CHBC · California Historical Building Code

What are the minimum clear opening, dimensions and operability requirements for emergency escape/rescue windows and doors?

If your building is being regulated under the California Historical Building Code, each basement and every sleeping room below the fourth floor must have at least one openable emergency escape opening that opens to a public street/way/yard/exit court, provides at least 3.3 square feet of clear area, has at least an 18‑inch width or height, and can be opened from the inside without special tools (CHBC **§ 8-503**).

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

Basements and every sleeping room below the fourth floor in a qualified historical building must have at least one openable window or door approved for emergency escape that opens directly to a public street, public way, yard, or exit court. The opening must provide a minimum clear area of 3.3 square feet (0.31 m²) and must have a minimum width or height of 18 inches (457 mm). The opening must be operable from the inside to provide a full, clear opening without the use of special tools — these requirements are set by § 8-503 of the CHBC.

Most important: any required escape/rescue opening in a CHBC-covered historic building must be an openable unit giving at least 3.3 ft² of clear area, at least 18 in in one dimension, and must open to a public street/way/yard/exit court without special tools (see § 8-503).

Requirements in detail

Scope / where required

  • Required in: basements in dwelling units and every sleeping room below the fourth floor. § 8-503.
  • Must open directly to: a public street, public way, yard or exit court. § 8-503.

Minimum clear opening and dimensions (decision table)

Requirement Value Code Reference
Minimum net clear area 3.3 sq ft (0.31 m²) § 8-503
Minimum width or height (either dimension) 18 in (457 mm) § 8-503
Operability from inside (no special tools) Must provide full clear opening — operable from inside without special tools § 8-503
Where it must discharge Public street / public way / yard / exit court § 8-503

Notes:

  • The CHBC text uses “minimum clear area” and “minimum width or height dimension” — these are net clear opening requirements that must result from the normal operation of the window or door. § 8-503.
  • CHBC § 8-503 does not add other dimension constraints (for example, it does not specify a maximum sill height or the larger 5.7 ft² requirement used in the regular CBC/CRC). If you need those additional constraints for a non-historic project, see the regular code.

Operability and releases

  • The escape opening must be operable from the inside and must give a full, clear opening without requiring special tools. This means the occupant must be able to open/release any latch or device from inside without keys or unusual force. § 8-503.
  • CHBC § 8-503 does not detail requirements for burglar bars, opening-control devices, or exterior release devices — those topics are covered in other code parts (regular CBC/CRC or local fire code). For historic buildings, consult the enforcing agency where such devices are proposed.

Exceptions & special cases

  • The CHBC text of § 8-503 contains no express exceptions in the section text returned; it sets the historic-code minimums shown above. If you need to apply an alternative (because historical features would be threatened), CHBC’s alternative/variance provisions and the enforcing agency’s discretion may apply (see CHBC chapters on means of egress and historical alternatives).
  • The CHBC minimums are smaller than the regular code (for example, the California Building Code requires 5.7 ft² net clear area and 24 in × 20 in minimums in many cases). Do not conflate CHBC minima with the regular CBC/CRC requirements unless the project is not under CHBC scope. For reference, see CBC/CRC provisions (not CHBC) that show the larger dimensions.
  • Area wells, ladders/steps, and drainage are not specified in § 8-503. If your escape opening is below grade or has an area well, consult the regular code and the enforcing agency for required area-well dimensions and ladder/step rules (the CBC/CRC include those rules).

Common mistakes

  • Mixing codes: assuming the CHBC requires the 5.7 ft² / 24 in × 20 in residential dimensions — that is the regular CBC/CRC, not the CHBC § 8-503 minimums. Check whether the CHBC applies to your building before using regular-code numbers.
  • Measuring overall frame size instead of net clear opening: the CHBC minimums apply to the clear opening produced by normal operation (the actual passage area), not the glass lite or outer frame dimension. § 8-503.
  • Forgetting discharge requirement: the opening must open directly to a public street, public way, yard or exit court — an opening to a small enclosed court that does not connect to a public way may not comply. § 8-503.
  • Adding bars or grills that require a key or tool to release: CHBC requires the opening be operable from the inside without special tools. If you propose bars or grills, the release must meet the “no special tools” operability from inside (and local fire code may require an exterior release for firefighters). § 8-503 (see related fire code rules for security devices).

Worked example — concrete scenario

Scenario: a basement sleeping room in a qualified historic dwelling proposes an operable casement window that opens to a rear yard.

