CBC · California Building Code

What flame‑spread classes are required by occupancy and location?

Homeowners: the CBC requires wall and ceiling finishes to meet specific flame‑spread classes depending on the building use and where the finish is located (stairs, corridors, rooms). The exact rule is in §803.3 and Table 803.13; sprinklered buildings often allow lower classes, and an NFPA 286 test can substitute where the code requires Class A.

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Last reviewed: July 5, 2026

What the code requires

Interior wall and ceiling finishes must meet the flame‑spread classification required for the building’s occupancy and for the specific location (stairways/exit passageways, corridors/enclosures for exit access, or rooms/enclosed spaces). The required classifications are set out in Table 803.13 and enforced through the interior‑finish rule in § 803.3 (see Table 803.13) of the CBC. Where a Class A ASTM E84/UL‑723 rating is required, an alternative demonstration using NFPA 286 that meets the acceptance criteria of § 803.1.1.1 is permitted (see § 803.1.1).

Requirements in detail

How to read the rule

  • Two inputs determine the required finish class: the occupancy group (Group A, B, I, R, etc.) and the LOCATION within the building (interior exit stairways & ramps & exit passageways; corridors and enclosures for exit access stairways and ramps; or rooms and enclosed spaces). The code differentiates requirements for sprinklered versus nonsprinklered buildings. See § 803.3 and Table 803.13 for the full matrix.
  • Finish classifications follow ASTM E84/UL‑723 Class A, B, or C (flame‑spread index ranges and smoke limits) as defined in § 803.1.2; NFPA 286 testing that meets § 803.1.1.1 acceptance criteria is treated as Class A where required.

Decision‑relevant summary table (selected rows from Table 803.13)

Below are typical, decision‑relevant rows taken from Table 803.13. For the complete table and any additional occupancies or special notations, consult Table 803.13 in § 803.13 (Table 803.13 is the table identified in the CBC as the interior finish requirements by occupancy). Code references point you to the authoritative CBC table.

Occupancy group (selected) Sprinklered — Stairways / Exit passageways Sprinklered — Corridors / Exit‑access enclosures Sprinklered — Rooms & enclosed spaces Non‑sprinklered — Stairways / Exit passageways Non‑sprinklered — Corridors / Exit‑access enclosures Non‑sprinklered — Rooms & enclosed spaces Code Reference
A‑1 & A‑2 (assembly — e.g., theaters, restaurants) B B C A A (with notation d in table) B (noted) Table 803.13 / § 803.13
A‑3, A‑4, A‑5 (other assembly types) B B C A A (d) C Table 803.13 / § 803.13
B, E, M, R‑1 (business, educational, mercantile, transient lodging) B C (table shows “Cm”) C A B (table shows “Bm”) C Table 803.13 / § 803.13
F (factory/industrial) C C C B C C Table 803.13 / § 803.13
H and L (high‑hazard, low‑hazard storage subsets) B B Cg (see table notes) Not permitted in some locations (NP) NP NP Table 803.13 / § 803.13
I‑2 (hospitals/medical) B B B,h,i (see table notes) A A B Table 803.13 / § 803.13
I‑3 (custodial care, detention) A A,j B (sprinklered rooms) A (non‑sprinklered columns marked NP) NP NP Table 803.13 / § 803.13

Notes:

  • The full Table 803.13 includes footnotes and special notations (for example, “m”, “d”, “g”, “NP”, and other footnote letters) that modify where a class applies, or indicate exceptions and special installation conditions — always read the table footnotes in the CBC. The excerpted rows above are drawn directly from Table 803.13; consult the full table for every occupancy and each footnote.
  • Class definitions (Class A/B/C and smoke‑development limits) are in § 803.1.2 (Class A = flame spread index 0–25; Class B = 26–75; Class C = 76–200; smoke limits 0–450).

Test methods and alternatives

  • Standard method is ASTM E84 (UL‑723) classification (Class A/B/C) per § 803.1.2.
  • Alternative: materials tested per NFPA 286 and meeting the acceptance criteria in § 803.1.1.1 are permitted where the table requires Class A. NFPA 286 acceptance criteria are listed in § 803.1.1.1 (no ceiling spread under 40 kW exposure; no flame to sample extremity; no flashover; peak HRR ≤ 800 kW; total smoke ≤ 1000 m2).

Exceptions & special cases

  • NFPA 286 alternative: NFPA 286 that meets § 803.1.1.1 may be used in lieu of a Class A ASTM E84 rating where Class A is required.
  • Small/thin materials: materials thinner than 0.036 in (0.9 mm) applied directly to a wall or ceiling are not required to be tested (§ 803.2 thickness exemption).
  • Some occupancies/locations are marked “NP” (not permitted) for certain finishes in Table 803.13 — if the table marks NP for an occupancy/location you may not use combustible finish there; see the table footnotes for alternatives and conditions.
  • Special materials (textiles, vinyls, laminated wood veneers, HDPE/PP, site‑fabricated systems) have their own testing/mounting requirements and may require NFPA 286 or specific specimen mounting methods; see §§ 803.5–803.12.

