CHBC · California Historical Building Code

What escape or rescue window and door requirements apply to historic buildings?

If you have a historic dwelling basement or a sleeping room below the fourth floor, CHBC **§ 8-503** requires at least one openable escape window or door that opens to a public street/way/yard/exit court, provides a clear opening of at least **3.3 square feet**, has at least one dimension **18 inches** or more, and is operable from the inside without special tools .

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The California Historical Building Code requires that basements in dwelling units and every sleeping room below the fourth floor 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), have a minimum width or height of 18 inches (457 mm), and be operable from the inside to provide a full, clear opening without the use of special tools (see § 8-503) .

If a historic dwelling has a basement or any sleeping room below the fourth floor, it must have at least one inside-operable escape opening that gives at least 3.3 ft² and at least 18 in in one dimension — and it must open to the outdoors or a yard/exit court (CHBC § 8-503) .

Requirements in detail

Which spaces are covered

  • Basements in dwelling units (any basement that is part of a dwelling). § 8-503 requires at least one escape opening in these spaces.
  • Every sleeping room below the fourth floor must also have at least one such opening. § 8-503 is the controlling CHBC provision.

What the opening must be

  • The opening must be an openable window or door approved for emergency escape and must open directly to a public street, public way, yard or exit court. § 8-503
  • It must be operable from the inside and provide a full, clear opening without the use of special tools (no padlocks or permanently fixed burglar bars that require special tools). § 8-503

Key dimensions and thresholds (decision table)

Requirement Value (primary units) Value (metric) Code Reference
Minimum clear opening area 3.3 ft² 0.31 m² § 8-503
Minimum width OR height 18 in 457 mm § 8-503
Operability Must open from inside to give a full, clear opening without special tools — § 8-503
Discharge point Must open directly to a public street / public way / yard / exit court — § 8-503

Notes on the table: the CHBC text states the area and the single-dimension minimum and the operability requirement; it does not add other dimensional limits that some other codes include (see Exceptions & special cases below) .

Exceptions & special cases

  • The CHBC text of § 8-503 itself states the basic requirements above and does not list any exceptions in the provision text returned by the files. If you need a CHBC exception explicitly stated, § 8-503 as retrieved does not provide one.
  • By contrast, the regular California Building Code and Residential Code include other options, larger minimums, or exceptions (for example, CBC/CRC emergency opening dimensions and sill-height limits appear elsewhere in Part 2 documents). If a project is required to comply with the regular code (for example, because of a change of occupancy or other trigger), those higher/alternate requirements may apply — but those are not set by § 8-503 (see CBC/CRC excerpts in the file set for comparison) .
  • If the historic building owner or the enforcing agency elects to apply the regular code instead of the CHBC, or if an alteration triggers regular-code application, the larger net-clear opening values and other conditions in CBC/CRC may apply (consult the applicable regular code sections and the enforcing agency). The CHBC text retrieved here governs where the CHBC is invoked.

Common mistakes

  • Assuming the sill-height/maximum bottom-of-opening limits from the Residential or Building Code (for example, the 44 in maximum sill height in regular code) automatically apply under the CHBC. § 8-503 (CHBC) as retrieved does not include a maximum sill-height requirement — it only prescribes area and one-dimension minimum and the operability/discharge requirement. Do not mix in regular-code numbers unless a local official has required regular-code compliance.
  • Miscalculating net clear opening area by using nominal frame sizes instead of the actual clear/usable opening (measure the clear, unobstructed opening produced by normal operation). § 8-503 requires a clear area of 3.3 ft².
  • Installing security bars, grilles or covers that are not releasable from the inside without special tools or that reduce the net clear opening. § 8-503 requires the opening be operable and give a full clear opening from the inside without special tools. If you install bars, make sure they comply with release requirements and do not reduce clear area.
  • Using the CHBC minimum (3.3 ft²) when a project’s scope or change-of-occupancy forces application of the regular code; always confirm which code governs with the enforcing agency. The CHBC is an alternative path for qualified historic buildings; triggers can force regular-code application.

Worked example — concrete scenario

Scenario: A historic duplex has a basement sleeping room that opens to a small yard. The owner proposes to keep the historic window frame but replace the sash.

