CBC · California Building Code

When is a fire wall required and how must it be constructed/continued?

A fire wall (CBC § 706) is a specially constructed noncombustible wall that creates a complete separation between buildings or areas and must remain standing even if adjacent structures collapse; the CBC prescribes required fire‑resistance ratings by occupancy (§ 706.4), continuity and extensions beyond exterior walls (§ 706.5), opening size and protection limits (§ 706.8), and that joints/penetrations comply with the referenced joint and penetration sections (§ 706.10 and § 706.9) — follow those specific code sections and the Table 706.4 mapping when designing or reviewing a fire wall.

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Last reviewed: July 5, 2026

What the code requires — 2-4 sentences

A fire wall is a continuous, noncombustible wall assembly that creates a complete separation between buildings or building areas and is sized and detailed to remain standing even if the structure on either side collapses. The California Building Code requires fire walls to be built where a complete separation is needed (including party walls) and to meet structural stability, fire‑resistance rating, continuity and opening limitations set out in Section 706 and its subsections (see § 706, § 706.2, § 706.4, § 706.5, § 706.8, § 706.10) .

Requirements in detail

Purpose and where required

  • Fire walls provide a complete separation to either create distinct buildings (party walls on lot lines) or to separate occupancies/areas that the code requires to be separated (§ 706.1) .
  • Party walls located on lot lines used jointly between adjacent buildings must be constructed as fire walls without openings (§ 706.1.1) .

Structural stability

  • A fire wall must be designed and constructed so the structure on either side may collapse without causing collapse of the wall under fire conditions; this is a fundamental difference from ordinary fire barriers (§ 706.2) .
  • Note: a seismic-related exception applies where NFPA 221 double fire walls are used in Seismic Design Categories D–F (see § 706.2 for specifics) .

Fire‑resistance rating (key decision dimension)

Use Table 706.4 to determine required fire-resistance rating by occupancy type; Type II or V construction may allow reduced rating in some groups (§ 706.4) .

Decision dimension Typical value Code Reference
Occupancy groups A, B, E, H‑4, I, R‑1, R‑2, R‑2.1, R‑2.2, U, L 3 hours (2 hours allowed in Type II or V) § 706.4
Groups F‑1, H‑3b, H‑5, M, S‑1 3 hours § 706.4
Groups H‑1, H‑2 4 hours (see special H sections) § 706.4
Groups F‑2, S‑2, R‑3, R‑4 2 hours § 706.4

(Always consult Table 706.4 itself for the full occupancy-to-rating mapping and the footnote exceptions; the code text determines the exact rating for your occupancy.) § 706.4 .

Horizontal and vertical continuity / termination

  • Fire walls must be continuous from exterior wall to exterior wall and must extend at least 18 inches beyond the exterior surface of exterior walls (§ 706.5) .
  • Exception: a fire wall may terminate at the interior surface of combustible exterior sheathing or siding if the adjacent exterior wall has at least a 1-hour fire‑resistance rating for 4 feet on both sides of the fire wall and openings are protected to 3/4 hour (§ 706.5, Exceptions) .
  • Where a fire wall serves as an interior wall and a sloped roof rises toward it, the wall extension height is governed by § 706.6.2 (roof continuations) — see code for the 30‑inch minimum and the measurement method .

Openings, penetrations, joints

  • Openings through a fire wall are strictly limited: each opening must be protected in accordance with Section 716 and not exceed 156 sq ft individually; the aggregate width of openings at any floor level must not exceed 25% of the wall length (§ 706.8) .
  • Party walls constructed under § 706.1.1 do not permit openings (§ 706.8, Exception 1) .
  • Penetrations must comply with Section 714 and are controlled to preserve the wall’s required rating (§ 706.9 referenced in the code) .
  • Joints in or between fire walls must comply with Section 715; joint systems and voids at intersections must be detailed to maintain the wall’s fire performance (§ 706.10) .

Materials and construction practice

  • Fire walls must be constructed of approved noncombustible materials; an exception exists for buildings of Type V construction (§ 706.3) .
  • Fire walls meeting NFPA 221 design and construction are deemed to comply with CBC Section 706, subject to code limitations; the required fire‑resistance rating is still determined by § 706.4 (§ 706.1.2) .

Exceptions & special cases

  • Party walls: must be opening‑free and create separate buildings, except narrow exceptions for malls/anchors found elsewhere (§ 706.1.1) .
  • NFPA 221: designs per NFPA 221 are allowed as an alternate means to comply (§ 706.1.2) .
  • Reduced openings: if both buildings separated by a fire wall are fully sprinklered, the 156 sq ft individual opening limit may be relaxed (§ 706.8, Exception 2) .
  • Seismic exception: in SD C/D/E/F, double fire walls under NFPA 221 permit limited continuity of light framing members through the wall (see § 706.2 exception) .
  • Roof terminations: under certain conditions a fire wall that is part of an exterior wall separating buildings of different roof levels may terminate at the underside of the lower roof sheathing (see the exception in § 706.5 and the three required conditions) .

If you need a specific situational exception interpreted (for example, where a fire wall intersects a curtain wall, or how a local fire department requirement interacts), that often requires plan review and approval by the building official; the code frequently defers to those reviews (§ 706.1 exceptions) .