If you need a definitive determination for an unusual material or a marginal case (e.g., a veneer applied over wood; textile wall covering; or a finish claimed to meet NFPA 286 when the table calls for Class A), provide the product test reports and the occupancy/location and I will point to the exact table row and footnote that controls.

Common mistakes

  • Reading the occupancy row but ignoring sprinkler status — many required classes relax when the building is protected by an automatic sprinkler system (Table 803.13 entries differ for sprinklered vs non‑sprinklered). Always check the correct column.
  • Failing to apply NFPA 286 limits correctly — NFPA 286 is allowed only when the acceptance criteria of § 803.1.1.1 are met; NFPA 286 test reports must show compliance with those limits.
  • Confusing floor finish rules with wall/ceiling finish rules — interior floor finish requirements are in Chapter 804 and use different tests/criteria. Make sure you consult § 803 (walls/ceilings) vs § 804 (floors).
  • Ignoring table footnotes and special notations (m, d, g, NP, etc.) that can change applicability. Always read the footnotes attached to Table 803.13.

Worked example

Scenario: A 4‑story, sprinklered hotel (Group R‑1). What flame‑spread class is required for (a) interior exit stairways and exit passageways, (b) corridors and exit‑access enclosures, and (c) guest rooms?

How to apply the code:

  1. Identify occupancy group: R‑1 (transient lodging). 2. Building is sprinklered (column = sprinklered). 3. Read the R‑1 row in Table 803.13.

From Table 803.13 (R‑1 appears with B, E, M, etc. row): For sprinklered R‑1 the table requires:

  • Interior exit stairways & ramps and exit passageways: Class B.
  • Corridors and enclosures for exit access stairways and ramps: Class C (table shows “Cm” in that row; read the table footnote “m” for the full condition).
  • Rooms and enclosed spaces (guest rooms): Class C.

If the same hotel were not sprinklered, the table requires: stairways = Class A, corridors = Class B, rooms = Class C (see non‑sprinklered columns of the same row). Always verify any table footnotes that modify these entries.

Related provisions

  • Definitions and scope for interior finish and classifications — § 803.1 (general) and § 803.1.2 (ASTM E84 / UL‑723 Class definitions).
  • NFPA 286 alternative acceptance criteria — § 803.1.1 and § 803.1.1.1.
  • Specific material and mounting test requirements (textiles, veneers, laminates, HDPE/PP, site‑fabricated systems) — §§ 803.5–803.12.
  • Interior trim limits and acceptable classes for trim — § 806.6.
  • Interior floor finish requirements (different tests and classes) — § 804.3 and related sections.

Code references

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

  • CBC § 803.1.2 High relevance — show source text

    803.1.2 Interior wall and ceiling finish materials tested in accordance with ASTM E84 or UL 723. Interior wall and ceiling finishes shall be classified in accordance with ASTM E84 or UL 723. Such interior finish materials shall be grouped in the following classes in accordance with their flame spread and smoke-developed indices: Class A: Flame spread index 0–25; smoke-developed index 0–450. Class B: Flame spread index 26–75; smoke-developed index 0–450. Class C: Flame spread index 76–200; smoke-developed index 0–450.

    Exception: Materials tested in accordance with Section 803.1.1 and as indicated in Sections 803.1.3 through 803.15.

    803.1.3 Interior wall and ceiling finish materials with specific requirements. The materials indicated in Sections 803.4 through 803.15 shall be tested as indicated in the corresponding sections.

    803.2 Stability. Interior finish materials regulated by this chapter shall be applied or otherwise fastened in such a manner that such materials will not readily become detached where subjected to room temperatures of 200°F (93°C) for not less than 30 minutes.

    803.3 Interior finish requirements based on occupancy. Interior wall and ceiling finish shall have a flame spread index not greater than that specified in Table 803.3 for the group and location designated. Interior wall and ceiling finish materials tested in accordance with NFPA 286, and meeting the acceptance criteria of Section 803.1.1.1, shall be used where a Class A classification in accordance with ASTM E84 or UL 723 is required.

    TABLE 803.3—INTERIOR WALL AND CEILING FINISH REQUIREMENTS BY OCCUPANCYk Col2 Col3 Col4 Col5 Col6 Col7
    GROUP SPRINKLEREDl SPRINKLEREDl SPRINKLEREDl NONSPRINKLERED NONSPRINKLERED NONSPRINKLERED
    GROUP Interior exit stair-
    ways and ramps
    and exit passage-
    waysa, b    		 Corridors and enclosure
    for exit access stairways
    and ramps    		 Rooms and
    enclosed
    spacesc    		 Interior exit stair-
    ways and ramps and
    exit passagewaysa, b    		 Corridors and
    enclosure for exit
    access stairways and
    ramps    		 Rooms and
    enclosed
    spacesc
    A-1 and A-2 B B C A Ad Be
    A-3f, A-4, A-5 B B C A Ad C
    B, E, M, R-1, R-4 B Cm C A Bm C
    F C C C B C C
    H_, L_ B B Cg A A B
    I-1 B C C A B B
    I-3 A Aj C A A B
    I-4 B B Bh,
  • CBC § 720.2 High relevance — show source text

    720.2 Concealed installation. Insulating materials, where concealed as installed in buildings of any type of construction, shall have a flame spread index of not more than 25 and a smoke-developed index of not more than 450.