  • CHBC rule: the opening must provide at least 3.3 ft² clear area and at least 18 in in width or height and be operable from the inside without special tools (CHBC § 8-503) .
  • Existing clear opening (when window is fully opened): 20 inches wide × 30 inches high = 600 in² = 600 / 144 = 4.17 ft². That exceeds 3.3 ft² and both dimensions are ≥ 18 in, so the opening meets the CHBC dimensional requirements.
  • Confirm operability: the new sash must open fully from inside without special tools. If the owner plans security bars, those bars must not reduce the net clear opening and must be releasable from inside without special tools — otherwise the opening would fail the operability requirement in § 8-503.
  • Confirm discharge: the window opens directly to the yard (acceptable discharge per § 8-503) .

Conclusion: With a 20" × 30" clear opening that opens to the yard and an inside-release sash, the opening complies with § 8-503 in the CHBC.

Related provisions

  • § 8-303.6 — Light and ventilation: CHBC cross-references § 8-503 for openable sleeping-room windows in residential occupancies.
  • § 8-504 — Railings and guardrails: related CHBC provision for historic railings (useful when exterior escape paths involve guardrails).
  • CHBC Part heading: Chapter 8-5, Section 8-503 — Means of egress, Escape or Rescue Windows and Doors (table of contents and location).

If you need comparisons to the regular (non‑historical) code requirements (CBC/CRC/CFC) for replacement windows, sill heights, or area-well rules, those texts appear in the standard code files in the project file set — but remember CHBC § 8-503 is the controlling CHBC rule unless the enforcing agency requires regular-code compliance for the work in question.

Code references

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

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

    2025 CALIFORNIA HISTORICAL BUILDING CODE 9

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    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.

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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 § 4.2.2 High relevance — show source text

    R319.4.2.2 Steps. Steps shall have an inside width of not less than 12 inches (305 mm), a minimum tread depth of 5 inches (127 mm) and a maximum riser height of 18 inches (457 mm) for the full height of the area well.

    R319.4.3 Drainage. Area wells shall be designed for proper drainage by connecting to the building’s foundation drainage system required by Section R405.1.

    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, as detailed in Table R401.4.1(2).

    R319.4.4 Bars, grilles, covers and screens. Where bars, grilles, covers, screens or similar devices are placed over emergency escape and rescue openings, bulkhead enclosures or area wells that serve such openings, the minimum net clear opening size shall comply with Sections R319.2 through R319.2.2 and R319.4.1. Such devices shall be releasable or removable from the inside without the use of a key or tool or force greater than that required for the normal operation of the escape and rescue opening. 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.

    R319.5 Replacement windows for emergency escape and rescue openings. Replacement for emergency escape and rescue openings installed in buildings meeting the scope of this code shall be exempt from Sections R319.2 and R319.4.4, 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. The replacement window is not part of a change of occupancy.

    R319.5.1 Window opening control device and fall protection device height. Window opening control devices or fall protection devices shall be located at a height in accordance with Section R319.1.1 or at as low a height as the device can be installed within the existing clear opening.

    R319.6 Dwelling additions. Where dwelling unit additions contain sleeping rooms, an emergency escape and rescue opening shall be provided in each new sleeping room. Where dwelling unit additions have basements, an emergency escape and rescue opening shall be provided in the new basement.

    Exceptions:

    1. An emergency escape and rescue opening is not required in a new basement that contains a sleeping room with an emergency escape and rescue opening.
    2. An emergency escape and rescue opening is not required in a new basement where there is an emergency escape and rescue opening in an existing basement that is accessed from the new basement.
    3. An operable window complying with Section R319.7.1 shall be acceptable as an emergency escape and rescue opening.
  • 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

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    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.

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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 § 504.3 High relevance — show source text

    [BE] 504.3 Construction. The fire escape shall be designed to support a live load of 100 pounds per square foot (4788 Pa) and shall be constructed of steel or other approved noncombustible materials. Fire escapes constructed of wood not less than nominal 2 inches (51 mm) thick are permitted on buildings of Type V construction. Walkways and railings located over or supported by combustible roofs in buildings of Type III and IV construction are permitted to be of wood not less than nominal 2 inches (51 mm) thick.

    [BE] 504.4 Dimensions. Stairways shall be not less than 22 inches (559 mm) wide with risers not more than, and treads not less than, 8 inches (203 mm) and landings at the foot of stairways not less than 40 inches (1016 mm) wide by 36 inches (914 mm) long, located not more than 8 inches (203 mm) below the door.