Common mistakes

  • Treating a fire wall like a fire barrier or partition — fire walls must remain structurally stable if adjacent construction collapses; this is a higher requirement than a typical fire barrier (§ 706.2) .
  • Forgetting the 18‑inch horizontal extension beyond exterior walls or improperly terminating the wall without meeting the specific exceptions in § 706.5 .
  • Allowing too-large or too many unprotected openings: individual openings >156 sq ft or aggregate widths >25% at a floor level violate § 706.8 unless the sprinkler exception applies .
  • Using combustible materials in the wall assembly when noncombustible construction is required (§ 706.3) .
  • Neglecting joints and penetrations: joints must follow Section 715 and penetrations Section 714 to preserve the rated assembly (§ 706.10, § 706.9) .

Worked example — concrete scenario

Scenario: Two Type IIB buildings (Group B and Group R‑2 portions) are separated by a common fire wall 60 feet long at a given floor level. The owner proposes three openings in the wall at that level: one storefront opening 120 sq ft and two 40 sq ft openings.

Step 1 — Required rating:

  • For Groups A/B/E/... Table 706.4 requires a 3‑hour fire wall for many occupancies; for Group R‑2 the table also lists 3 hours for certain group combinations — confirm the exact group pairing in Table 706.4. Use § 706.4 to select the required rating and check Type IIB allowances (Type II or V may permit 2 hours in some groups) (§ 706.4) .

Step 2 — Openings sizing:

  • Individual opening limit: 156 sq ft max — the 120‑sq‑ft storefront is OK individually; the 40‑sq‑ft openings are OK individually (§ 706.8) .
  • Aggregate width (or area) limit at the floor level: openings’ aggregate width must not exceed 25% of the wall’s length. If the 60‑ft wall is measured, 25% = 15 ft allowed aggregate width. Calculate actual aggregate width of the three openings; if their combined widths exceed 15 ft, the design must be changed or the sprinkler exception invoked (§ 706.8) .

Step 3 — Protection:

  • Each opening will need to be protected to the fire protection rating required by Section 716 (fire door/glazing assemblies), consistent with the wall’s required rating (§ 706.8 and § 716) .

Step 4 — Continuity:

  • Ensure the wall extends to and beyond exterior walls by 18 inches unless terminating under an allowable exception (if it terminates at interior surface of combustible siding, adjacent exterior walls must have 1‑hour rating for 4 ft on both sides and openings protected to 3/4‑hour) (§ 706.5) .

If the owner wants larger or more openings than permitted, one option is to provide automatic sprinklers throughout both sides (see § 706.8 exception) and then re-evaluate allowable opening sizing with the authority having jurisdiction (§ 706.8) .

Related provisions

  • § 706.1 — General and party wall rules for fire walls
  • § 706.2 — Structural stability requirement for fire walls
  • § 706.3 — Materials (noncombustible) for fire walls
  • § 706.4 — Fire‑resistance rating requirements (Table 706.4)
  • § 706.5 — Horizontal continuity and extensions beyond exterior walls (and exceptions)
  • § 706.8 — Openings limits and protection requirements (§ 716 referenced)
  • § 706.9 — Penetrations (referenced to § 714)
  • § 706.10 — Joints (must comply with § 715)
  • § 706.11 — Ducts and air transfer openings rules and exception for non‑lot‑line walls (§ 717 referenced)
  • § 715 — Joint systems and voids (applies where § 706.10 points to joints)
  • § 716 — Opening protectives requirements called out by § 706.8

Code references

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

  • CBC § 1026.2 High relevance — show source text

    1026.2 Separation. The separation between buildings or refuge areas connected by a horizontal exit shall be provided by a fire wall complying with Section 706; or by a fire barrier complying with Section 707 or a horizontal assembly complying with Section 711, or both. The minimum fire-resistance rating of the separation shall be 2 hours. Opening protectives in horizontal exits shall also comply with Section 716. Duct and air transfer openings in a fire wall or fire barrier that serves as a horizontal exit shall also comply with

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    Section 717. The horizontal exit separation shall extend vertically through all levels of the building unless floor assemblies have a fire-resistance rating of not less than 2 hours and do not have unprotected openings.

    Exception: A fire-resistance rating is not required at horizontal exits between a building area and an above-grade pedestrian walkway constructed in accordance with Section 3104, provided that the distance between connected buildings is more than 20 feet (6096 mm).

    Horizontal exits constructed as fire barriers shall be continuous from exterior wall to exterior wall so as to divide completely the floor served by the horizontal exit.

    1026.3 Opening protectives. Fire doors in horizontal exits shall be self-closing or automatic-closing when activated by a smoke detector in accordance with Section 716.2.6.6. Doors, where located in a cross-corridor condition, shall be automatic-closing by activation of a smoke detector installed in accordance with Section 716.2.6.6.

    1026.4 Refuge area. The refuge area of a horizontal exit shall be a space occupied by the same tenant or a public area and each such refuge area shall be adequate to accommodate the original occupant load of the refuge area plus the occupant load anticipated from the adjoining compartment. The anticipated occupant load from the adjoining compartment shall be based on the capacity of the horizontal exit doors entering the refuge area or the total occupant load of the adjoining compartment, whichever is less.