    Exception: Cellulosic fiber loose-fill insulation complying with the requirements of Section 720.6 shall not be required to meet a flame spread index requirement but shall be required to meet a smoke-developed index of not more than 450 when tested in accordance with CAN/ULC S102.2.

    720.2.1 Facings. Where such materials are installed in concealed spaces in buildings of Type III, IV or V construction, the flame spread and smoke-developed limitations do not apply to facings, coverings, and layers of reflective foil insulation that are installed behind and in substantial contact with the unexposed surface of the ceiling, wall or floor finish.

    Exception: All layers of single and multilayer reflective plastic core insulation shall comply with Section 2614.

    720.3 Exposed installation. Insulating materials, where exposed as installed in buildings of any type of construction, shall have a flame spread index of not more than 25 and a smoke-developed index of not more than 450.

    Exception: Cellulosic fiber loose-fill insulation complying with the requirements of Section 720.6 shall not be required to meet a flame spread index requirement but shall be required to meet a smoke-developed index of not more than 450 when tested in accordance with CAN/ULC S102.2.

    720.3.1 Attic floors. Exposed insulation materials installed on attic floors shall have a critical radiant flux of not less than 0.12 watt per square centimeter when tested in accordance with ASTM E970.

    720.4 Loose-fill insulation. Loose-fill insulation materials that cannot be mounted in the ASTM E84 or UL 723 apparatus without a screen or artificial supports shall comply with the flame spread and smoke-developed limits of Sections 720.2 and 720.3 when tested in accordance with CAN/ULC S102.2.

    Exception: Cellulosic fiber loose-fill insulation shall not be required to meet a flame spread index requirement when tested in accordance with CAN/ULC S102.2, provided that such insulation has a smoke-developed index of not more than 450 and complies with the requirements of Section 720.6.

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    FIRE AND SMOKE PROTECTION FEATURES

    720.5 Roof insulation. The use of combustible roof insulation not complying with Sections 720.2 and 720.3 shall be permitted in any type of construction provided that insulation is covered with approved roof coverings directly applied thereto.

    720.6 Cellulosic fiber loose-fill insulation and self-supported spray-applied cellulosic insulation. Cellulosic fiber loose-fill insulation and self-supported spray-applied cellulosic insulation shall comply with CPSC 16 CFR Parts 1209 and 1404. Each package of such insulating material shall be clearly labeled in accordance with CPSC 16 CFR Parts 1209 and 1404.

    720.7 Insulation and covering on pipe and tubing. Insulation and covering on pipe and tubing shall have a flame spread index of not more than 25 and a smoke-developed index of not more than 450.

  • CBC § 803.12 High relevance — show source text

    803.12 Facings or wood veneers intended to be applied on site over a wood substrate. Facings or veneers intended to be applied on site over a wood substrate shall comply with one of the following:

    1. The facing or veneer shall meet the criteria of Section 803.1.1.1 when tested in accordance with NFPA 286 using the product mounting system, including adhesive, as described in Section 5.9 of NFPA 286.
    2. The facing or veneer shall have a Class A, B or C flame spread index and smoke-developed index, based on the requirements of Table 803.13, in accordance with ASTM E84 or UL 723. Test specimen preparation and mounting shall be in accordance with ASTM E2404.

    803.13 Interior finish requirements based on occupancy. Interior wall and ceiling finish shall have a classification such that the flame spread index and smoke-developed index values are not higher than those corresponding to the classification specified in Table 803.13 for the group and location designated. Interior wall and ceiling finish materials tested in accordance with NFPA 286 and meeting the acceptance criteria of Section 803.1.1.1, shall be permitted to be used where a Class A classification in accordance with ASTM E84 or UL 723 is required.

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    INTERIOR FINISHES

    TABLE 803.13—INTERIOR WALL AND CEILING FINISH REQUIREMENTS BY OCCUPANCYk Col2 Col3 Col4 Col5 Col6 Col7
    GROUP SPRINKLEREDl SPRINKLEREDl SPRINKLEREDl NONSPRINKLERED NONSPRINKLERED NONSPRINKLERED
    GROUP Interior exit stair-
    ways and ramps
    and exit passage-
    waysa, b    		 Corridors and
    enclosure for exit
    access stairways
    and ramps    		 Rooms and
    enclosed spacesc    		 Interior exit stair-
    ways and ramps
    and exit passage-
    waysa, b    		 Corridors and
    enclosure for exit
    access stairways
    and ramps    		 Rooms and
    enclosed spacesc
    A-1 & A-2 B B C A Ad Be
    A-3f, A-4, A-5 B B C A Ad C
    B, E, M, R-1 B Cm C A B C
    R-4_n_ B C C A B B
    F C C C B C C
    H_, L_ B B Cg NP NP NP
    I-2_o_ B B Bh, i A A B
    I-3 A Aj B NP NP NP
    I-4 B B Bh,
  • CBC § 803.1.1 High relevance — show source text

    803.1.1 Interior wall and ceiling finish materials tested in accordance with NFPA 286. Interior wall and ceiling finish materials shall be classified in accordance with NFPA 286 and comply with Section 803.1.1.1. Materials complying with Section 803.1.1.1 shall be considered to also comply with the requirements of Class A.