    [BE] 504.5 Opening protectives. Doors and windows within 10 feet (3048 mm) of fire escape stairways shall be protected with [3] / 4 hour opening protectives.

    Exception: Opening protection shall not be required in buildings equipped throughout with an approved automatic sprinkler system.

    SECTION 505—WINDOWS AND EMERGENCY ESCAPE OPENINGS

    505.1 Replacement windows. The installation or replacement of windows shall be as required for new installations.

    505.2 Window fall prevention on replacement windows. In Group R-1, R-2 or R-3 buildings containing dwelling or sleeping units, and one- and two-family dwellings and townhouses regulated by the California Residential Code, window opening control devices or other window fall prevention devices complying with ASTM F2090 shall be installed where an existing window is replaced and where all of the following apply to the replacement window:

    1. 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.

  • CHBC § 10-61 High relevance — show source text
    1. Group R-3 and R-4 occupancies.

    Basements and sleeping rooms below the fourth story above grade plane shall have not fewer than one emergency escape and rescue opening in accordance with this section. Where basements contain one or more sleeping rooms, an emergency escape and rescue opening shall be required in each sleeping room, but shall not be required in adjoining areas of the basement. Such open

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    MEANS OF EGRESS

    ings shall open directly into a public way or to a yard or court that opens to a public way, or to an egress balcony that leads to a public way.

    Exceptions: 1. In Groups R-1 and R-2 occupancies constructed of Type I, Type IIA, Type IIIA or Type IV construction equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1. 2. Group R-2.1 occupancies meeting the requirements for delayed egress in accordance with Section 1010.2.13 may have oper- able windows that are breakable in sleeping rooms permanently restricted to a maximum of 4-inch open position. 3. Basements with a ceiling height of less than 80 inches (2032 mm) shall not be required to have emergency escape and rescue openings. 4. 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 leads to a public

    way. 5. 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. 6. Storm shelters are not required to comply with this section where the shelter is constructed in accordance with ICC 500. 7. Within individual dwelling and sleeping units in Groups R-2 and R-3, where the building is equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1, 903.3.1.2 or 903.3.1.3, sleeping rooms in basements shall not be required to have emergency escape and rescue openings provided that the basement has one of the following: 7.1. One means of egress and one emergency escape and rescue opening. 7.2. Two means of egress. 8. In Group R-2.2 occupancies a certified fire escape is acceptable as a secondary means of egress of existing buildings for this section of the code.

    [BE] 1031.2.1 Operational constraints and opening control devices. Emergency escape and rescue openings and any exit doors shall be maintained free of any obstructions other than those allowed by this section and shall be operational from inside the room without the use of keys or tools. Window-opening control devices complying with ASTM F2090 shall be permitted for use on windows serving as a required emergency escape and rescue opening. 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.

  • 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.

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    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 § 1011.5.6. High relevance — show source text
    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.

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    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:

    1. The minimum net clear opening size complies with the code that was in effect at the time of construction.
    2. Such devices shall be releasable or removable from the inside without the use of a key, tool or force greater than that which is required for normal operation of the escape and rescue opening.
    3. Where such devices are installed, they shall not reduce the net clear opening of the emergency escape and rescue openings .
    4. Smoke alarms shall be installed in accordance with Section 907.2.11 of the California Building Code .

    SECTION 506—CHANGE OF OCCUPANCY

    506.1 Compliance. A change of occupancy shall not be made in any building unless that building is made to comply with the requirements of the California Building Code for the use or occupancy. Changes of occupancy in a building or portion thereof shall be such that the existing building is not less complying with the provisions of this code than the existing building or structure was prior to the change. Subject to the approval of the code official, changes of occupancy shall be permitted without complying with all of the requirements of this code for the new occupancy, provided that the new occupancy is less hazardous, based on life and fire risk, than the existing occupancy.

    Exception: The building need not be made to comply with Chapter 16 of the California Building Code unless required by Section 506.5.

    506.1.1 Change in the character of use. A change of occupancy with no change of occupancy classification shall not be made to any structure that will subject the structure to any special provisions of the applicable California Codes, without approval of the code official. Compliance shall be only as necessary to meet the specific provisions and is not intended to require the entire building be brought into compliance.

