC § 8-402 Medium 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:
1. An automatic sprinkler system throughout. See Section 8-410 for automatic sprinkler systems.
2. An approved life safety evaluation.
3. 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:
1. 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 § 2607.4 Medium relevance — show source text

Exceptions:

In structures provided with approved flame barriers extending 30 inches (760 mm) beyond the exterior wall in the plane of the floor, a vertical separation is not required at the floor except that provided by the vertical thickness of the flame barrier projection.
Veneers of approved weather-resistant light-transmitting plastics used as exterior siding in buildings of Type V construction in compliance with Section 1405.
The area of light-transmitting plastic wall panels in exterior walls of greenhouses shall be exempt from the area limitations of Table 2607.4 but shall be limited as required for unprotected openings in accordance with Section 705.9.

TABLE 2607.4—AREA LIMITATION AND SEPARATION REQUIREMENTS FOR LIGHT-TRANSMITTING PLASTIC WALL PANELSa	Col2	Col3	Col4	Col5	Col6
FIRE SEPARATION DISTANCE (feet)	CLASS OF PLASTIC	MAXIMUM PERCENTAGE AREA OF EXTERIOR WALL IN PLASTIC WALL PANELS	MAXIMUM SINGLE AREA OF PLASTIC WALL PANELS (square feet)	MINIMUM SEPARATION OF PLASTIC WALL PANELS (feet)	MINIMUM SEPARATION OF PLASTIC WALL PANELS (feet)
FIRE SEPARATION DISTANCE (feet)	CLASS OF PLASTIC	MAXIMUM PERCENTAGE AREA OF EXTERIOR WALL IN PLASTIC WALL PANELS	MAXIMUM SINGLE AREA OF PLASTIC WALL PANELS (square feet)	Vertical	Horizontal
Less than 6	—	Not Permitted	Not Permitted	—	—
6 or more but less than 11	CC1	10	50	8	4
6 or more but less than 11	CC2	Not Permitted	Not Permitted	—	—
11 or more but less than or equal to 30	CC1	25	90	6	4
11 or more but less than or equal to 30	CC2	15	70	8	4
Over 30	CC1	50	Not Limited	3b	0
Over 30	CC2	50	100	6b	3
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2. a. For combinations of plastic glazing and plastic wall panel areas permitted, see Section 2607.6. b. For reductions in vertical separation allowed, see Section 2607.4.	For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2. a. For combinations of plastic glazing and plastic wall panel areas permitted, see Section 2607.6. b.

CHBC § 8-301 Medium 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 § 8-7 Medium relevance — show source text
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8-7 STRUCTURAL REGULATIONS

SECTION 8-701 — PURPOSE, INTENT AND SCOPE

8-701.1 Purpose. The purpose of the CHBC is to provide alternative regulations to the regular code for the structural safety of buildings designated as 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.

8-701.2 Intent. The intent of this chapter is to encourage the preservation of qualified historical buildings or structures while providing standards for a minimum level of building performance with the objective of preventing partial or total structural collapse such that the overall risk of life-threatening injury as a result of structural collapse is low.

8-701.3 Application. The alternative structural regulations provided by Section 8-705 are to be applied in conjunction with the regular code whenever a structural upgrade or reconstruction is undertaken for qualified historical buildings or properties.

SECTION 8-702 — GENERAL

8-702.1 The CHBC shall not be construed to allow the enforcing agency to approve or permit a lower level of safety of structural design and construction than that which is reasonably equivalent to the regular code provisions in occupancies which are critical to the safety and welfare of the public at large, including, but not limited to, public and private schools, hospitals, municipal police and fire stations and essential services facilities.

8-702.2 Nothing in these regulations shall prevent voluntary and partial seismic upgrades when it is demonstrated that such upgrades will improve life safety and when a full upgrade would not otherwise be required.

SECTION 8-703 — STRUCTURAL SURVEY

8-703.1 Scope. When a structure or portion of a structure is to be evaluated for structural capacity under the CHBC, it shall be surveyed for structural conditions by an architect or engineer knowledgeable in historical structures. The survey shall evaluate deterioration or signs of distress. The survey shall determine the details of the structural framing and the system for resistance of gravity and lateral loads. Details, reinforcement and anchorage of structural systems and veneers shall be determined and documented where these members are relied on for seismic lateral resistance.

8-703.2 The results of the survey shall be utilized for evaluating the structural capacity and for designing modifications to the structural system to reach compliance with this code.

8-703.3 Historical records. Past historical records of the structure or similar structures may be used in the evaluation, including the effects of subsequent alterations.