    803.1.1.1 Acceptance criteria for NFPA 286. The interior finish shall comply with the following:

    1. During the 40 kW exposure, flames shall not spread to the ceiling.

    2. The flame shall not spread to the outer extremity of the sample on any wall or ceiling.

    3. Flashover, as defined in NFPA 286, shall not occur.

    4. The peak heat release rate throughout the test shall not exceed 800 kW.

    5. The total smoke released throughout the test shall not exceed 1,000 m [2] .

    803.1.2 Interior wall and ceiling finish materials tested in accordance with ASTM E84 or UL 723. Interior wall and ceiling finish materials shall be classified in accordance with ASTM E84 or UL 723. Such interior finish materials shall be grouped in the following classes in accordance with their flame spread and smoke-developed indices.

    Class A = Flame spread index 0–25; smoke-developed index 0–450.

    Class B = Flame spread index 26–75; smoke developed index 0–450.

    Class C = Flame spread index 76–200; smoke-developed index 0–450.

    Exception: Materials tested in accordance with Section 803.1.1 and as indicated in Sections 803.1.3 through 803.13.

    803.1.3 Interior wall and ceiling finish materials with different requirements. The materials indicated in Sections 803.2 through 803.13 shall be tested as indicated in the corresponding sections.

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    INTERIOR FINISHES

    803.2 Thickness exemption. Materials having a thickness less than 0.036 inch (0.9 mm) applied directly to the surface of walls or ceilings shall not be required to be tested.

    803.3 Heavy timber exemption. Exposed portions of building elements complying with the requirements for buildings of heavy timber construction in Section 602.4 or Section 2304.11 shall not be subject to interior finish requirements except in interior exit stairways, interior exit ramps, and exit passageways.

    803.4 Foam plastics. Foam plastics shall not be used as interior finish except as provided in Section 2603.9. This section shall apply both to exposed foam plastics and to foam plastics used in conjunction with a textile or vinyl facing or cover.

    803.5 Textile wall coverings. Where used as interior wall finish materials, textile wall coverings, including materials having woven or nonwoven, napped, tufted, looped or similar surface and carpet and similar textile materials, shall be tested in the manner intended for use, using the product-mounting system, including adhesive, and shall comply with the requirements of one of the following: Section 803.1.1, 803.5.1 or 803.5.2.

  • CBC § 803.7 High relevance — show source text

    803.7 Expanded vinyl wall coverings. Where used as interior wall finish materials, expanded vinyl wall coverings shall be tested in the manner intended for use, using the product-mounting system, including adhesive, and shall comply with the requirements of one of the following: Section 803.1.1, 803.5.1 or 803.5.2.

    803.8 Expanded vinyl ceiling coverings. Where used as interior ceiling finish materials, expanded vinyl ceiling coverings shall be tested in the manner intended for use, using the product mounting system, including adhesive, and shall comply with the requirements of Section 803.1.1 or 803.5.2.

    803.9 High-density polyethylene (HDPE) and polypropylene (PP). Where high-density polyethylene or polypropylene is used as an interior finish, it shall comply with Section 803.1.1.

    803.10 Site-fabricated stretch systems. Where used as interior wall or interior ceiling finish materials, site-fabricated stretch systems containing all three components described in the definition in Chapter 2 shall be tested in the manner intended for use, and shall comply with the requirements of Section 803.1.1 or with the requirements of Class A in accordance with Section 803.1.2. If the materials are tested in accordance with ASTM E84 or UL 723, specimen preparation and mounting shall be in accordance with ASTM E2573.

    803.11 Laminated products factory produced with a wood substrate. Laminated products factory produced with a wood substrate shall comply with one of the following:

    1. The laminated product shall meet the criteria of Section 803.1.1.1 when tested in accordance with NFPA 286 using the product-mounting system, including adhesive, as described in Section 5.8 of NFPA 286.
    2. The laminated product shall have a Class A, B, or C flame spread index and smoke-developed index, based on the requirements of Table 803.13, in accordance with ASTM E84 or UL 723. Test specimen preparation and mounting shall be in accordance with ASTM E2579.

    803.12 Facings or wood veneers intended to be applied on site over a wood substrate. Facings or veneers intended to be applied on site over a wood substrate shall comply with one of the following:

    1. The facing or veneer shall meet the criteria of Section 803.1.1.1 when tested in accordance with NFPA 286 using the product mounting system, including adhesive, as described in Section 5.9 of NFPA 286.
    2. The facing or veneer shall have a Class A, B or C flame spread index and smoke-developed index, based on the requirements of Table 803.13, in accordance with ASTM E84 or UL 723. Test specimen preparation and mounting shall be in accordance with ASTM E2404.

    803.13 Interior finish requirements based on occupancy. Interior wall and ceiling finish shall have a classification such that the flame spread index and smoke-developed index values are not higher than those corresponding to the classification specified in Table 803.13 for the group and location designated. Interior wall and ceiling finish materials tested in accordance with NFPA 286 and meeting the acceptance criteria of Section 803.1.1.1, shall be permitted to be used where a Class A classification in accordance with ASTM E84 or UL 723 is required.