  • Measured clear opening when the window is fully open: 24 in (width) × 24 in (height) → 576 in² = 4.0 ft².
  • CHBC check:
    • Is the clear area ≥ 3.3 ft²? Yes — 4.0 ft² > 3.3 ft² (meets § 8-503).
    • Is at least one dimension ≥ 18 in? Yes — both are 24 in, so OK. § 8-503.
    • Does it open directly to a yard that is a public way/yard/exit court? If the yard connects to a public way per local definition, yes — otherwise you must confirm the yard qualifies. § 8-503.
    • Is the window operable from inside without special tools? If the casement crank or latch can be operated from the inside without keys/special tools, yes — otherwise modify hardware. § 8-503.

If the window were only 20 in × 18 in (360 in² = 2.5 ft²), it would fail the 3.3 ft² area requirement even though one dimension meets 18 in. § 8-503.

Related provisions (CHBC and nearby references)

  • Means of egress purpose and scope: § 8-501.
  • General egress allowances and enforcing-agency discretion: § 8-502.
  • Railing and guardrail historic allowance (often relevant around egress paths): § 8-504.
  • CHBC accessibility alternatives / historic exceptions: § 8-601 (chapter on accessibility) — consult when historic features conflict with regular code.
  • For comparison (regular code requirements and area-well rules—not CHBC): CBC/CRC emergency escape rules (CBC §1031 / CRC R319) show larger minimums and area-well provisions; consult these only if CHBC does not apply to your project or the enforcing agency requires regular-code compliance.

Code references

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

  • CHBC § 12-3 High relevance — show source text

    Such bars, grills, grates or any similar devices shall be equipped with an approved exterior release device for use by the fire department only when required by the authority having jurisdiction.

    Where security bars (burglar bars) are installed on emergency egress and rescue windows or doors, on or after July 1, 2000, such devices shall comply with California Building Standards Code, Part 12, Chapter 12-3 and other applicable provisions of Part 2.

    Exception: Group R-1 occupancies provided with a monitored fire sprinkler system in accordance with Section 903.2.8 and designed in accordance with NFPA 13 may have openable windows permanently restricted to a maximum 4-inch (102 mm) open position.

    1031.2.2 Maintenance. Fire escape stairways and balconies shall be kept clear and unobstructed at all times and shall be main- tained in good working order.

    1031.2.3 Examination. Fire escape stairways and balconies shall be examined for structural adequacy and safety by a registered design professional or other person acceptable to the fire code official every 5 years. The examination shall determine whether the fire escape stairways and balconies can support the dead load plus a live load of not less than 100 pounds per square foot (4.78 kN/m). An inspection report shall be submitted to the fire code official after such examination.

    1031.3 Emergency escape and rescue openings. Emergency escape and rescue openings shall comply with Sections 1031.3.1 through 1031.3.3.

    1031.3.1 Minimum size. Emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.53 m [2] ).

    Exception: The minimum net clear opening for grade-floor emergency escape and rescue openings shall be 5 square feet (0.46 m [2] ).

    1031.3.2 Minimum dimensions. The minimum net clear opening height dimension shall be 24 inches (610 mm). The minimum net clear opening width dimension shall be 20 inches (508 mm). The net clear opening dimensions shall be the result of normal operation of the opening.

    1031.3.3 Maximum height from floor. Emergency escape and rescue openings shall have the bottom of the clear opening not greater than 44 inches (1118 mm) measured from the floor.

    1031.4 Emergency escape and rescue doors. Where a door is provided as the required emergency escape and rescue opening, it shall be a swinging door or a sliding door.

    1031.5 Area wells. An emergency escape and rescue opening with the bottom of the clear opening below the adjacent grade shall be provided with an area well in accordance with Sections 1031.5.1 through 1031.5.3.

    10-60 2025 CALIFORNIA BUILDING CODE

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    MEANS OF EGRESS

    1031.5.1 Minimum size. The minimum horizontal area of the area well shall be 9 square feet (0.84 m [2] ), with a horizontal projection and width of not less than 36 inches (914 mm). The area well shall allow the emergency escape and rescue opening to be fully opened.

    Exception: The ladder or steps required by Section 1031.5.2 shall be permitted to encroach not more than 6 inches (152 mm) into the required dimensions of the area well.

  • CHBC § 0.46 High relevance — show source text

    Exception: The minimum net clear opening for grade-floor emergency escape and rescue openings shall be 5 square feet (0.46 m [2] ).