SECTION 8-704 — NONHISTORICAL ADDITIONS AND NONHISTORICAL ALTERATIONS

8-704.1 New nonhistorical additions and nonhistorical alterations which are structurally separated from an existing historical building or structure shall comply with regular code requirements.

8-704.2 New nonhistorical additions which impose vertical or lateral loads on an existing structure shall not be permitted unless the affected part of the supporting structure is evaluated and strengthened, if necessary, to meet regular code requirements.

Note: For use of archaic materials, see Chapter 8-8.

SECTION 8-705 — STRUCTURAL REGULATIONS

CHBC § 701-30 Medium relevance — show source text

SECTION BB104—FIRE AREA

BB104.1 General. The fire area shall be the total floor area of all floor levels within the exterior walls, and under the horizontal projec- tions of the roof of a building, except as modified in Section 4.

BB104.2 Area separation. Portions of buildings which are separated by one or more 4-hour area separation walls constructed in accor- dance with the building code, without openings and provided with a 30-inch (762 mm) parapet, are allowed to be considered as separate fire areas.

BB104.3 Type I and Type IB construction. The fire area of buildings constructed of Type I and Type IB construction shall be the area of the three largest successive floors.

SECTION BB105—FIRE-FLOW REQUIREMENTS FOR BUILDINGS

BB105.1 The minimum fire flow and flow duration for school buildings shall be as specified in Table BB105.1.

Exception: A reduction in required fire flow of up to 75 percent is allowed when the building is provided with an approved automatic sprinkler system. When a reduction in fire flow is used, fire flow shall not be less than 1500 GPM.

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APPENDIX BB—FIRE-FLOW REQUIREMENTS FOR BUILDINGS

TABLE BB105.1—MINIMUM REQUIRED FIRE-FLOW AND FLOW DURATION FOR BUILDINGS	Col2	Col3	Col4	Col5	Col6	Col7
*FIRE AREA (square feet)*	*FIRE AREA (square feet)*	*FIRE AREA (square feet)*	*FIRE AREA (square feet)*	*FIRE AREA (square feet)*	*FIRE-FLOW* *(gallons per* *minute)b*	*FLOW* *DURATION* *(hours)*
*Type IA and IB a*	*Type IIA and IIIA a*	*Type IV and V-A a*	*Type IIB and IIIB a*	*Type V-B a*	*Type V-B a*	*Type V-B a*
0-22,700	0-12,700	0-8,200	0-5,900	0-3,600	1,500	2
22,701-30,200	12,701-17,000	8,201-10,900	5,901-7,900	3,601-4,800	1,750	1,750
30,201-38,700	17,001-21,800	10,901-12,900	7,901-9,800	4,801-6,200	2,000	2,000
38,701-48,300	21,801-24,200	12,901-17,400	9,801-12,600	6,201-7,700	2,250	_2,

CHBC § 1011.7.1 Medium relevance — show source text
1011.7.1 Exterior wall rating for change of occupancy classification to a higher-hazard category. Where a change of occupancy classification is made to a higher hazard category as shown in Table 1011.7, exterior walls shall have fire-resistance, exterior opening areas and opening protectives as required by the California Building Code .

Exception: A 2-hour fire-resistance rating shall be allowed where the building does not exceed three stories in height and is classified as one of the following groups: A-2 and A-3 with an occupant load of less than 300, B, F, M or S.

1011.7.2 Exterior wall rating for change of occupancy classification to an equal or lesser-hazard category. Where a change of occupancy classification is made to an equal or lesser-hazard category as shown in Table 1011.7, existing exterior walls, including openings, shall be accepted.

1011.7.3 Opening protectives. Openings in exterior walls shall be protected as required by the California Building Code . Where openings in the exterior walls are required to be protected because of their distance from the lot line, the sum of the area of such openings shall not exceed 50 percent of the total area of the wall in each story.

Exceptions:
1. Where the California Building Code permits openings in excess of 50 percent.
2. Protected openings shall not be required in buildings of Group R occupancy that do not exceed three stories in height and that are located not less than 3 feet (914 mm) from the lot line.
3. Exterior opening protectives are not required where an automatic sprinkler system has been installed throughout.
4. Exterior opening protectives are not required where the change of occupancy group is to an equal or lower hazard classification in accordance with Table 1011.7.
1011.8 Enclosure of vertical shafts. Enclosure of vertical shafts shall be in accordance with Sections 1011.8.1 through 1011.8.4.

1011.8.1 Minimum requirements. Vertical shafts shall be designed to meet the California Building Code requirements for atriums or the requirements of this section.