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  • CBC § 1.1 High relevance — show source text

    – – – Class I or A, with a 0 25 FSR; Class II or B, with a 26 75 FSR; and Class III or C, with a 76 200 FSR. (Note: Some codes use Roman

    – numerals and others use letters.) The NFPA Life Safety Code also has a Class D (201 500 FSR) and Class E (over 500 FSR) interior finish.

    These classifications are typically used in modern building codes to restrict the rate of fire spread. Only the first three classifications are normally permitted, though not all classes of materials can be used in all places throughout a building. For example, the interior finish of building materials used in exits or in corridors leading to exits is more strictly regulated than materials used within private dwelling units.

    In general, inorganic archaic materials (e.g., bricks or tile) can be expected to be in Class I. Materials of whole wood are mostly Class II. Whole wood is defined as wood used in the same form as sawn from the tree. This is in contrast to the contemporary reconstituted wood products such as plywood, fiberboard, hardboard or particle board. If the organic archaic material is not whole wood, the flame spread classification could be well over 200 and thus would be particularly unsuited for use in exits and other critical locations in a building. Some plywoods and various wood fiberboards have flame spreads over 200. Although they can be treated with fire retardants to reduce their flame spread, it would be advisable to assume that all such products have a flame spread over 200 unless there is information to the contrary.

    Smoke Production

    The evaluation of smoke density is part of the ASTM E84 tunnel test. For the eight species of lumber shown in Table 1.1, the highest levels are 275–305 for Yellow Pine, but most of the others are less smoky than red oak which has an index of 100. The advent of plastics caused substantial increases in the smoke density values measured by the tunnel test. The ensuing limitation of the smoke production for wall and ceiling materials by the model building codes has been a reaction to the introduction of plastic materials. In general, cellulosic materials fall in the 50–300 range of smoke density which is below the general limitation of 450 adopted by many codes.

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    RESOURCE A—GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND ASSEMBLIES

    Degree of Combustibility

    The model building codes tend to define “noncombustibility” on the basis of having passed ASTM E136 or if the material is totally inorganic. The acceptance of gypsum wallboard as noncombustible is based on limiting paper thickness to not over [1] / 8 inch and a 0– 50 flame spread rating by ASTM E84. At times there were provisions to define a Class I or A material (0–25 FSR) as noncombustible, but this is not currently recognized by most model building codes.

    If there is any doubt whether or not an archaic material is noncombustible, it would be appropriate to send out samples for evaluation. If an archaic material is determined to be noncombustible according to ASTM E136, it can be expected that it will not contribute fuel to the fire.

    1.2 COMBUSTIBLE CONSTRUCTION TYPES

  • CBC § 3105.3 High relevance — show source text

    3105.3 Awnings and canopy materials. Awnings and canopies shall be provided with an approved covering that complies with one of the following:

    1. The fire propagation performance criteria of Test Method 1 or Test Method 2, as appropriate, of NFPA 701.
    2. Has a flame spread index not greater than 25 when tested in accordance with ASTM E84 or UL 723.
    3. Meets all of the following criteria when tested in accordance with NFPA 286: 3.1. During the 40 kW exposure, flames shall not spread to the ceiling. 3.2. Flashover, as defined in NFPA 286, shall not occur. 3.3. The flame shall not spread to the outer extremity of the sample on any wall or ceiling. 3.4. The peak heat release rate throughout the test shall not exceed 800 kW.

    All fabrics and all interior decorative fabrics or materials shall be flame resistant in accordance with the provisions set forth in CCR, Title 19, Division 1, Chapter 8. Tops and sidewalls shall be made either from fabric that has been flame resistant treated with an approved exterior chemical process by an approved application concern, or from inherently flame resistant fabric approved and listed by the State Fire Marshal (see CCR, Title 19, Division 1, Chapter 8).

    Exception: The fire propagation performance and flame spread index requirements shall not apply to awnings installed on detached one- and two-family dwellings.

    SECTION 3106—MARQUEES

    3106.1 General. Marquees shall comply with Sections 3106.2 through 3106.5 and other applicable sections of this code.

    3106.2 Thickness. The height or thickness of a marquee measured vertically from its lowest to its highest point shall be not greater than 3 feet (914 mm) where the marquee projects more than two-thirds of the distance from the lot line to the curb line, and shall be not greater than 9 feet (2743 mm) where the marquee is less than two-thirds of the distance from the lot line to the curb line.

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    SPECIAL CONSTRUCTION

    3106.3 Roof construction. Where the roof or any part thereof is a skylight, the skylight shall comply with the requirements of Chapter 24. Every roof and skylight of a marquee shall be sloped to downspouts that shall conduct any drainage from the marquee in such a manner so as not to spill over the sidewalk.

    3106.4 Location prohibited. Every marquee shall be so located as not to interfere with the operation of any exterior standpipe, and such that the marquee does not obstruct the clear passage of stairways or exit discharge from the building or the installation or maintenance of street lighting.

    3106.5 Construction. A marquee shall be supported entirely from the building and constructed of noncombustible materials. Marquees shall be designed as required in Chapter 16. Structural members shall be protected to prevent deterioration.