    1031.3.2 Minimum dimensions. The minimum net clear opening height dimension shall be 24 inches (610 mm). The minimum net clear opening width dimension shall be 20 inches (508 mm). The net clear opening dimensions shall be the result of normal operation of the opening.

    1031.3.3 Maximum height from floor. Emergency escape and rescue openings shall have the bottom of the clear opening not greater than 44 inches (1118 mm) measured from the floor.

    1031.4 Emergency escape and rescue doors. Where a door is provided as the required emergency escape and rescue opening, it shall be a swinging door or a sliding door.

    1031.5 Area wells. An emergency escape and rescue opening with the bottom of the clear opening below the adjacent grade shall be provided with an area well in accordance with Sections 1031.5.1 through 1031.5.3.

    10-60 2025 CALIFORNIA BUILDING CODE

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    MEANS OF EGRESS

    1031.5.1 Minimum size. The minimum horizontal area of the area well shall be 9 square feet (0.84 m [2] ), with a horizontal projection and width of not less than 36 inches (914 mm). The area well shall allow the emergency escape and rescue opening to be fully opened.

    Exception: The ladder or steps required by Section 1031.5.2 shall be permitted to encroach not more than 6 inches (152 mm) into the required dimensions of the area well.

    1031.5.2 Ladders or steps. Area wells with a vertical depth of more than 44 inches (1118 mm) shall be equipped with an approved permanently affixed ladder or steps. The ladder or steps shall not be obstructed by the emergency escape and rescue opening when the window or door is in the open position. Ladders or steps required by this section shall not be required to comply with Section 1011.

    1031.5.2.1 Ladders. Ladders or rungs shall have an inside width of at least 12 inches (305 mm), shall project at least 3 inches (76 mm) from the wall and shall be spaced not more than 18 inches (457 mm) on center (o.c.) vertically for the full height of the area well.

    1031.5.2.2 Steps. Steps shall have an inside width of not less than 12 inches (305 mm), shall have treads greater than 5 inches (127 mm) in depth and a riser height not greater than 18 inches (457 mm) for the full height of the area well.

    1031.5.3 Drainage. Area wells shall be designed for proper drainage by connecting to the building’s foundation drainage system required by Section 1805.

    Exception: A drainage system for area wells is not required where the foundation is on well-drained soil or sand-gravel mixture soils in accordance with the United Soil Classification System, Group I Soils, in accordance with Section 1803.5.1.

  • CHBC § 8-503 High relevance — show source text

    2025 CALIFORNIA HISTORICAL BUILDING CODE 9

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

    MEANS OF EGRESS

    SECTION 8-503 — ESCAPE OR RESCUE WINDOWS AND DOORS

    Basements in dwelling units and every sleeping room below the fourth floor shall have at least one openable window or door approved for emergency escape which shall open directly into a public street, public way, yard or exit court. Escape or rescue windows or doors shall have a minimum clear area of 3.3 square feet (0.31 m [2] ) and a minimum width or height dimension of 18 inches (457 mm) and be operable from the inside to provide a full, clear opening without the use of special tools.

    SECTION 8-504 — RAILINGS AND GUARDRAILS

    The height of railings and guard railings and the spacing of balusters may continue in their historical height and spacing unless a distinct hazard has been identified or created by a change in use or occupancy.

    10 2025 CALIFORNIA HISTORICAL BUILDING CODE

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    8-6 ACCESSIBILITY

    SECTION 8-601 — PURPOSE, INTENT AND 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 qualified 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.

    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 a 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.

    SECTION 8-603 — ALTERNATIVES

  • CHBC § 33.3 High relevance — show source text

    Stairway openings in such balconies shall not be less than 22 inches by 44 inches (559 by 1118 mm). The balustrade of each balcony shall not be less than 36 inches (914 mm) high with not more than 9 inches (287 mm) between balusters. 6. Fire escapes shall extend to the roof or provide an approved gooseneck ladder between the top floor landing and the roof when serving buildings four or more stories in height having roofs with less than 4 units vertical in 12 units horizontal (33.3 percent slope). Fire escape ladders shall be designed and connected to the building to withstand a horizontal force of 100 pounds (445 N) placed anywhere on the rung. All ladders shall be at least 15 inches (381 mm) wide, located within 12 inches (305 mm) of the building. Ladder rungs shall be [3] / 4 inch (19.1 mm) in diameter and shall be located 12 inches (305 mm) on center. Openings for roof access ladders through cornices and similar projections shall have minimum dimensions of 30 inches by 33 inches (762 by 838 mm). The length of fire escapes and exit ladder devices shall be limited to that approved by the building official based on products listed by a recognized testing laboratory. 7. The lowest balcony shall not be more than 18 feet (5486 mm) from the ground. Fire escapes shall extend to the ground or be provided with counterbalanced stairs reaching to the ground. 8. Fire escapes shall not take the place of stairways required by the codes under which the building was constructed. 9. Fire escapes shall be kept clear and unobstructed at all times and maintained in good working order.