    1026.4.1 Capacity. The capacity of the refuge area shall be computed based on a net floor area allowance of 3 square feet (0.2787 m [2] ) for each occupant to be accommodated therein. Where the horizontal exit also forms a smoke compartment, the capacity of the refuge area for Group I-2, I-3 and R-2.1 occupancies and ambulatory care facilities shall comply with Sections 407.5.3, 408.6.2, 420.6.2 and 422.3.2 as applicable.

    1026.4.2 Number of exits. The refuge area into which a horizontal exit leads shall be provided with exits adequate to meet the occupant requirements of this chapter, but not including the added occupant load imposed by persons entering the refuge area through horizontal exits from other areas. In other than I-3 occupancies, not less than one refuge area exit shall lead directly to the exterior or to an interior exit stairway or ramp.

    Exception: The adjoining compartment shall not be required to have a stairway or door leading directly outside, provided that the refuge area into which a horizontal exit leads has stairways or doors leading directly outside and are so arranged that egress shall not require the occupants to return through the compartment from which egress originates.

    1026.5 Standpipes. Standpipes and standpipe hose connections shall be provided where required by Sections 905.3 and 905.4.

  • CBC § 705.12.1 High relevance — show source text

    705.12.1 Parapet construction. Required parapets shall have the same fire-resistance rating as that required for the supporting wall, and on any side adjacent to a roof surface, shall have noncombustible faces for the uppermost 18 inches (457 mm), including counterflashing and coping materials. The height of the parapet shall be not less than 30 inches (762 mm) above the point where the roof surface and the wall intersect. Where the roof slopes toward a parapet at a slope greater than 2 units vertical in 12 units horizontal (16.7-percent slope), the parapet shall extend to the same height as any portion of the roof within a fire separation distance where protection of wall openings is required, but the height shall be not less than 30 inches (762 mm).

    705.13 Exterior graphics on exterior walls of high-rise buildings. Where installed on the exterior walls of high-rise buildings, exterior graphics, both permanent and temporary, greater than 100 square feet in area or greater than 10 feet in either dimension shall comply with the following conditions subject to the review and approval of the fire code official and building official: 1. The materials used for graphics installed at a height greater than 40 feet above the grade plane shall be noncombustible mate- rials or shall have a flame spread index not greater than 25 when tested in accordance with ASTM E84 or UL 723.

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    2. The method of attachment and mounting of the graphics to the exterior wall shall be such that the graphics are securely attached.

    3. The graphics shall not interfere with the active or passive ventilation required for the building and the required smoke control systems in the building. 4. The graphics shall not impair the functions of any fire or life safety systems in the building.

    SECTION 706—FIRE WALLS

    706.1 General. Fire walls shall be constructed in accordance with Sections 706.2 through 706.11. The extent and location of such fire walls shall provide a complete separation. Where a fire wall separates occupancies that are required to be separated by a fire barrier wall, the most restrictive requirements of each separation shall apply.

    706.1.1 Party walls. Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

    Exceptions:

    1. Openings in a party wall separating an anchor building and a mall shall be in accordance with Section 402.4.2.2.1.
    2. Party walls and fire walls are not required on lot lines dividing a building for ownership purposes where the aggregate height and area of the portions of the building located on both sides of the lot line do not exceed the maximum height and area requirements of this code. For the building official’s review and approval, the official shall be provided with copies of dedicated access easements and contractual agreements that permit the owners of portions of the building located on either side of the lot line access to the other side for purposes of maintaining fire and life safety systems necessary for the operation of the building.
  • CBC § 706.1 High relevance — show source text

    FIRE AND SMOKE PROTECTION FEATURES

    2. The method of attachment and mounting of the graphics to the exterior wall shall be such that the graphics are securely attached.

    3. The graphics shall not interfere with the active or passive ventilation required for the building and the required smoke control systems in the building. 4. The graphics shall not impair the functions of any fire or life safety systems in the building.

    SECTION 706—FIRE WALLS

    706.1 General. Fire walls shall be constructed in accordance with Sections 706.2 through 706.11. The extent and location of such fire walls shall provide a complete separation. Where a fire wall separates occupancies that are required to be separated by a fire barrier wall, the most restrictive requirements of each separation shall apply.

    706.1.1 Party walls. Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

    Exceptions:

    1. Openings in a party wall separating an anchor building and a mall shall be in accordance with Section 402.4.2.2.1.
    2. Party walls and fire walls are not required on lot lines dividing a building for ownership purposes where the aggregate height and area of the portions of the building located on both sides of the lot line do not exceed the maximum height and area requirements of this code. For the building official’s review and approval, the official shall be provided with copies of dedicated access easements and contractual agreements that permit the owners of portions of the building located on either side of the lot line access to the other side for purposes of maintaining fire and life safety systems necessary for the operation of the building.

    706.1.2 Deemed to comply. Fire walls designed and constructed in accordance with NFPA 221 shall be deemed to comply with this section, subject to the limitations of Section 102.4. The required fire-resistance rating shall be determined by Section 706.4.

    706.2 Structural stability. Fire walls shall be designed and constructed to allow collapse of the structure on either side without collapse of the wall under fire conditions.