    506.1.2 Change in function. [OSHPD 1R, 2, 4 and 5] A change in function shall require compliance with all the functional require- ments for new construction in the California Building Code, including requirements in Sections 1224, 1225, 1226, 1227 and 1228.

  • 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 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.

    R319.2.3 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.

    R319.2.4 Emergency escape and rescue openings under decks, porches and cantilevers. Emergency escape and rescue openings installed under decks, porches and cantilevers shall be fully openable and provide a path not less than 36 inches (914 mm) in height and 36 inches (914 mm) in width to a yard or court.

    R319.3 Emergency escape and rescue doors. Where a door is provided as the required emergency escape and rescue opening, it shall be a side-hinged door or a sliding door.

    R319.4 Area wells. An emergency escape and rescue opening where the bottom of the clear opening is below the adjacent grade shall be provided with an area well in accordance with Sections R319.4.1 through R319.4.4.

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    BUILDING PLANNING

    R319.4.1 Minimum size. The horizontal area of the area well shall be not less than 9 square feet (0.9 m [2] ), with a horizontal projection and width of not less than 36 inches (914 mm). The size of the area well shall allow the emergency escape and rescue opening to be fully opened.

    Exception: The ladder or steps required by Section R319.4.2 shall be permitted to encroach not more than 6 inches (152 mm) into the required dimensions of the area well.

    R319.4.2 Ladder and steps. Area wells with a vertical depth greater 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 where the window or door is in the open position. Ladders or steps required by this section shall not be required to comply with Section R318.7.

  • CHBC § 701.1 High relevance — show source text

    701.1 Scope. Level 1 alterations as described in Section 602 shall comply with the requirements of this chapter. Alterations to historic buildings and structures shall comply with Part 8, Title 24, C.C.R.

    701.2 Conformance. An existing building or portion thereof shall not be altered such that the building becomes less safe than its existing condition.

    Exception: Where the current level of safety or sanitation is proposed to be reduced, the portion altered shall conform to the requirements of the California Building Code .

    [BS] 701.3 Flood hazard areas. In flood hazard areas, alterations that constitute substantial improvement shall require that the building comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.

    SECTION 702—BUILDING ELEMENTS AND MATERIALS

    702.1 Interior finishes. Newly installed interior wall and ceiling finishes shall comply with Chapter 8 of the California Building Code .

    702.2 Interior floor finish. New interior floor finish, including new carpeting used as an interior floor finish material, shall comply with Section 804 of the California Building Code .

    702.3 Interior trim. Newly installed interior trim materials shall comply with Section 806 of the California Building Code .

    702.4 Window fall prevention. In Group R-2 or R-3 buildings containing dwelling units and one- and two-family dwellings and townhouses regulated by the California Residential Code, window opening control devices or other window fall prevention devices complying with ASTM F2090 shall be installed where an existing window is replaced and where all of the following apply to the replacement window:

    1. 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 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.

    702.5 Replacement window for 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 R310.2 of the California Residential Code, provided that the replacement window meets the following conditions: 1.

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

    12-3-1.2 These requirements only cover the ability of the releasing system to be manually activated from the interior of a dwelling unit by an occupant to affect an escape through the protected opening.

    12-3-1.3 These requirements cover releasing systems intended for use on the interior side of doors or windows in all climatic locations.

    12-3-1.4 These requirements do not evaluate the ability of the releasing system or obstructions to resist an external forced entry attack.

    12-3-1.5 These requirements do not evaluate the ability of the releasing system or obstructions to be opened or removed from the exterior of the residential dwelling unit by emergency response personnel during rescue operations.

    12-3-1.6 Products covered by these requirements are intended for installation in dwelling units to protect door and window openings that are designated by the California Building Standards Code to be used as the secondary means of escape from the living area.

    12-3-1.7 Products covered by these requirements are not intended to be used to protect doors in means of egress path for nonresidential occupancies, the common egress path of multifamily residential dwelling units or the primary means of egress path in a single-family dwelling unit.

    12-3-1.8 These requirements do not cover window guards or fall prevention devices that are intended to prevent falls from upper story windows.

    12-3-1.9 These requirements do not apply to storm doors and windows or light duty screens used for insect control.