    2025 CALIFORNIA HISTORICAL BUILDING CODE 9

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

    MEANS OF EGRESS

    SECTION 8-503 — ESCAPE OR RESCUE WINDOWS AND DOORS

    Basements in dwelling units and every sleeping room below the fourth floor shall have at least one openable window or door approved for emergency escape which shall open directly into a public street, public way, yard or exit court. Escape or rescue windows or doors shall have a minimum clear area of 3.3 square feet (0.31 m [2] ) and a minimum width or height dimension of 18 inches (457 mm) and be operable from the inside to provide a full, clear opening without the use of special tools.

    SECTION 8-504 — RAILINGS AND GUARDRAILS

    The height of railings and guard railings and the spacing of balusters may continue in their historical height and spacing unless a distinct hazard has been identified or created by a change in use or occupancy.

    10 2025 CALIFORNIA HISTORICAL BUILDING CODE

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    8-6 ACCESSIBILITY

    SECTION 8-601 — PURPOSE, INTENT AND 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 qualified historical buildings or properties. These regulations require enforcing agencies to accept alternatives to regular code when dealing with qualified historical buildings or properties.

  • CHBC § 1031.3 High relevance — show source text

    (a) Where the California Building Code requires openable burglar bars for emergency escape or rescue, or

    (b) On mobile homes, manufactured homes or multi-unit manufactured housing unless at least one window or door to the exterior in each bedroom is openable for emergency escape or rescue.

    [BE] 1031.3 Emergency escape and rescue openings. Emergency escape and rescue openings shall comply with Sections 1031.3.1 through 1031.3.3.

    [BE] 1031.3.1 Minimum size. Emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.53 m [2] ). Exception: The minimum net clear opening for grade-floor emergency escape and rescue openings shall be 5 square feet (0.46 m [2] ).

    [BE] 1031.3.2 Minimum dimensions. The minimum net clear opening height dimension shall be 24 inches (610 mm). The minimum net clear opening width dimension shall be 20 inches (508 mm). The net clear opening dimensions shall be the result of normal operation of the opening.

    [BE] 1031.3.3 Maximum height from floor. Emergency escape and rescue openings shall have the bottom of the clear opening not greater than 44 inches (1118 mm) measured from the floor.

    [BE] 1031.4 Emergency escape and rescue doors. Where a door is provided as the required emergency escape and rescue opening, it shall be a swinging door or a sliding door.

    [BE] 1031.5 Area wells. An emergency escape and rescue opening with the bottom of the clear opening below the adjacent grade shall be provided with an area well in accordance with Sections 1031.5.1 through 1031.5.3.

    [BE] 1031.5.1 Minimum size. The minimum horizontal area of the area well shall be 9 square feet (0.84 m [2] ), with a horizontal projection and width of not less than 36 inches (914 mm). The area well shall allow the emergency escape and rescue opening to be fully opened.

    Exception: The ladder or steps required by Section 1031.5.2 shall be permitted to encroach not more than 6 inches (152 mm) into the required dimensions of the area well.

    [BE] 1031.5.2 Ladders or steps. Area wells with a vertical depth of more than 44 inches (1118 mm) shall be equipped with an approved permanently affixed ladder or steps. The ladder or steps shall not be obstructed by the emergency escape and rescue opening when the window or door is in the open position. Ladders or steps required by this section shall not be required to comply with Section 1011.

    [BE] 1031.5.2.1 Ladders. Ladders or rungs shall have an inside width of at least 12 inches (305 mm), shall project at least 3 inches (76 mm) from the wall and shall be spaced not more than 18 inches (457 mm) on center (o.c.) vertically for the full height of the area well.

    [BE] 1031.5.2.2 Steps. Steps shall have an inside width of not less than 12 inches (305 mm), shall have treads greater than 5 inches (127 mm) in depth and a riser height not greater than 18 inches (457 mm) for the full height of the area well.