    Exception: In Seismic Design Categories D through F, where double fire walls are used in accordance with NFPA 221, floor and roof sheathing not exceeding [3] / 4 inch (19.05 mm) thickness shall be permitted to be continuous through the wall assemblies of light frame construction.

    706.3 Materials. Fire walls shall be of any approved noncombustible materials.

    Exception: Buildings of Type V construction.

    706.4 Fire-resistance rating. Fire walls shall have a fire-resistance rating of not less than that required by Table 706.4.

  • CBC § 402.4.2.2.1. High relevance — show source text

    Exceptions:

    1. Openings in a party wall separating an anchor building and a mall shall be in accordance with Section 402.4.2.2.1.
    2. Party walls and fire walls are not required on lot lines dividing a building for ownership purposes where the aggregate height and area of the portions of the building located on both sides of the lot line do not exceed the maximum height and area requirements of this code. For the building official’s review and approval, the official shall be provided with copies of dedicated access easements and contractual agreements that permit the owners of portions of the building located on either side of the lot line access to the other side for purposes of maintaining fire and life safety systems necessary for the operation of the building.

    706.1.2 Deemed to comply. Fire walls designed and constructed in accordance with NFPA 221 shall be deemed to comply with this section, subject to the limitations of Section 102.4. The required fire-resistance rating shall be determined by Section 706.4.

    706.2 Structural stability. Fire walls shall be designed and constructed to allow collapse of the structure on either side without collapse of the wall under fire conditions.

    Exception: In Seismic Design Categories D through F, where double fire walls are used in accordance with NFPA 221, floor and roof sheathing not exceeding [3] / 4 inch (19.05 mm) thickness shall be permitted to be continuous through the wall assemblies of light frame construction.

    706.3 Materials. Fire walls shall be of any approved noncombustible materials.

    Exception: Buildings of Type V construction.

    706.4 Fire-resistance rating. Fire walls shall have a fire-resistance rating of not less than that required by Table 706.4.

    TABLE 706.4—FIRE WALL FIRE-RESISTANCE RATINGS Col2
    GROUP FIRE-RESISTANCE RATING (hours)
    A, B, E, H-4, I, R-1, R-2,_R-2.1, R-2.2,_U,L 3 a
    F-1, H-3b, H-5, M, S-1 3
    H-1, H-2 4 b
    F-2, S-2, R-3, R-4 2
    a. In Type II or V construction, walls shall be permitted to have a 2-hour fire-resistance rating.
    b. For Group H-1, H-2 or H-3 buildings, also see Sections 415.7 and 415.8.    		 a. In Type II or V construction, walls shall be permitted to have a 2-hour fire-resistance rating.
    b. For Group H-1, H-2 or H-3 buildings, also see Sections 415.7 and 415.8.

    706.5 Horizontal continuity. Fire walls shall be continuous from exterior wall to exterior wall and shall extend not less than 18 inches (457 mm) beyond the exterior surface of exterior walls.

    Exceptions:

    1. Fire walls shall be permitted to terminate at the interior surface of combustible exterior sheathing or siding provided that the exterior wall has a fire-resistance rating of not less than 1 hour for a horizontal distance of not less than 4 feet (1220 mm) on both sides of the fire wall. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.
  • CBC § 706.6.2 High relevance — show source text

    FIRE AND SMOKE PROTECTION FEATURES

    construction from both sides with openings protected by fire assemblies having a fire protection rating of not less than [3] / 4 hour. Portions of the exterior walls greater than 15 feet (4572 mm) above the lower roof shall be of nonfire-resistance-rated construction unless otherwise rated construction is required by other provisions of this code.

    Exception: A fire wall serving as part of an exterior wall that separates buildings having different roof levels shall be permitted to terminate at the underside of the roof sheathing, deck or slab of the lower roof, provided that Items 1, 2 and 3 are met. The exterior wall above the fire wall is not required to be of fire-resistance-rated construction unless required by other provisions of this code.

    1. The lower roof assembly within 10 feet (3048 mm) of the fire wall has not less than a 1-hour fire-resistance rating.

    2. The entire length and span of supporting elements for the rated roof assembly shall have a fire -resistance rating of not less than 1 hour.

    3. Openings in the lower roof shall not be located within 10 feet (3048 mm) of the fire wall.

    706.6.2 Buildings with sloped roofs. Where a fire wall serves as an interior wall for a building, and the roof on one side or both sides of the fire wall slopes toward the fire wall at a slope greater than 2 units vertical in 12 units horizontal (2:12), the fire wall shall extend to a height equal to the height of the roof located 4 feet (1219 mm) from the fire wall plus 30 inches (762 mm). The extension of the fire wall shall be not less than 30 inches (762 mm).

    706.7 Combustible framing in fire walls. Adjacent combustible members entering into a concrete or masonry fire wall from opposite sides shall not have less than a 4-inch (102 mm) distance between embedded ends. Where combustible members frame into hollow walls or walls of hollow units, hollow spaces shall be solidly filled for the full thickness of the wall and for a distance not less than 4 inches (102 mm) above, below and between the structural members, with noncombustible materials approved for fireblocking.