    SECTION 3107—SIGNS

    3107.1 General. Signs shall be designed, constructed and maintained in accordance with this code.

    SECTION 3108—TELECOMMUNICATION AND BROADCAST TOWERS

  • CBC § 803.1 High relevance — show source text

    INTERIOR FINISH, DECORATIVE MATERIALS AND FURNISHINGS

    SECTION 803—INTERIOR WALL AND CEILING FINISH IN EXISTING BUILDINGS

    803.1 General. The provisions of this section shall limit the allowable fire performance and smoke development of interior wall and ceiling finishes in existing buildings based on location and occupancy classification. Interior wall and ceiling finishes shall be classified in accordance with Section 803 of the California Building Code . Such materials shall be classified in accordance with NFPA 286, as indicated in Section 803.1.1, or in accordance with ASTM E84 or UL 723, as indicated in Section 803.1.2.

    Materials tested in accordance with Section 803.1.1 shall not be required to be tested in accordance with Section 803.1.2.

    803.1.1 Interior wall and ceiling finish materials tested in accordance with NFPA 286. Interior wall and ceiling finish materials shall be classified in accordance with NFPA 286 and tested in accordance with Section 803.1.1.1. Materials complying with Section 803.1.1.1 shall be considered to comply with the requirements of Class A specified in Section 803.1.2.

    803.1.1.1 Acceptance criteria for NFPA 286. The interior finish shall comply with the following:

    1. During the 40 kW exposure, flames shall not spread to the ceiling.

    2. The flame shall not spread to the outer extremity of the sample on any wall or ceiling.

    3. Flashover, as defined in NFPA 286, shall not occur.

    4. The peak heat release rate throughout the test shall not exceed 800 kW.

    5. The total smoke released throughout the test shall not exceed 1,000 m [2] .

    803.1.2 Interior wall and ceiling finish materials tested in accordance with ASTM E84 or UL 723. Interior wall and ceiling finishes shall be classified in accordance with ASTM E84 or UL 723. Such interior finish materials shall be grouped in the following classes in accordance with their flame spread and smoke-developed indices: Class A: Flame spread index 0–25; smoke-developed index 0–450. Class B: Flame spread index 26–75; smoke-developed index 0–450. Class C: Flame spread index 76–200; smoke-developed index 0–450.

    Exception: Materials tested in accordance with Section 803.1.1 and as indicated in Sections 803.1.3 through 803.15.

    803.1.3 Interior wall and ceiling finish materials with specific requirements. The materials indicated in Sections 803.4 through 803.15 shall be tested as indicated in the corresponding sections.

    803.2 Stability. Interior finish materials regulated by this chapter shall be applied or otherwise fastened in such a manner that such materials will not readily become detached where subjected to room temperatures of 200°F (93°C) for not less than 30 minutes.

    803.3 Interior finish requirements based on occupancy. Interior wall and ceiling finish shall have a flame spread index not greater than that specified in Table 803.3 for the group and location designated. Interior wall and ceiling finish materials tested in accordance with NFPA 286, and meeting the acceptance criteria of Section 803.1.1.1, shall be used where a Class A classification in accordance with ASTM E84 or UL 723 is required.

    |TABLE 803.

  • CBC § 1.1 High relevance — show source text

    Flame spread, smoke production and degree of combustibility are discussed in detail below. Test results for eight common species of lumber, published in an Underwriter’s Laboratories’ (UL) report (104), are noted in the following table:

    TABLE 1.1
    TUNNEL TEST RESULTS FOR EIGHT SPECIES OF LUMBER    		 Col2 Col3 Col4
    SPECIES OF LUMBER FLAME SPREAD FUEL CONTRIBUTED SMOKE DENSITY
    Western White Pine 75 50-60 50
    Northern White Pine 120–215 120–140 60–65
    Ponderosa Pine 80–215 120–135 100–110
    Yellow Pine 180–190 130–145 275–305
    Red Gum 140–155 125–175 40–60
    Yellow Birch 105–110 100–105 45–65
    Douglas Fir 65–100 50–80 10–100
    Western Hemlock 60—75 40—65 40—120

    Flame Spread

    The flame spread of interior finishes is most often measured by the ASTM E84 “tunnel test.” This test measures how far and how fast the flames spread across the surface of the test sample. The resulting flame spread rating (FSR) is expressed as a number on a continuous scale where cement-asbestos board is 0 and red oak is 100. (Materials with a flame spread greater than red oak have an FSR greater than 100.) The scale is divided into distinct groups or classes. The most commonly used flame spread classifications are:

    – – – Class I or A, with a 0 25 FSR; Class II or B, with a 26 75 FSR; and Class III or C, with a 76 200 FSR. (Note: Some codes use Roman

    – numerals and others use letters.) The NFPA Life Safety Code also has a Class D (201 500 FSR) and Class E (over 500 FSR) interior finish.

    These classifications are typically used in modern building codes to restrict the rate of fire spread. Only the first three classifications are normally permitted, though not all classes of materials can be used in all places throughout a building. For example, the interior finish of building materials used in exits or in corridors leading to exits is more strictly regulated than materials used within private dwelling units.