  • CHBC § 18.6 High relevance — show source text

    R319.1 Emergency escape and rescue opening required. Basements, habitable attics, the room to which a sleeping loft is open, and every sleeping room shall have not less than one operable emergency escape and rescue opening. Where basements contain one or more sleeping rooms, an emergency escape and rescue opening shall be required in each sleeping room. Emergency escape and rescue openings shall open directly into a public way, or to a yard or court that opens to a public way.

    Exceptions [SFM]: 1. Basements with a ceiling height of less than 80 inches (2032 mm) shall not be required to have emergency escape and rescue openings. 2. Emergency escape and rescue openings are not required from basements or sleeping rooms that have an exit door or exit access door that opens directly into a public way or to a yard, court or exterior egress balcony that opens to a public way. 3. Basements without habitable spaces and having not more than 200 square feet (18.6 m [2] ) in floor area shall not be required to have emergency escape and rescue openings. 4. Storm shelters are not required to comply with this section where the shelter is constructed in accordance with ICC 500. 5. Where the dwelling unit or townhouse unit is equipped with an automatic sprinkler system installed in accordance with Section R309, sleeping rooms in basements shall not be required to have emergency escape and rescue openings provided that the basement has one of the following: 5.1. One means of egress complying with Section R318 and one emergency escape and rescue opening. 5.2. Two means of egress complying with Section R318.

    R319.1.1 Operational constraints and opening control devices. Emergency escape and rescue openings shall be maintained free of any obstructions other than those allowed by this section and shall be operational from the inside of the room without the use of keys, tools or special knowledge. Window opening control devices and fall prevention devices complying with ASTM F2090 shall be permitted for use on windows serving as a required emergency escape and rescue opening and shall be not more than 70 inches (178 cm) above the finished floor. The release mechanism shall be maintained operable at all times.

    Such bars, grills, grates or any similar devices shall be equipped with an approved exterior release device for use by the fire department only when required by the authority having jurisdiction.

    Where security bars (burglar bars) are installed on emergency egress and rescue windows or doors, on or after July 1, 2000, such devices shall comply with California Building Standards Code, Part 12, Chapter 12-3 and other applicable provisions of this code.

    R319.2 Emergency escape and rescue openings. Emergency escape and rescue openings shall have minimum dimensions in accordance with Sections R319.2.1 through R319.2.4.

    R319.2.1 Minimum size. Emergency escape and rescue openings shall have a net clear opening of not less than 5.7 square feet (0.530 m [2] ).

    Exception: The minimum net clear opening for grade-floor emergency escape and rescue openings shall be 5 square feet (0.465 m [2] ).

    R319.2.2 Minimum dimensions. The minimum net clear opening height dimension shall be 24 inches (610 mm). The minimum net clear opening width dimension shall be 20 inches (508 mm). The net clear opening dimensions shall be the result of normal operation of the opening.

  • CHBC § 8-5 High relevance — show source text

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

    8-5 MEANS OF EGRESS

    SECTION 8-501 — PURPOSE, INTENT AND SCOPE

    8-501.1 Purpose. The purpose of this chapter is to establish minimum means of egress regulations for qualified historical buildings or properties. The CHBC requires enforcing agencies to accept reasonably equivalent alternatives to the means of egress requirements in the regular code.

    8-501.2 Intent. The intent of these regulations is to provide an adequate means of egress.

    8-501.3 Scope. Every qualified historical building or portion thereof shall be provided with exits as required by the CHBC when required by the provisions of Section 8-102.

    SECTION 8-502 — GENERAL

    8-502.1 General. The enforcing agency shall grant reasonable exceptions to the specific provisions of applicable egress regulations where such exceptions will not adversely affect life safety.

    8-502.2. Existing door openings and corridor widths of less than dimensions required by regular code shall be permitted where there is sufficient width and height for the occupants to pass through the opening or traverse the exit.

    8-502.3 Stairs. Existing stairs having risers and treads or width at variance with the regular code are allowed if determined by the enforcing agency to not constitute a distinct hazard. Handrails with nonconforming grip size or extensions are allowed if determined by the enforcing agency to not constitute a distinct hazard.

    8-502.4 Main entry doors. The front or main entry doors need not be rehung to swing in the direction of exit travel, provided other means or conditions of exiting, as necessary to serve the total occupant load, are provided.

    8-502.5 Existing fire escapes. Existing previously approved fire escapes and fire escape ladders shall be acceptable as one of the required means of egress, provided they extend to the ground and are easily negotiated, adequately signed and in good working order. Access shall be by an opening having a minimum width of 29 inches (737 mm) when open with a sill no more than 30 inches (762 mm) above the adjacent floor, landing or approved step.