    706.8 Openings. Each opening through a fire wall shall be protected in accordance with Section 716 and shall not exceed 156 square feet (15 m [2] ). The aggregate width of openings at any floor level shall not exceed 25 percent of the length of the wall.

    Exceptions:

    1. Openings are not permitted in party walls constructed in accordance with Section 706.1.1.
    2. Openings shall not be limited to 156 square feet (15 m [2] ) where both buildings are equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1.

    706.9 Penetrations. Penetrations of fire walls shall comply with Section 714.

    706.10 Joints. Joints made in or between fire walls shall comply with Section 715.

    706.11 Ducts and air transfer openings. Ducts and air transfer openings shall not penetrate fire walls.

    Exception: Penetrations by ducts and air transfer openings of fire walls that are not on a lot line shall be allowed provided that the penetrations comply with Section 717. The size and aggregate width of all openings shall not exceed the limitations of Section 706.8.

    SECTION 707—FIRE BARRIERS

  • CBC § 1025.5 High relevance — show source text

    1. UL 1994.

    2. ASTM E2072, except that the charging source shall be 1 footcandle (11 lux) of fluorescent illumination for 60 minutes, and the minimum luminance shall be 30 milicandelas per square meter at 10 minutes and 5 milicandelas per square meter after 90 minutes.

    1025.5 Illumination. Where photoluminescent exit path markings are installed, they shall be provided with not less than 1 footcandle (11 lux) of illumination for not less than 60 minutes prior to periods when the building is occupied and continuously during

    occupancy.

    SECTION 1026—HORIZONTAL EXITS

    1026.1 General. Horizontal exits serving as an exit in a means of egress system shall comply with the requirements of this section. A horizontal exit shall not serve as the only exit from a portion of a building, and where two or more exits are required, not more than one-half of the total number of exits or total exit minimum width or required capacity shall be horizontal exits.

    Exceptions:

    1. Horizontal exits are permitted to comprise two-thirds of the required exits from any building or floor area for occupancies in Group I-2.
    2. Horizontal exits are permitted to comprise 100 percent of the exits required for occupancies in Group I-3. Not less than 6 square feet (0.6 m [2] ) of accessible space per occupant shall be provided on each side of the horizontal exit for the total number of people in adjoining compartments.

    1026.2 Separation. The separation between buildings or refuge areas connected by a horizontal exit shall be provided by a fire wall complying with Section 706; or by a fire barrier complying with Section 707 or a horizontal assembly complying with Section 711, or both. The minimum fire-resistance rating of the separation shall be 2 hours. Opening protectives in horizontal exits shall also comply with Section 716. Duct and air transfer openings in a fire wall or fire barrier that serves as a horizontal exit shall also comply with

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    Section 717. The horizontal exit separation shall extend vertically through all levels of the building unless floor assemblies have a fire-resistance rating of not less than 2 hours and do not have unprotected openings.

    Exception: A fire-resistance rating is not required at horizontal exits between a building area and an above-grade pedestrian walkway constructed in accordance with Section 3104, provided that the distance between connected buildings is more than 20 feet (6096 mm).

    Horizontal exits constructed as fire barriers shall be continuous from exterior wall to exterior wall so as to divide completely the floor served by the horizontal exit.

    1026.3 Opening protectives. Fire doors in horizontal exits shall be self-closing or automatic-closing when activated by a smoke detector in accordance with Section 716.2.6.6. Doors, where located in a cross-corridor condition, shall be automatic-closing by activation of a smoke detector installed in accordance with Section 716.2.6.6.

  • CBC § 708.3 High relevance — show source text

    708.3 Fire-resistance rating. Fire partitions shall have a fire-resistance rating of not less than 1 hour.

    Exceptions:

    1. Corridor walls permitted to have a [1] / 2 -hour fire-resistance rating by Table 1020.2.
    2. Dwelling unit and sleeping unit separations in buildings of Types IIB, IIIB and VB construction shall have fire-resistance ratings of not less than [1] / 2 hour in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

    3. Walls separating enclosed tenant spaces in Group B high-rise buildings of Type I and II construction equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

    708.4 Continuity. Fire partitions shall extend from the top of the foundation or floor/ceiling assembly below and be securely attached to one of the following:

    1. The underside of the floor or roof sheathing, deck or slab above.
    2. The underside of a floor/ceiling or roof/ceiling assembly having a fire-resistance rating that is not less than the fire-resistance rating of the fire partition.

    Exceptions:

    1. Fire partitions shall not be required to extend into a crawl space below where the floor above the crawl space has a minimum 1-hour fire-resistance rating.

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    1. Fire partitions serving as a corridor wall shall not be required to extend above the lower membrane of a corridor ceiling provided that the corridor ceiling membrane is equivalent to corridor wall membrane, and either of the following conditions is met:

    2.1. The room-side membrane of the corridor wall extends to the underside of the floor or roof sheathing, deck or slab of a fire-resistance-rated floor or roof above.

    2.2. The building is equipped with an automatic sprinkler system installed throughout in accordance with Section 903.3.1.1 or 903.3.1.2, including automatic sprinklers installed in the space between the top of the fire partition and underside of the floor or roof sheathing, deck or slab above. 3. Fire partitions serving as a corridor wall shall be permitted to terminate at the upper membrane of the corridor ceiling assembly where the corridor ceiling is constructed as required for the corridor wall. 4. Fire partitions separating tenant spaces in a covered or open mall building complying with Section 402.4.2.1 shall not be required to extend above the underside of a ceiling. Such ceiling shall not be required to be part of a fire-resistance-rated assembly, and the attic or space above the ceiling at tenant separation walls shall not be required to be subdivided by fire partitions.