1011.8.2 Stairways. Where a change of occupancy classification is made to a higher-hazard category as shown in Table 1011.5, interior stairways shall be enclosed as required by the California Building Code .

Exceptions:
1. In other than Group I occupancies, an enclosure shall not be required for openings serving only one adjacent floor and that are not connected with corridors or stairways serving other floors.
2. Unenclosed existing stairways need not be enclosed in a continuous vertical shaft if each story is separated from other stories by 1-hour fire-resistance-rated construction and all exit corridors are sprinklered in accordance with the California Building Code . The openings between the corridor and the tenant space shall have not fewer than one sprinkler above the openings on the tenant side.
3. Existing penetrations of stairway enclosures shall be accepted if they are protected in accordance with the California Building Code .
1011.8.3 Other vertical shafts. Interior vertical shafts other than stairways, including but not limited to elevator hoistways and service and utility shafts, shall be enclosed as required by the California Building Code where there is a change of use to a higherhazard category as specified in Table 1011.5.
CHBC § 6-1 Medium relevance — show source text
Equation 6-1 ( U tc / U ac ) + ( U tw / U aw ) ≤ 1

where:

U tc = Total unprotected mass timber ceiling areas. U ac = Allowable unprotected mass timber ceiling area conforming to Exception 1.1 of Section 602.4.2.2.2.

U tw = Total unprotected mass timber wall areas.

U aw = Allowable unprotected mass timber wall area conforming to Exception 1.2 of Section 602.4.2.2.2.

602.4.2.2.4 Separation distance between unprotected mass timber elements. In each dwelling unit or fire area, unprotected portions of mass timber walls shall be not less than 15 feet (4572 mm) from unprotected portions of other walls measured horizontally along the floor.

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TYPES OF CONSTRUCTION

602.4.2.3 Floors. The floor assembly shall contain a noncombustible material not less than 1 inch (25 mm) in thickness above the mass timber. Floor finishes in accordance with Section 804 shall be permitted on top of the noncombustible material. Except where unprotected mass timber ceilings are permitted in Section 602.4.2.2.2, the underside of floor assemblies shall be protected in accordance with Section 602.4.1.2.

602.4.2.4 Roofs. The interior surfaces of roof assemblies shall be protected in accordance with Section 602.4.2.2 except, in nonoccupiable spaces, they shall be treated as a concealed space with no portion left unprotected. Roof coverings in accordance with Chapter 15 shall be permitted on the outside surface of the roof assembly.

602.4.2.5 Concealed spaces. Concealed spaces shall not contain combustibles other than electrical, mechanical, fire protection, or plumbing materials and equipment permitted in plenums in accordance with the California Mechanical Code, and shall comply with all applicable provisions of Section 718. Combustible construction forming concealed spaces shall be protected in accordance with Section 602.4.1.2.

602.4.2.6 Shafts. Shafts shall be permitted in accordance with Sections 713 and 718. Both the shaft side and room side of mass timber elements shall be protected in accordance with Section 602.4.1.2.

602.4.3 Type IV-C. Building elements in Type IV-C construction shall be protected in accordance with Sections 602.4.3.1 through 602.4.3.6. The required fire-resistance rating of building elements shall be determined in accordance with Section 703.2.

602.4.3.1 Exterior protection. The exterior side of walls of combustible construction shall be protected with noncombustible protection with a minimum assigned time of 40 minutes, as determined in Table 722.7.1(1).

CHBC § 3-17 Medium relevance — show source text

Applicants must ensure that when multiple service facilities (i.e., gas, electric, and telecommunications) are installed in close proximity (e.g., in a joint trench), a 12-inch minimum, radial separation is maintained where those facilities transition from below ground to above ground.

3-17 2022 – 2023

Section 3, Electric Service: Underground

3.3.8. (continued)

PG&E allows an exception to that rule when the separation is between PG&E secondary, electric-service conduit and gas-service piping. In this instance, the minimum separation distance may be reduced to 6 inches. Clearances between other facilities can be reduced only when the facility owners reach a mutual agreement.

When electric underground facilities cross under or over gas facilities, the minimum vertical separation between these facilities is 6 inches. The electric and gas facilities should cross at an angle between 45 degrees to 90 degrees. Crossings less than 45 degrees are considered to be parallel and require the minimum horizontal clearance between the two facilities.