    8-502.6 New fire escapes and fire escape ladders. New fire escapes and fire escape ladders which comply with this section shall be acceptable as one of the required means of egress. New fire escapes and new fire escape ladders shall comply with the following:

    1. Access from a corridor shall not be through an intervening room.
    2. All openings within 10 feet (3048 mm) shall be protected by three-fourths-hour fire assemblies. When located within a recess or vestibule, adjacent enclosure walls shall be of not less than one-hour fire-resistive construction.
    3. Egress from the building shall be by a clear opening having a minimum dimension of not less than 29 inches (737 mm). Such openings shall be openable from the inside without the use of a key or special knowledge or effort. The sill of an opening giving access shall not be more than 30 inches (737 mm) above the floor, step or landing of the building or balcony.
    4. Fire escape stairways and balconies shall support the dead load plus a live load of not less than 100 pounds per square foot (4.79 kN/m [2] ) and shall be provided with a top and intermediate handrail on each side. The pitch of the stairway shall not exceed 72 degrees with a minimum width of 18 inches (457 mm).
  • CHBC § 1.1 High relevance — show source text

    Exception: The building need not be made to comply with Chapter 16 A of the California Building Code unless required by Section 506 A .5.

    506 A .1.1 Change in function . A change in function shall require compliance with all the functional requirements for new construc- tion in the California Building Code, including requirements in California Building Code Section 1224. Compliance shall be only as necessary to meet the specific provisions and is not intended to require the entire building be brought into compliance.

    Exception: Minimum room clearances, areas and dimensions may meet the requirements of the 2001 California Building Code for existing rooms re-used for a similar purpose, subject to the approval of OSHPD.

    506 A .2 Certificate of occupancy. A certificate of occupancy shall be issued where it has been determined that the requirements for the new occupancy classification have been met.

    506 A .3 Stairways. An existing stairway shall not be required to comply with the requirements of Section 1011 of the California Build- ing Code where the existing space and construction does not allow a reduction in pitch or slope.

    506 A .4 Existing emergency escape and rescue openings. Where a change of occupancy would require an emergency escape and rescue opening in accordance with Section 1031.1 of the California Building Code, operable windows serving as the emergency escape and rescue opening shall comply with the following:

    1. An existing operable window shall provide a minimum net clear opening of 4 square feet (0.38 m [2] ) with a minimum net clear opening height of 22 inches (559 mm) and a minimum net clear opening width of 20 inches (508 mm).
    2. A replacement window where such window complies with both of the following: 2.1. The replacement window meets the size requirements in Item 1. 2.2. The replacement window is the manufacturer’s largest standard size window that will fit within the existing frame or existing rough opening. The replacement window shall be permitted to be of the same operating style as the existing window or a style that provides for an equal or greater window opening area than the existing window.

    506 A .5 Structural. Any building undergoing a change of occupancy shall satisfy the requirements of this section.

    506 A .5.1 Live loads. Structural elements carrying tributary live loads from an area with a change of occupancy shall satisfy the requirements of Section 1607 A of the California Building Code . Design live loads for areas of new occupancy shall be based on Section 1607 A of the California Building Code . Design live loads for other areas shall be permitted to use previously approved design live loads.

    Exception: Structural elements whose demand-capacity ratio considering the change of occupancy is not more than 5 percent greater than the demand-capacity ratio based on previously approved live loads need not comply with this section.

    506 A .5.2 Snow and wind loads. Where a change of occupancy results in a structure being assigned to a higher risk category, the structure shall satisfy the requirements of Sections 1608 A and 1609 A of the California Building Code for the new risk category.

    Exception: Where the area of the new occupancy is less than 10 percent of the building area, compliance with this section is not required. The cumulative effect of occupancy changes over time shall be considered.

  • CHBC § 10-62 High relevance — show source text

    10-62 2025 CALIFORNIA FIRE CODE

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    MEANS OF EGRESS

    (5) Written directions and illustrations on the operation of the emergency escape release mechanisms. These directions shall include a warning that the mechanisms be tested on a monthly basis.

    (b) The textual information required by this section shall be printed in a minimum 12-point nondecorative lettering providing a sharp contrast to the background.

    (c) Graphical information required by this section shall be of sufficient size to clearly illustrate the intended actions.

    [California Code of Regulations, Title 19, Division 1, §4.4] Warning Information Location.