    708.4.1 Fire partition walls enclosing elevator lobbies. Fire partition walls used to enclose elevator lobbies in accordance with Section 3006.3 shall form an enclosure that terminates at a fire barrier or fire partition having a fire-resistance rating of not less than 1 hour, or an outside wall.

    708.4.2 Supporting construction. The supporting construction for a fire partition shall have a fire-resistance rating that is equal to or greater than the required fire-resistance rating of the supported fire partition.

  • CBC § 1025.5 High relevance — show source text

    [BE] 1025.5 Illumination. Where photoluminescent exit path markings are installed, they shall be provided with not less than 1 footcandle (11 lux) of illumination for not less than 60 minutes prior to periods when the building is occupied and continuously during the building occupancy.

    SECTION 1026—HORIZONTAL EXITS

    [BE] 1026.1 General. Horizontal exits serving as an exit in a means of egress system shall comply with the requirements of this section. A horizontal exit shall not serve as the only exit from a portion of a building, and where two or more exits are required, not more than one-half of the total number of exits or total exit minimum width or required capacity shall be horizontal exits.

    Exceptions:

    1. Horizontal exits are permitted to comprise two-thirds of the required exits from any building or floor area for occupancies in Group I-2.
    2. Horizontal exits are permitted to comprise 100 percent of the exits required for occupancies in Group I-3. Not less than 6 square feet (0.6 m [2] ) of accessible space per occupant shall be provided on each side of the horizontal exit for the total number of people in adjoining compartments.

    [BE] 1026.2 Separation. The separation between buildings or refuge areas connected by a horizontal exit shall be provided by a fire wall complying with Section 706 of the California Building Code ; or by a fire barrier complying with Section 707 of the California Build- ing Code or a horizontal assembly complying with Section 711 of the California Building Code, or both. The minimum fire-resistance rating of the separation shall be 2 hours. Opening protectives in horizontal exits shall also comply with Section 716 of the California Building Code . Duct and air transfer openings in a fire wall or fire barrier that serves as a horizontal exit shall also comply with Section 717 of the California Building Code . The horizontal exit separation shall extend vertically through all levels of the building unless floor assemblies have a fire-resistance rating of not less than 2 hours and do not have unprotected openings.

    Exception: A fire-resistance rating is not required at horizontal exits between a building area and an above-grade pedestrian walkway constructed in accordance with Section 3104 of the California Building Code, provided that the distance between connected buildings is more than 20 feet (6096 mm).

    Horizontal exits constructed as fire barriers shall be continuous from exterior wall to exterior wall so as to divide completely the floor served by the horizontal exit.

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    [BE] 1026.3 Opening protectives. Fire doors in horizontal exits shall be self-closing or automatic-closing when activated by a smoke detector in accordance with Section 716.2.6.6 of the California Building Code . Doors, where located in a cross-corridor condition, shall be automatic-closing by activation of a smoke detector installed in accordance with Section 716.2.6.6 of the California Building Code .

  • CBC § 707.3.8 Medium relevance — show source text

    707.3.8 Control areas. Fire barriers separating control areas shall have a fire-resistance rating of not less than that required in Section 414.2.4.

    707.3.9 Separated occupancies. Where the provisions of Section 508.4 are applicable, the fire barrier separating mixed occupancies shall have a fire-resistance rating of not less than that indicated in Table 508.4 based on the occupancies being separated.

    707.3.10 Fire areas. The fire barriers, fire walls, horizontal assemblies or combinations thereof separating a single occupancy into different fire areas shall have a fire-resistance rating of not less than that indicated in Table 707.3.10. The fire barriers, fire walls, horizontal assemblies or combinations thereof separating fire areas of mixed occupancies shall have a fire-resistance rating of not less than the highest value indicated in Table 707.3.10 for the occupancies under consideration.

    7-14 2025 CALIFORNIA BUILDING CODE

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

    FIRE AND SMOKE PROTECTION FEATURES

    TABLE 707.3.10—FIRE-RESISTANCE-RATING REQUIREMENTS FOR
    FIRE BARRIERS, FIRE WALLS OR HORIZONTAL ASSEMBLIES BETWEEN FIRE AREAS    		 Col2
    OCCUPANCY GROUP FIRE-RESISTANCE RATING (hours)
    H-1, H-2 4
    F-1, H-3, S-1 3
    A, B, E, F-2, H-4, H-5, I,L, M, R, S-2 2
    U 1

    707.3.11 Horizontal separation offsets. The fire-resistance rating of a fire barrier serving as the vertical offset in a horizontal building separation shall comply with Section 510.2.

    707.4 Exterior walls. Where exterior walls serve as a part of a required fire-resistance-rated shaft, or separation or enclosure for a stairway, ramp or exit passageway, such walls shall comply with the requirements of Section 705 for exterior walls and the fire-resistance-rated enclosure or separation requirements shall not apply.