12” Minimum

12” Minimum	Col2	Col3	Col4
6” Minimum Bedding Material S G T C 39” Minimum 2” 12” 3” * Increase Minimum Cover to 30” in the Franchise Area. 12” Minimum 4”	6” Minimum Bedding Material S G T C 39” Minimum 2” 12” 3” * Increase Minimum Cover to 30” in the Franchise Area. 12” Minimum 4”	6” Minimum Bedding Material S G T C 39” Minimum 2” 12” 3” * Increase Minimum Cover to 30” in the Franchise Area. 12” Minimum 4”	6” Minimum Bedding Material S G T C 39” Minimum 2” 12” 3” * Increase Minimum Cover to 30” in the Franchise Area. 12” Minimum 4”
			39” Minimum
3”
12”
4”
2”		Bedding Material	Bedding Material

Col1	Col2
24” Minimum Cover*

2”

Figure 3-6 Typical Joint Service Trench

Notes in reference to Figure 3-6 and Figure 3-7.

Trench depth will vary depending on conduit size.

Figure 3-7 PG&E Electric and Gas Service Trench

Soil compaction must meet PG&E’s and any applicable federal, state, county, and local requirements.
All separation and clearance dimensions must be met in Table 3-1 on Page 3-19.

CHBC § 7.62 Medium relevance — show source text
1. For occupancies in Groups R-2 and R-3, within the interior conditioned space of individual dwelling units, where the open-sided walking surface is located not more than 25 feet (7.62 meters) measured vertically to the floor or walking surface below, required guards shall not be less than 36 inches (914 mm) in height measured vertically above the adjacent walking surface. 3. For occupancies in Group R-3, and within individual dwelling units in occupancies in Group R-2, where the top of the guard serves as a handrail on the open sides of stairs, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) measured vertically from a line connecting the nosings. 4. The guard height in assembly seating areas shall comply with Section 1030.17 as applicable. 5. Along alternating tread devices and ship’s ladders, guards where the top rail serves as a handrail shall have height not less than 30 inches (762 mm) and not more than 34 inches (864 mm), measured vertically from a line connecting the leading edge of the treads. 6. In Group F occupancies where exit access stairways serve fewer than three stories and such stairways are not open to the public, and where the top of the guard also serves as a handrail, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) measured vertically from a line connecting the nosings.
[BE] 1015.4 Opening limitations. Required guards shall not have openings that allow passage of a sphere 4 inches (102 mm) in diameter from the walking surface to the required guard height.

Exceptions:
1. From a height of 36 inches (914 mm) to 42 inches (1067 mm), guards shall not have openings that allow passage of a sphere 4 [3] / 8 inches (111 mm) in diameter.
2. The triangular openings at the open sides of a stair, formed by the riser, tread and bottom rail shall not allow passage of a sphere 6 inches (152 mm) in diameter.
3. At elevated walking surfaces for access to and use of electrical, mechanical or plumbing systems or equipment, guards shall not have openings that allow passage of a sphere 21 inches (533 mm) in diameter.
4. In areas that are not open to the public within occupancies in Group I-3, F, H or S, and for alternating tread devices and ship’s ladders, guards shall not have openings that allow passage of a sphere 21 inches (533 mm) in diameter.
5. In assembly seating areas, guards required at the end of aisles in accordance with Section 1030.17.4 shall not have openings that allow passage of a sphere 4 inches (102 mm) in diameter up to a height of 26 inches (660 mm). From a height of 26 inches (660 mm) to 42 inches (1067 mm) above the adjacent walking surfaces, guards shall not have openings that allow passage of a sphere 8 inches (203 mm) in diameter.
6. Within individual dwelling units and sleeping units in Group R-2 and R-3 occupancies, guards on the open sides of stairs shall not have openings that allow passage of a sphere 4 [3] / 8 (111 mm) inches in diameter. 7. [SFM] In lifeguard towers not open to the public, guards shall not have openings which allow passage of a sphere 21 inches (533 mm) in diameter.