    When placed on burglar bar packaging, the information required by California Code of Regulations, Title 19, Division 1, Section 4.3 shall be conspicuously located and shall not be covered or made illegible by product advertising not required by Section 4.3.

    [California Code of Regulations, Title 19, Division 1, §4.5(a)] Contractor or Installer Disclosures.

    Any contractor or installer of burglar bars shall provide the owner of the residential dwelling the warning information required pursu- ant to California Code of Regulations, Title 19, Division 1, Section 4.3 prior to installing burglar bars.

    [California Code of Regulations, Title 19, Division 1, §4.6(a) and (b)] Prohibited Installations.

    No person shall install for profit unopenable burglar bars on a residential dwelling:

    (a) Where the California Building Code requires openable burglar bars for emergency escape or rescue, or

    (b) On mobile homes, manufactured homes or multi-unit manufactured housing unless at least one window or door to the exterior in each bedroom is openable for emergency escape or rescue.

    [BE] 1031.3 Emergency escape and rescue openings. Emergency escape and rescue openings shall comply with Sections 1031.3.1 through 1031.3.3.

    [BE] 1031.3.1 Minimum size. Emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.53 m [2] ). Exception: The minimum net clear opening for grade-floor emergency escape and rescue openings shall be 5 square feet (0.46 m [2] ).

    [BE] 1031.3.2 Minimum dimensions. The minimum net clear opening height dimension shall be 24 inches (610 mm). The minimum net clear opening width dimension shall be 20 inches (508 mm). The net clear opening dimensions shall be the result of normal operation of the opening.

    [BE] 1031.3.3 Maximum height from floor. Emergency escape and rescue openings shall have the bottom of the clear opening not greater than 44 inches (1118 mm) measured from the floor.

    [BE] 1031.4 Emergency escape and rescue doors. Where a door is provided as the required emergency escape and rescue opening, it shall be a swinging door or a sliding door.

    [BE] 1031.5 Area wells. An emergency escape and rescue opening with the bottom of the clear opening below the adjacent grade shall be provided with an area well in accordance with Sections 1031.5.1 through 1031.5.3.

  • CHBC § 2.1. High relevance — show source text

    The window is operable. 2. One of the following applies: 2.1. The window replacement includes replacement of the sash and frame. 2.2. The window replacement includes the sash only where the existing frame remains. 3. One of the following applies: 3.1. In Group R-2 or R-3 buildings containing dwelling or sleeping units, the bottom of the clear opening of the window opening is at a height less than 36 inches (915 mm) above the finished floor. 3.2. In one- and two-family dwellings and townhouses regulated by the California Residential Code, the bottom of the clear opening of the window opening is at a height less than 24 inches (610 mm) above the finished floor. 4. The window will permit openings that will allow passage of a 4-inch-diameter (102 mm) sphere when the window is in its largest opened position. 5. The vertical distance from the bottom of the clear opening of the window opening to the finished grade or other surface below, on the exterior of the building, is greater than 72 inches (1829 mm).

    Exception: Operable windows where the bottom of the clear opening of the window opening is located more than 75 feet (22 860 mm) above the finished grade or other surface below, on the exterior of the room, space or building, and that are provided with window fall prevention devices that comply with ASTM F2006.

    505.3 Replacement window emergency escape and rescue openings. Where windows are required to provide emergency escape and rescue openings in Group R-2 and R-3 occupancies and one- and two-family dwellings and townhouses regulated by the California Residential Code, replacement windows shall be exempt from the requirements of Section 1031.3 of the California Building Code and Section 319.2 of the California Residential Code, provided that the replacement window meets the following conditions:

    1. The replacement window is the manufacturer’s largest standard size window that will fit within the existing frame or existing rough opening. The replacement window shall be permitted to be of the same operating style as the existing window or a style that provides for an equal or greater window opening area than the existing window.
    2. Where the replacement of the window is part of a change of occupancy, it shall comply with Section 1011.5.6.

    505.3.1 Control devices. Window opening control devices or fall prevention devices complying with ASTM F2090 shall be permitted for use on windows required to provide emergency escape and rescue openings. After operation to release the control device allowing the window to fully open, the control device shall not reduce the net clear opening area of the window unit. Emergency escape and rescue openings shall be operational from the inside of the room without the use of keys or tools.