    Exceptions:

    1. Exterior walls required to be fire-resistance rated in accordance with Section 1021 for exterior egress balconies, Section 1023.7 for interior exit stairways and ramps, Section 1024.8 for exit passageways and Section 1027.6 for exterior exit stairways and ramps.
    2. Exterior walls required to be fire-resistance rated in accordance with Section 1207 of the California Fire Code for enclosure of energy storage systems.

    707.5 Continuity. Fire barriers shall extend from the top of the foundation or floor/ceiling assembly below to the underside of the floor or roof sheathing, slab or deck above and shall be securely attached thereto. Such fire barriers shall be continuous through concealed space, such as the space above a suspended ceiling. Joints and voids at intersections shall comply with Sections 707.8 and 707.9

    Exceptions:

    1. Shaft enclosures shall be permitted to terminate at a top enclosure complying with Section 713.12.
    2. Interior exit stairway and ramp enclosures required by Section 1023 and exit access stairway and ramp enclosures required by Section 1019 shall be permitted to terminate at a top enclosure complying with Section 713.12.
  • CBC § 709.3 Medium relevance — show source text

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

    FIRE AND SMOKE PROTECTION FEATURES

    709.3 Fire-resistance rating. A 1-hour fire-resistance rating is required for smoke barriers.

    Exception: Smoke barriers constructed of minimum 0.10-inch-thick (2.5 mm) steel in Group I-3 buildings.

    709.4 Continuity. Smoke barriers shall form an effective membrane continuous from the top of the foundation or floor/ceiling assembly below to the underside of the floor or roof sheathing, deck or slab above, including continuity through concealed spaces, such as those found above suspended ceilings, and interstitial structural and mechanical spaces. The supporting construction shall be protected to afford the required fire-resistance rating of the wall or floor supported in buildings of other than Type IIB, IIIB or VB construction. Smoke-barrier walls used to separate smoke compartments shall comply with Section 709.4.1. Smoke-barrier walls used to enclose areas of refuge in accordance with Section 1009.6.4 or to enclose elevator lobbies in accordance with Section 405.4.3, 3007.6.2, or 3008.6.2 shall comply with Section 709.4.2.

    Exception: Smoke-barrier walls are not required in interstitial spaces where such spaces are designed and constructed with ceilings or exterior walls that provide resistance to the passage of fire and smoke equivalent to that provided by the smoke-barrier walls.

    709.4.1 Smoke-barrier assemblies separating smoke compartments. Smoke-barrier assemblies used to separate smoke compartments shall form an effective membrane enclosure that is continuous from an outside wall or smoke barrier wall to an outside wall or another smoke barrier wall and to the horizontal assemblies.

    709.4.2 Smoke-barrier walls enclosing areas of refuge or elevator lobbies. Smoke-barrier walls used to enclose areas of refuge in accordance with Section 1009.6.4, or to enclose elevator lobbies in accordance with Section 405.4.3, 3007.6.2, or 3008.6.2, shall form an effective membrane enclosure that terminates at a fire barrier wall having a fire resistance rating not less than 1 hour, another smoke barrier wall or an outside wall. A smoke and draft control door assembly as specified in Section 716.2.2.1.1 shall not be required at each elevator hoistway door where protected by an elevator lobby, at each exit door opening into a protected lobby or at each exit doorway between an area of refuge and the exit enclosure.

    709.5 Openings. Openings in a smoke barrier shall be protected in accordance with Section 716.

    Exceptions:

    1. In Group I- 2, R-2.1 and ambulatory care facilities, where a pair of opposite-swinging doors are installed across a corridor in accordance with Section 709.5.1, the doors shall not be required to be protected in accordance with Section 716. The doors shall be close fitting within operational tolerances, and shall not have a center mullion or undercuts in excess of [3] / 4 inch (19.1 mm), louvers or grilles. The doors shall have head and jamb stops, and astragals or rabbets at meeting edges. Positive latching devices are not required. Factory-applied or field-applied protective plates are not required to be labeled. Doors installed across corridors shall comply with Section 1010.1.1.
  • CBC § 3.6.3 Medium relevance — show source text

    R302.3.6.3 Other penetrations. Penetrations through the walls, ceiling and floor-level separation required in Section R302.3.6 shall be protected as required by Section R302.11, Item 4.

    R302.4 Dwelling unit rated penetrations. Penetrations of wall or floor-ceiling assemblies required to be fire-resistance rated in accordance with Section R302.2 or R302.3 shall be protected in accordance with this section.

    R302.4.1 Through penetrations. Through penetrations of fire-resistance-rated wall or floor assemblies shall comply with Section R302.4.1.1 or R302.4.1.2.

    Exceptions:

    1. Where the penetrating items are steel, ferrous or copper pipes, tubes or conduits, the annular space shall be protected as follows: 1.1. In concrete or masonry wall or floor assemblies, concrete, grout or mortar shall be permitted where installed to the full thickness of the wall or floor assembly or the thickness required to maintain the fire-resistance rating, provided that both of the following are complied with: 1.1.1. The nominal diameter of the penetrating item is not more than 6 inches (152 mm). 1.1.2. The area of the opening through the wall does not exceed 144 square inches (92 900 mm [2] ).