    12-3-1.10 A product that contains features, characteristics, components or materials new or different from those covered by these requirements, and that involve a risk of fire, electric shock or injury to persons shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain an acceptable level of safety.

    SECTION 12-3-2—GENERAL

    12-3-2.1 Components.

    12-3-2.1.1 Except as indicated in Section 12-3-2.1.2, a component of a product covered shall comply with the requirements for that component.

    12-3-2.1.2 A component need not comply with a specific requirement that: (a) Involves a feature or characteristic not needed in the application of the component in the product covered by these requirements, or (b) Is superseded by these requirements.

    12-3-2.1.3 A component shall be used in accordance with its recognized rating established for the intended conditions of use.

    12-3-2.1.4 Specific components are recognized as being incomplete in construction features or restricted in performance capabilities. Such components are intended for use only under limited conditions, such as certain temperatures not exceeding specific limits, and shall be used only under those specific conditions for which they have been recognized.

    12-3-2.2 Units of measurement.

    12-3-2.2.1 When a value for measurement is followed by a value in other units in parentheses, the first stated value is the requirement.

    12-3-2.3 Installation instructions.

    12-3-2.3.1 A copy of the operating and installation instructions or equivalent information is to be furnished with the samples submitted for investigation for use as a guide in the examination and test of the mechanism. For this purpose, a printed edition is not required.

    12-3-2.4 Definitions.

  • CHBC § 8-408 High relevance — show source text

    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

    CHAPTER 8-6 ACCESSIBILITY . . . . . . . . . . . . . . . . . . . . . . . . 11

    Section

    8-601 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 11

    8-602 Basic Provisions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

    8-603 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

    8-604 Equivalent Facilitation. . . . . . . . . . . . . . . . . . . . . . . . . . 12

    CHAPTER 8-7 STRUCTURAL REGULATIONS. . . . . . . . . . . . . 13

    Section

    8-701 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 13 8-702 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

    8-703 Structural Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8-704 Nonhistorical Additions and

    Nonhistorical Alterations . . . . . . . . . . . . . . . . . . . . . . . 13

  • CHBC § 8-302.3 High relevance — show source text

    8-302.3 Occupancy separations. Required occupancy separations of more than one hour may be reduced to one-hour fire-resistive construction with all openings protected by not less than three-fourths-hour fire-resistive assemblies of the self-closing or automatic-closing type when the building is provided with an automatic sprinkler system throughout the entire building in accordance with Section 8-410.2. Doors equipped with automatic-closing devices shall be of a type which will function upon activation of a device which responds to products of combustion other than heat.

    Required occupancy separations of one hour may be omitted when the building is provided with an automatic sprinkler system throughout.

    8-302.4 Maximum floor area. Regardless of the use or character of occupancy, the area of a one-story qualified historical building or property may have, but shall not exceed, a floor area of 15,000 square feet (1393.5 m [2] ) unless such an increase is otherwise permitted in regular code. Multistory qualified historical buildings (including basements and cellars) shall be in accordance with regular code requirements.

    Exception: Historical buildings may be unlimited in floor area without fire-resistive area separation walls:

    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

Frequently asked questions

Can I use a door instead of a window to satisfy the requirement?

Yes. § 8-503 allows an openable window or door approved for emergency escape so a side‑hinged or sliding door that opens directly to a yard/public way and provides the required clear opening will satisfy the CHBC requirement, provided it meets the operability and clear-area requirements .

Do sill-height (maximum) limits in the regular code apply under the CHBC?

The CHBC text of § 8-503 as retrieved does not include a maximum sill-height (bottom-of-clear-opening) limit. If you are relying on the CHBC, do not assume regular-code sill-height limits automatically apply; check with the enforcing agency or whether regular-code application is required for your work .

Can security bars be installed over required escape openings?

Security bars may be possible, but the opening must still be operable from the inside to provide a full, clear opening without special tools. Any bars must not reduce the net clear opening and must be releasable from the inside; otherwise the opening will not meet § 8-503 .

Is the CHBC minimum area (3.3 ft²) smaller than the regular code?

Yes. CHBC § 8-503 sets a 3.3 ft² minimum clear area. The regular CBC/CRC emergency opening minimums in other code sections are larger in many cases (see regular code excerpts in the file set) — confirm which code applies to your project .

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California Historical Building Code