    5-8 2025 CALIFORNIA EXISTING BUILDING CODE

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

    PRESCRIPTIVE COMPLIANCE METHOD

    505.4 Bars, grilles, covers or screens. Bars, grilles, covers, screens or similar devices are permitted to be placed over emergency escape and rescue openings, bulkhead enclosure or window wells that serve such openings, provided all of the following conditions are met:

  • CHBC § 12.7 High relevance — show source text

    1. Any stairway replacing an existing stairway within a space where the pitch or slope cannot be reduced because of existing construction shall not be required to comply with the maximum riser height and minimum tread depth requirements.

    2. Existing corridor walls constructed on both sides of wood lath and plaster in good condition or [1] / 2 -inch-thick (12.7 mm) gypsum wallboard shall be permitted. Such walls shall either terminate at the underside of a ceiling of equivalent construction or extend to the underside of the floor or roof next above.

    3. Existing corridor doorways, transoms and other corridor openings shall comply with the requirements in Sections 804.7.1, 804.7.2 and 804.7.3.

    4. Existing dead-end corridors shall comply with the requirements in Section 804.8.

    5. An operable window complying with Section 1011.5.6 shall be accepted as an emergency escape and rescue opening.

    6. In Group R-2.1 and I-2 facilities, required guards enclosing the occupiable roof areas shall be permitted to be greater than 48 inches (1219 mm) above the surface of the occupiable roof where the occupants, because of clinical needs, require restraint or containment as part of a function of a psychiatric or cognitive treatment area.

    1011.5.2 Means of egress for change of use to an equal or lower-hazard category. Where a change of occupancy classification is made to an equal or lesser-hazard category (higher number) as shown in Table 1011.5, existing elements of the means of egress shall comply with the requirements of Section 905 for the new occupancy classification. Newly constructed or configured means of egress shall comply with the requirements of Chapter 10 of the California Building Code .

    Exceptions:

    1. Any stairway replacing an existing stairway within a space where the pitch or slope cannot be reduced shall not be required to comply with the maximum riser height and minimum tread depth requirements.
    2. In Group R-2.1 and I-2 facilities, required guards enclosing the occupiable roof areas shall be permitted to be greater than 48 inches (1219 mm) above the surface of the occupiable roof where the occupants, because of clinical needs, require restraint or containment as part of a function of a psychiatric or cognitive treatment area.

    1011.5.3 Egress capacity. Egress capacity shall meet or exceed the occupant load as specified in the California Building Code for the new occupancy.

    1011.5.4 Handrails. Existing stairways shall comply with the handrail requirements of Section 804.13.

    1011.5.5 Guards. Existing guards shall comply with the requirements in Section 804.12.

    1011.5.6 Existing emergency escape and rescue openings. Where a change of occupancy would require an emergency escape and rescue opening in accordance with Section 1031 of the California Building Code, operable windows serving as the emergency escape and rescue opening shall comply with the following:

    1. An existing operable window shall provide a minimum net clear opening of 4 square feet (0.38 m [2] ) with a minimum net clear opening height of 22 inches (559 mm) and a minimum net clear opening width of 20 inches (508 mm).
    2. A replacement window where such window complies with both of the following: 2.1. The replacement window meets the size requirements in Item 1. 2.2. The replacement window is the manufacturer’s largest standard size window that will fit within the existing frame or existing rough opening.

Frequently asked questions

Who must follow CHBC § 8-503 instead of the regular code?

Qualified historical buildings/properties that are being regulated under the CHBC may use the CHBC provisions; whether CHBC applies depends on building designation and the enforcing agency. See CHBC scope and definitions in the means-of-egress chapter.

If my historic window is smaller than 3.3 ft², can I keep it?

Not as a required emergency escape in a basement or sleeping room under CHBC § 8-503 — the opening must meet the 3.3 ft² / 18 in minimums. If a historic feature would be threatened, discuss alternatives with the enforcing agency under CHBC alternatives provisions.

Does § 8-503 set a maximum sill height above the floor?

No — § 8-503 (as returned) does not specify a maximum sill height. The regular CBC/CRC include a maximum sill height requirement; consult the enforcing agency about which rule applies.

Can bars or burglar grilles be installed over the required opening?

The CHBC requires the opening be operable from the inside without special tools. If bars/grilles are used, their release must allow operation from the inside without special tools; local fire code may require an exterior release for first responders. Consult the enforcing agency and applicable fire code rules.

If the opening is below grade, does CHBC require an area well?

§ 8-503 does not address area wells. Area-well size and ladder/step requirements are covered in the regular CBC/CRC; confirm with the enforcing agency whether those regular-code area-well provisions apply to your historic project.

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