CHBC § 8-6 Medium relevance — show source text

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

APPENDIX A	Col2	Col3	Col4
CHAPTER 8-6—TABLE 1—PROVISION APPLICABILITY	CHAPTER 8-6—TABLE 1—PROVISION APPLICABILITY	CHAPTER 8-6—TABLE 1—PROVISION APPLICABILITY	CHAPTER 8-6—TABLE 1—PROVISION APPLICABILITY
	Title II Public Entities	Title III Private Entities	Title III Barrier Removal
SECTION 8-601 PURPOSE, INTENT, SCOPE 8-601.1 Purpose.The purpose of the CHBC is to provide alternative regulations to facilitate access and use by persons with disabilities to and throughout facilities designated as quali- fied historical buildings or properties. These regulations require enforcing agencies to accept alternatives to regular code when dealing with qualified historical buildings or properties. 8-601.2 Intent.The intent of this chapter is to preserve the integrity of qualified historical buildings and properties while providing access to and use by persons with disabilities. 8-601.3 Scope.The CHBC shall apply to every qualified historical building or property that is required to provide access to persons with disabilities. 1.Provisions of this chapter do not apply to new construction or reconstruction/replicas of historical buildings. 2. Where provisions of this chapter apply to alteration of qualified historical buildings or properties, alteration is defined in_ California Building Code_ (CBC), Chapter 2. 8-601.4 General application. The provisions in the CHBC apply to local, state and federal governments (Title II entities); alteration of commercial facilities and places of public accommodation (Title III entities); and barrier removal in commercial facilities and places of public accommodation (Title III entities). Except as noted in this chapter.	Applies	Applies	Applies
SECTION 8-602 — BASIC PROVISIONS 8-602.1 Regular code. The regular code for access for people with disabilities (Title 24, Part 2, Vol.1, Chapter 11B) shall be applied to qualified historical buildings or properties unless strict compliance with the regular code will threaten or destroy the historical significance or character-defining features of the building or property. 8-602.2 Alternative provisions.If the historical significance or character-defining features are threatened, alternative provisions for access may be applied pursuant to this chapter, provided the following conditions are met: 1.These provisions shall be applied only on an item-by-item or case-by-case basis. 2.Documentation is provided, including meeting minutes or letters, stating the reasons for the application of the alternative provisions. Such documentation shall be retained in the permanent file of the enforcing agency.	Applies	Applies	Applies
Section 8-603 — ALTERNATIVES 8-603.1 Alternative minimum standards.The alternative minimum standards for alter- ations of qualified historical buildings or facilities are referenced in Section 202.5 of the_ 2010_ ADA Standards for Accessible Design, as incorporated and set forth in federal regulation 28 CFR Pt. 36. **8-603.2 Entry.

CHBC § 8.3.2.5. Medium relevance — show source text
3. See Health and Safety Code Section 19966 for “Approved” as applied to factory-built housing as referenced in Section 1.8.3.2.5.

4. See Health and Safety Code Section 18201 for “Approved” as applied to mobilehome parks as referenced in Section 1.8.2.1.3. 5. See Health and Safety Code Section 18862.1 for “Approved” as applied to special occupancy parks as referenced in Section 1.8.2.1.3.

2025 CALIFORNIA BUILDING CODE 2-13

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DEFINITIONS

[A] APPROVED AGENCY. An established and recognized organization that is regularly engaged in conducting tests, furnishing inspection services or furnishing product evaluation or certification where such organization has been approved by the building official.

[HCD 1 & HCD 2] “Approved agency” shall mean “Listing agency” and “Testing agency.”

[DSA-SS, DSA-SS/CC] This term is synonymous with “laboratory of record” as referenced in Section 4-335 of the California Administra- tive Code.

[BS] APPROVED FABRICATOR. An established and qualified person, firm or corporation approved by the building official pursuant to Chapter 17 of this code.

APPROVED LISTING AGENCY. [HCD 1 & HCD 2] Any agency approved by the enforcing agency, unless otherwise provided by law, which is in the business of listing and labeling and which makes available at least an annual published report of such listings in which specific information is included that the product has been tested to recognized standards and found to comply.

[A] APPROVED SOURCE. An independent person, firm or corporation, approved by the building official, who is competent and experienced in the application of engineering principles to materials, methods or systems analyses.

APPROVED TESTING AGENCY. [HCD 1, HCD 2, DSA-AC & OSHPD 1, 1R, 2, 4 & 5] Any agency, which is determined by the enforcing agency, except as otherwise provided by law, to have adequate personnel and expertise to carry out the testing of systems, materials, types of construction, fixtures or appliances.

[BS] AREA (for masonry).

Gross cross-sectional. The area delineated by the out-to-out specified dimensions of masonry in the plane under consideration.

Net cross-sectional. The area of masonry units, grout and mortar crossed by the plane under consideration based on out-to-out specified dimensions.

[BG] AREA, BUILDING. The area included within surrounding exterior walls, or exterior walls and fire walls, exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.

[BE] AREA OF REFUGE. An area where persons unable to use stairways can remain temporarily to await instructions or assistance during emergency evacuation.

[BE] AREA OF SPORT ACTIVITY. That portion of an indoor or outdoor space where the play or practice of a sport occurs.