    In general, inorganic archaic materials (e.g., bricks or tile) can be expected to be in Class I. Materials of whole wood are mostly Class II. Whole wood is defined as wood used in the same form as sawn from the tree. This is in contrast to the contemporary reconstituted wood products such as plywood, fiberboard, hardboard or particle board. If the organic archaic material is not whole wood, the flame spread classification could be well over 200 and thus would be particularly unsuited for use in exits and other critical locations in a building. Some plywoods and various wood fiberboards have flame spreads over 200. Although they can be treated with fire retardants to reduce their flame spread, it would be advisable to assume that all such products have a flame spread over 200 unless there is information to the contrary.

    Smoke Production

  • CBC § 3.2 High relevance — show source text

    (1) A material that, in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Materials that are reported as passing ASTM E136 are considered noncombustible material.

    (2) Material having a structural base of noncombustible material as defined in item 1 above, with a surfacing material not over [1] ⁄ 8 of an inch (3.2 mm) thick that has a flame-spread index not higher than 50.

    Noncombustible does not apply to surface finish materials. Material required to be noncombustible for reduced clearances to flues, heating appliances, or other sources of high temperature shall refer to material in accordance with item 1

    42 2025 CALIFORNIA MECHANICAL CODE

    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    DEFINITIONS

    above. No material shall be classed as noncombustible that is subject to increase in combustibility or flame-spread index beyond the limits herein established, through the effects of age, moisture, or other atmospheric condition.

    Nonhazardous Process Piping (NPP). Production material piping or tubing conveying a liquid or gas that is not classified as hazardous production material piping.

    Nuisance. [HCD 1 & HCD 2] “Nuisance” shall mean any nuisance as defined in Health and Safety Code Section 17920(l).

    Notes:

    1. For applications subject to the Mobilehome Parks Act as referenced in Section 1.8.3.2.2 of this code, refer to Cal- ifornia Code of Regulations, Title 25, Division 1, Chap- ter 2 for the definition of “Nuisance.”

    2. For applications subject to the Special Occupancy Parks Act as referenced in Section 1.8.3.2.3 of this code, refer to California Code of Regulations, Title 25, Division 1, Chapter 2.2 for the definition of “Nuisance.”

    217.0 – O –

    Occupancy. The purpose for which a building or part thereof is used or intended to be used.

    Occupancy, Nontransient. Occupancy of a dwelling unit or sleeping unit for more than 30 days. [ASHRAE 62.1:3]

    Occupancy Classification. Classifications are defined in the building code. [HCD 1, HCD 2 & SFM] Whenever the term “Building Code” is used in this code, it shall mean the California Building Code, Title 24, Part 2.

    Occupational Exposure Limit (OEL). The timeweighted average (TWA) concentration for a normal 8-hour workday and a 40-hour workweek to which nearly all workers can be repeatedly exposed without adverse effect, based on the OSHA PEL, ACGIH TLV-TWA, TERA OARSWEEL, or consistent value. [ASHRAE 34:3]

    Occupiable Space. An enclosed space intended for human activities, excluding spaces that are intended to be occupied occasionally and for short periods of time, such as storage rooms, equipment rooms, and emergency exitways. [ASHRAE 62.1:3]

  • CBC § 803.13 Medium relevance — show source text

    1||X||||||||||||||||||||||| |Table 803.13|||X|||||||||||||||||||||| |804.1|||X|||||||||||||||||||||| |804.4|||X|||||||||||||||||||||| |804.4.1|||X|||||||||||||||||||||| |804.4.2|||X|||||||||||||||||||||| |804.4.3|||X|||||||||||||||||||||| |806.4|||X|||||||||||||||||||||| |806.6|||X||||||||||||||||||||||

    The state agency does not adopt sections identified by the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

    2025 CALIFORNIA BUILDING CODE 8-1

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

    8-2 2025 CALIFORNIA BUILDING CODE

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

    8 INTERIOR FINISHES

    User notes:

    About this chapter: Chapter 8 contains the performance requirements for controlling fire growth and smoke propagation within buildings by restricting interior finish and decorative materials. The provisions of this chapter require materials used as interior finishes and decorations to meet certain flame spread index or flame propagation criteria and smoke development criteria based on the relative fire hazard associated with the occupancy. The performance of the material is evaluated based on test standards.

    SECTION 801—SCOPE

    801.1 Scope. The provisions of this chapter shall govern the use of materials used as interior finishes, trim and decorative materials.

    [BSC-CG] See California Green Building Standards Code, Chapter 5, Division 5.5 for additional finish material pollutant control requirements.

    SECTION 802—GENERAL

    802.1 Interior wall and ceiling finish. The provisions of Section 803 shall limit the allowable fire performance and smoke development of interior wall and ceiling finish materials based on occupancy classification.

    802.2 Interior floor finish. The provisions of Section 804 shall limit the allowable fire performance of interior floor finish materials based on occupancy classification.

    [F] 802.3 Decorative materials and trim. Decorative materials and trim shall be restricted by combustibility, fire performance or flame propagation performance criteria in accordance with Section 806.

    802.4 Applicability. For buildings in flood hazard areas as established in Section 1612.3, interior finishes, trim and decorative materials below the elevation required by Section 1612 shall be flood-damage-resistant materials.