    3-26 2025 CALIFORNIA RESIDENTIAL CODE

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    BUILDING PLANNING

    1.2. The material used to fill the annular space shall prevent the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E119 or UL 263 time temperature fire conditions under a positive pressure differential of not less than 0.01 inch of water (3 Pa) at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated. 2. The annular space created by the penetration of water-filled fire sprinkler piping, provided that the annular space is filled using a material complying with Item 1.2 of Exception 1.

    R302.4.1.1 Fire-resistance-rated assembly. Penetrations shall be installed as tested in the approved fire-resistance-rated assembly.

    R302.4.1.2 Penetration firestop system. Penetrations shall be protected by an approved penetration firestop system installed as tested in accordance with ASTM E814 or UL 1479, with a positive pressure differential of not less than 0.01 inch of water (3 Pa) and shall have an F rating of not less than the required fire-resistance rating of the wall or floor-ceiling assembly penetrated.

    R302.4.2 Membrane penetrations. Membrane penetrations shall comply with Section R302.4.1. Where walls are required to have a fire-resistance rating, recessed fixtures shall be installed so that the required fire-resistance rating will not be reduced.

    Exceptions:

    1. Membrane penetrations of not more than 2-hour fire-resistance-rated walls and partitions by steel electrical boxes that do not exceed 16 square inches (0.0103 m [2] ) in area provided that the aggregate area of the openings through the membrane does not exceed 100 square inches (0.0645 m [2] ) in any 100 square feet (9.29 m [2] ) of wall area. The annular space between the wall membrane and the box shall not exceed [1] / 8 inch (3.1 mm).
  • CBC § 403.6.1 Medium relevance — show source text

    Fire Service Access Elevators 403.6.1, 3007 Fire Walls 706 Aircraft hangar 412.3.6.2 Combustible framing 706.7 Continuity 706.5, 706.6 Exterior walls Table 705.5, 706.5.1 Fire-resistance rating 703, 706.4 Glazing, rated 716.3.4 Inspection 110.3.8 Joints 706.10, 715 Materials 706.3

    Opening protection 706.8, 706.11, 714.4, 716, 717.5.1 Penetration 706.9, 714.4 Special provisions Covered and open mall buildings 402.4.2.2

    Group H-5 415.11.1.6 Structural stability 706.2 Fire Windows (see Opening Protectives) Fireblocking 718.2 Chimneys 718.2.5.1, 2113.20 Fireplaces 2111.13 Wood construction 718.2.1, 718.2.7,

    1405.1.3 Wood stairways 718.2.4 Fireplaces, Factory-Built 2111.14.1 Fireplaces, Masonry 202 Clearance to combustibles 2111.12

    Drawings 2111.2 General provisions 2111 Hearth extension 2111.10, 2111.11 Steel units 2111.6.1

    Fire-Resistant Construction 701.1

    Fire-Retardant-Treated Wood 2303.2

    Awnings 3105.2 Balconies 705.2.3.1

    Canopies 3105.3 Concealed spaces 718.5 Fastening 2304.10.6 Fire wall vertical continuity 706.6 Partitions 603.1

    Platforms 410.3

    Projections 705.2.3 Roof construction Table 601, 705.12, 706.6, 1505 Shakes and shingles 1505.6 Type I and II construction 603.1 Type III construction 602.3 Type IV construction 602.4 Veneer 1404.6 Firestop 714, 1705.18.1 Fireworks 307.2, 307.3, 307.5 Flamespread 803.1.2, Table 803.13 Flammable Finishes 307.1, 416 Flammable Liquids 307.4, 307.5, 406.8.2, 412, 414, 415 Flammable Solids 307.5, 415 Flashing Roof 1503.2, 1507.2.8, 1507.3.9, 1507.5.7, 1507.7.7, 1507.8.8, 1507.9.9, 1512.5 Wall, veneer 1404.4, 1404.13.7 Flood Hazard Areas Appendix G, 1612.3 Coastal A zone 1402.10, 1603.1.7, 1612.2, 1612.4 Coastal high hazard area 1402.10, 1603.1.7, 1612.2,

Frequently asked questions

When must a fire wall be used instead of a fire barrier or fire partition?

Use a fire wall where the code requires a complete separation (for example, to create separate buildings or where Table/sections require it); fire walls are designed to remain standing if adjacent structure collapses, a capability not required of ordinary fire barriers or partitions (see § 706 and § 706.2) .

How large can an opening in a fire wall be?

Individual openings are limited to 156 square feet and aggregate width at any floor level cannot exceed 25% of the wall length unless the sprinkler exception applies; every opening must be protected per Section 716 (§ 706.8) .

Do fire walls have to be noncombustible?

Yes — fire walls are required to be of approved noncombustible materials, with an explicit code exception for certain Type V buildings (§ 706.3) .

What does “allow collapse of the structure on either side” mean for design?

It means the wall must be structurally independent so fire on one side (and potential collapse) does not cause failure of the wall — this is a fundamental structural stability requirement of fire walls (§ 706.2) .

Can I run ducts through a fire wall?

Ducts and air transfer openings shall not penetrate fire walls, except limited allowance for walls not on a lot line if they comply with Section 717 and other limits (§ 706.11) .

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