[BG] AREAWAY. A subsurface space adjacent to a building open at the top or protected at the top by a grating or guard.
CHBC § 8-302.3 Medium 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:
1. When provided with an automatic sprinkler, or
2. 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:
1. The building construction type and the exits conform to regular code, and
2. A complete building fire alarm and annunciation system is installed, and
3. 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 § 8.1.1 Medium relevance — show source text
Wall openings in waffle-grid and screen-grid walls shall be located such that not less than one-half of a vertical core occurs along each side of the opening.

R608.8.1.1 Horizontal reinforcement. Lintels complying with Section R608.8.2 shall be provided above wall openings equal to or greater than 2 feet (610 mm) in width.

Openings equal to or greater than 2 feet (610 mm) in width shall have not less than one No. 4 bar placed within 12 inches (305 mm) of the bottom of the opening. See Figure R608.8(1).

Horizontal reinforcement placed above and below an opening shall extend beyond the edges of the opening the dimension required to develop the bar in tension in accordance with Section R608.5.4.4.

Exception: Continuous horizontal wall reinforcement placed within 12 inches (305 mm) of the top of the wall story as required in Sections R404.1.3.2 and R608.6.2 is permitted in lieu of top or bottom lintel reinforcement required by Section R608.8.2 provided that the continuous horizontal wall reinforcement meets the location requirements specified in Figures R608.8(2), R608.8(3), and R608.8(4) and the size requirements specified in Tables R608.8(2) through R608.8(10).

R608.8.1.2 Vertical reinforcement. Not less than one No. 4 bar [Grade 40 (280 MPa)] shall be provided on each side of openings equal to or greater than 2 feet (610 mm) in width. The vertical reinforcement required by this section shall extend the full height of the wall story and shall be located within 12 inches (305 mm) of each side of the opening. The vertical reinforcement required on each side of an opening by this section is permitted to serve as reinforcement at the ends of solid wall segments in accordance with Section R608.7.2.2.2, provided it is located as required by the applicable detail in Figure R608.7.1.1(2). Where the vertical reinforcement required by this section is used to satisfy the requirements of Section R608.7.2.2.2 in waffle- and screen-grid walls, a concrete flange shall be created at the ends of the solid wall segments in accordance with Table R608.7.1.1(6), Note e. In the top-most story, the reinforcement shall terminate in accordance with Section R608.6.4.

R608.8.2 Lintels. Lintels shall be provided over all openings equal to or greater than 2 feet (610 mm) in width. Lintels with uniform loading shall conform to Sections R608.8.2.1 and R608.8.2.2, or Section R608.8.2.3. Lintels supporting concentrated loads, such as from roof or floor beams or girders, shall be designed in accordance with ACI 318.

R608.8.2.1 Lintels designed for gravity load-bearing conditions. Where a lintel will be subjected to gravity load conditions 1 through 5 of Table R608.8(1), the clear span of the lintel shall not exceed that permitted by Tables R608.8(2) through R608.8(8). The maximum clear span of lintels with and without stirrups in flat walls shall be determined in accordance with Tables R608.8(2) through R608.8(5), and constructed in accordance with Figure R608.8(2).

CHBC § 10.1.1 Medium relevance — show source text

FIGURE R602.10.1.1—BRACED WALL LINES

SPACING

SPACING SPACING

SPACING

BW	WL A BW SPACING BETWEEN	Col3	Col4	Col5	WL B BW SPACING BETWEEN	WL C BWL A BWL B BWL C BETWEEN BETWEEN	WL A BWL BETWEEN	L B BWL BETWEEN	Col10	L C
	BWL A-B	BWL A-B	BWL A-B	BWL A-B	BWL B-C	4′ MAX 4′ MAX 4′ MAX NOTE: IN THE ABSENCE OF A BRACED WALL LINE, BWL A, B, C SHALL END AT EXTERIOR WALL NO BRACED WALL LINE; ROOF AND FLOOR BEAR AT SAME ELEVATION BWL 1 BWL 1 END OF BUILDING SPACING BETWEEN BWL 1 AND END OF BUILDING BWL 2 WL 4 SPACING BETWEEN BWL 2-4 SPACING BETWEEN BWL 1-2 BWL A-B BWL B-C	BWL A-B	BWL B-C	BWL B-C
	BWL A-B	BWL A-B
BWL 1-3
BWL 1-3							4′ MAX 4′ MAX NO BRACED WALL LINE; ROOF AND FLOOR BEAR AT SAME ELEVATION	4′ MAX	4′ MAX
BWL 1-3					4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX
BWL 1-3
4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX
4′ MAX	4′ MAX	4′ MAX	4′ MAX	4′ MAX

TYPICAL BRACED WALL PLAN TYPICAL UPPER FLOOR BRACED WALL PLAN

For SI: 1 foot = 304.8 mm.