    802.5 Application. Combustible materials shall be permitted to be used as finish for walls, ceilings, floors and other interior surfaces of buildings.

    802.6 Windows. Show windows in the exterior walls of the first story above grade plane shall be permitted to be of wood or of unprotected metal framing.

    802.7 Foam plastics. Foam plastics shall not be used as interior finish except as provided in Section 803.4. Foam plastics shall not be used as interior trim except as provided in Section 806.6.1 or 2604.2. This section shall apply both to exposed foam plastics and to foam plastics used in conjunction with a textile or vinyl facing or cover.

    SECTION 803—WALL AND CEILING FINISHES

  • CBC § 5.5 Medium relevance — show source text

    [BSC-CG] See California Green Building Standards Code, Chapter 5, Division 5.5 for additional finish material pollutant control requirements.

    SECTION 802—GENERAL

    802.1 Interior wall and ceiling finish. The provisions of Section 803 shall limit the allowable fire performance and smoke development of interior wall and ceiling finish materials based on occupancy classification.

    802.2 Interior floor finish. The provisions of Section 804 shall limit the allowable fire performance of interior floor finish materials based on occupancy classification.

    [F] 802.3 Decorative materials and trim. Decorative materials and trim shall be restricted by combustibility, fire performance or flame propagation performance criteria in accordance with Section 806.

    802.4 Applicability. For buildings in flood hazard areas as established in Section 1612.3, interior finishes, trim and decorative materials below the elevation required by Section 1612 shall be flood-damage-resistant materials.

    802.5 Application. Combustible materials shall be permitted to be used as finish for walls, ceilings, floors and other interior surfaces of buildings.

    802.6 Windows. Show windows in the exterior walls of the first story above grade plane shall be permitted to be of wood or of unprotected metal framing.

    802.7 Foam plastics. Foam plastics shall not be used as interior finish except as provided in Section 803.4. Foam plastics shall not be used as interior trim except as provided in Section 806.6.1 or 2604.2. This section shall apply both to exposed foam plastics and to foam plastics used in conjunction with a textile or vinyl facing or cover.

    SECTION 803—WALL AND CEILING FINISHES

    803.1 General. Interior wall and ceiling finish materials shall be classified for fire performance and smoke development in accordance with Section 803.1.1 or 803.1.2, except as shown in Sections 803.1.3 through 803.15. Materials tested in accordance with Section 803.1.1 shall not be required to be tested in accordance with Section 803.1.2.

    803.1.1 Interior wall and ceiling finish materials tested in accordance with NFPA 286. Interior wall and ceiling finish materials shall be classified in accordance with NFPA 286 and comply with Section 803.1.1.1. Materials complying with Section 803.1.1.1 shall be considered to also comply with the requirements of Class A.

    803.1.1.1 Acceptance criteria for NFPA 286. The interior finish shall comply with the following:

    1. During the 40 kW exposure, flames shall not spread to the ceiling.

    2. The flame shall not spread to the outer extremity of the sample on any wall or ceiling.

    3. Flashover, as defined in NFPA 286, shall not occur.

    4. The peak heat release rate throughout the test shall not exceed 800 kW.

    5. The total smoke released throughout the test shall not exceed 1,000 m [2] .

    803.1.2 Interior wall and ceiling finish materials tested in accordance with ASTM E84 or UL 723. Interior wall and ceiling finish materials shall be classified in accordance with ASTM E84 or UL 723. Such interior finish materials shall be grouped in the following classes in accordance with their flame spread and smoke-developed indices.

    Class A = Flame spread index 0–25; smoke-developed index 0–450.

    Class B = Flame spread index 26–75; smoke developed index 0–450.

    Class C = Flame spread index 76–200; smoke-developed index 0–450.

Frequently asked questions

What test classification corresponds to “Class A”?

Class A is the ASTM E84 / UL‑723 group with flame‑spread index 0–25 and smoke‑developed index 0–450 per § 803.1.2; NFPA 286 results that meet § 803.1.1.1 may be accepted in lieu of Class A where the table requires Class A.

If my building is fully sprinklered, can I always use a lower class finish?

No — sprinkler protection often relaxes the required class (see the sprinklered columns in Table 803.13), but some locations or occupancies still require higher classes or are marked “NP” (not permitted). Always verify the specific occupancy row and table footnotes in § 803.13.

Can a manufacturer’s flame‑retardant treatment change the required class?

Yes—if the treated product’s test report shows the appropriate ASTM E84/UL‑723 class (or NFPA 286 acceptance when allowed), it can meet the class required by Table 803.13. Keep and present the test report to the AHJ. See § 803.1.2 and § 803.1.1 for the test options.

Are thin surface coverings exempt from testing?

Materials less than 0.036 in (0.9 mm) applied directly to walls / ceilings are exempt from testing per the thickness exemption in § 803.2 (see code text).

Where do I find the complete set of occupancy rows and footnotes?

See Table 803.13 in the CBC (Interior finish requirements by occupancy) and read the associated footnotes; the table is the controlling source for occupancy/location combinations. § 803.13 / Table 803.13 is the authoritative table.

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