R602.10.1.2 Location of braced wall lines and permitted offsets. Each braced wall line shall be located such that no more than two-thirds of the required braced wall panel length is located to one side of the braced wall line. Braced wall panels shall be permitted to be offset up to 4 feet (1219 mm) from the designated braced wall line. Braced wall panels parallel to a braced wall line shall be offset not more than 4 feet (1219 mm) from the designated braced wall line location as shown in Figure R602.10.1.1.

Exterior walls parallel to a braced wall line shall be offset not more than 4 feet (1219 mm) from the designated braced wall line location as shown in Figure R602.10.1.1.

Interior walls used as bracing shall be offset not more than 4 feet (1219 mm) from a braced wall line through the interior of the building as shown in Figure R602.10.1.1.

CHBC § 902.1 Medium relevance — show source text
SECTION 902—SPECIAL USE AND OCCUPANCY

902.1 Reserved.

902.2 Group R-2.1 occupancies. Group R-2.1 occupancies shall be classified in accordance with Section 308.2 of the California Build- ing Code .

902.2.1 Smoke barriers in Group R-2.1 . In Group R-2.1 occupancies where the work area is on a story used for sleeping rooms for more than 30 care recipients, the story shall be divided into not fewer than two compartments by smoke barrier walls in accordance with Section 420.6 of the California Building Code .

902.3 Ambulatory care facilities. Where a Level 3 work area includes an existing ambulatory care facility, the following shall be provided:
1. A smoke compartment in accordance with Section 422.3 of the California Building Code, where the alteration results in an ambulatory care facility greater than 10,000 square feet on one story.
2. Separation from adjacent spaces in accordance with Section 422.2 of the California Building Code, where any such facility has the potential for four or more care recipients incapable of self-preservation at any time.
SECTION 903—BUILDING ELEMENTS AND MATERIALS

903.1 Existing shafts and vertical openings. Existing stairways that are part of the means of egress shall be enclosed in accordance with Section 802.2.1 from the highest work area floor to, and including, the level of exit discharge and all floors below.

903.2 Fire partitions in Group R-3. Fire separation in Group R-3 occupancies shall be in accordance with Section 903.2.1.

903.2.1 Separation required. Where the work area is in any attached dwelling unit in Group R-3 or any multiple single-family dwelling (townhouse), walls separating the dwelling units that are not continuous from the foundation to the underside of the roof sheathing shall be constructed to provide a continuous fire separation using construction materials consistent with the existing wall or complying with the requirements for new structures. Work shall be performed on the side of the dwelling unit wall that is part of the work area.

Exception: Where alterations or repairs do not result in the removal of wall or ceiling finishes exposing the structure, walls are not required to be continuous through concealed floor spaces.

903.3 Interior finish. Interior finish in exits serving the work area shall comply with Section 802.4 between the highest floor on which there is a work area to the floor of exit discharge.

903.4 Enhanced classroom acoustics. In Group E occupancies, where the work area is a Level 3 alteration, enhanced classroom acoustics shall be provided in all classrooms with a volume of 20,000 cubic feet (565 m [3] ) or less. Enhanced classroom acoustics shall comply with the reverberation time in Section 808 of ICC A117.1.

2025 CALIFORNIA EXISTING BUILDING CODE 9-3

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ALTERATIONS—LEVEL 3

SECTION 904—FIRE PROTECTION

904.1 Automatic sprinkler systems. An automatic sprinkler system shall be provided in accordance with Section 903 of the California Building and California Fire Codes.
CHBC § 8-804 Medium relevance — show source text
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. Higher-quality mortar may provide a greater shear value and shall be tested in accordance with Appendix A, Chapter A1 of the California Existing Building Code (CEBC) 2010 edition, and as modified by the CHBC.

8-805.2 Stone masonry.

8-805.2.1 Solid-backed stone masonry. Stone masonry solidly backed with brick masonry shall be treated as solid brick masonry as described in Section 8-805.1 and in the 2009 International Existing Building Code [®] (IEBC [®] ), provided representative testing and inspection verifies solid collar joints between stone and brick and that a reasonable number of stones lap with the brick wythes as headers or that steel anchors are present. Solid stone masonry where the wythes of stone effectively overlap to provide the equivalent header courses may also be treated as solid brick masonry.

8-805.2.2 Independent wythe stone masonry. Stone masonry with independent face wythes may be treated as solid brick masonry as described in Section 8-805.1 and the CEBC, provided representative testing and inspection verify that the core is essentially solid in the masonry wall and that steel ties are epoxied in drilled holes between outer stone wythes at floors, roof and not to exceed 4 feet (1219 mm) on center in each direction, between floors and roof. A reinforcing element shall exist or be provided at or near the top of all stone masonry walls.

2025 CALIFORNIA HISTORICAL BUILDING CODE 15

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ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION

8-805.2.3 Testing of stone masonry. Testing of stone masonry shall be similar to the 2010 CEBC requirements for brick masonry, except that representative stones which are not interlocked shall be pulled outward from the wall and shear area appropriately calculated after the test.
CHBC § 0.25 Medium relevance — show source text
g|NA|0.25g|(0.25)g|NA|0.25g|(0.25)g| |Oxidizer|3j|H-2 or H-3|10d, e|(10)d, e|(10)d, e|2d|(2)d|(2)d|2d|(2)d| |Oxidizer|2|H-3|250d, e|(250)d, e|(250)d, e|250d|(250)d|(250)d|50d|(50)d| |Oxidizer|1|NA|4,000e, f|(4,000)e, f|(4,000)e, f|4,000f|(4,000)f|(4,000)f|1,000f|(1,000)f| |Oxidizing gas|Gaseous|H-3|NA|NA|1,500d,e|NA|NA|1,500d, e|NA|NA| |Oxidizing gas|Liquefied|Liquefied|Liquefied|(150)d, e|NA|NA|(150)d, e|NA|NA|NA| |Pyrophoric|NA|H-2|4e, g|(4)e, g|50e, g|1g|(1)g|10e, g|0|0| |Unstable
(reactive)|4|H-1|1e, g|(1)e, g|10e, g|0.25g|(0.25)g|2e, g|0.25g|(0.25)g| |Unstable
(reactive)|3|H-1 or H-2|5d, e|(5)d, e|50d, e|1d|(1)d|10d, e|1d|(1)d| |Unstable
(reactive)|2|H-3|50d, e|(50)d, e|750d, e|50d|(50)d|750d, e|10d|(10)d| |Unstable
(reactive)|1|NA|NL|NL|NL|NL|NL|NL|NL|NL| |Water
reactive|3|H-2|5d, e|(5)d, e|NA|5d|(5)d|NA|1d|(1)d| |Water
reactive|2|H-3|50d, e|(50)d, e|(50)d, e|50d|(50)d|(50)d|10d|(10)d| |Water
reactive|1|NA|NL|NL|NL|NL|NL|NL|NL|NL| |For SI: 1 cubic foot = 0.02832 m3, 1 pound = 0.454 kg, 1 gallon = 3.785 L.
NA = Not Applicable, NL = Not Limited, UD = Unclassified Detonable.
a. For use of control areas, see Section 5003.8.3.
b. The aggregate quantity in use and storage shall not exceed the maximum allowance quantity for storage, including applicable increases.
c. For hazardous materials in Group B higher education laboratory occupancies, see Section 428 of the_California Building Code_ and Chapter 38.
d._ [SFM]__ In other than Group L occupancies, maximum allowable quantities shall be increased 100 percent in buildings equipped throughout with an automatic sprinkler system in_
_accordance with Section 903.3.1.1.

Frequently asked questions

When exactly can a vertical shaft remain unenclosed?

When each shaft opening is blocked at every floor by not less than 2 full inches (51 mm) of solid wood or equivalent construction to prevent initial passage of smoke and flame — per § 8-407. Alternatives such as sprinklers may be accepted by the enforcing agency.

Does installing sprinklers automatically let me remove area separation walls?

Not automatically — the CHBC allows sprinklers to be considered in lieu of area separations or enclosure, but acceptance is a case‑by‑case enforcing‑agency decision. See § 8-407, § 8-302.6, and § 8-402 for the framework.

What is the 15,000 sq ft rule I keep seeing?

§ 8-302.4 says a one‑story qualified historical building may have a floor area up to 15,000 sq ft unless otherwise permitted; Chapter 8-3 contains the full context and exceptions.

If my historic building is two stories and residential, are area separation walls required?

Residential occupancies of two stories or less may be exempt from area‑separation walls if they have a complete fire alarm and annunciation system and exiting conform to regular code — see § 8-302.4.

Who approves alternative solutions (sprinklers, other measures)?

The enforcing agency must approve alternatives; the CHBC repeatedly notes that sprinklers or other measures are considered on a case‑by‑case basis and may substitute for certain requirements. See § 8-407 and § 8-402.2.

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Related in the CHBC

What are maximum floor area and height limits for qualified historical buildings?

How are required occupancy separations treated for historic buildings?

Area, height and occupancy separation limits

California Historical Building Code