CBC · California Building Code

What limits apply to combustible exterior wall coverings and how is ignition resistance tested?

In plain terms: California allows some combustible siding but only in limited amounts and heights, and where the code requires it the material must be laboratory‑tested to NFPA 268. If the test shows the siding resists ignition up to a certain radiant‑heat level, Table 1405.1.1.1.2 tells you how far it must be from neighboring buildings; if it's within 5 feet it must show zero sustained flaming on the NFPA 268 test. All of this is required and described in §§ 1405 and 1405.1.1.1 of the CBC .

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Last reviewed: July 5, 2026

What the code requires — 2-4 sentences

Combustible exterior wall coverings on buildings of Types I, II, III and IV‑HT are allowed only within the limits set in § 1405.1: area and height limits and required ignition‑resistance testing where permitted by § 1405.1.1. Where ignition‑resistance is required, the covering must be tested in accordance with NFPA 268 and meet the sustained‑flaming acceptance criteria for the applicable fire separation distance (§ 1405.1.1.1). For separations greater than 5 feet the minimum required separation is determined from Table 1405.1.1.1.2 based on the maximum tolerable incident radiant heat flux that does not produce sustained flaming (§ 1405.1.1.1.2) .

Requirements in detail

When combustible exterior wall coverings are permitted (area & height limits)

  • Area: If the fire separation distance is 5 feet (1524 mm) or less, combustible exterior wall coverings are limited to 10% of an exterior wall surface area (see § 1405.1) .
  • Height: Combustible exterior wall coverings are limited to 40 feet (12 192 mm) in height above grade plane unless an exception applies (§ 1405.1) .
  • Fire‑retardant‑treated wood exception: FRT wood complying with § 2303.2 for exterior use is not limited in wall surface area when the fire separation distance is 5 ft or less and may be used up to 60 ft in height regardless of separation (§ 1405.1, Exception 3) .

Code Reference summary

Decision factor Value / limit Code Reference
Max % of wall area (fire separation ≤ 5 ft) 10% § 1405.1
Max height above grade (general) 40 ft (12 192 mm) § 1405.1
FRT wood exception — area & height Unlimited area (≤5 ft), up to 60 ft height § 1405.1, Exception 3
Required ignition‑resistance test NFPA 268 § 1405.1.1.1
No sustained flaming (≤5 ft) Must not exhibit sustained flaming as defined in NFPA 268 § 1405.1.1.1.1
For separations >5 ft Use NFPA 268 reduced incident radiant flux; min separation from Table 1405.1.1.1.2 § 1405.1.1.1.2 and Table 1405.1.1.1.2

How ignition resistance is tested (NFPA 268 basics required by CBC)

  • The CBC specifically requires that combustible exterior wall coverings "shall be tested in accordance with NFPA 268" where ignition resistance is required (§ 1405.1.1.1) .
  • For walls with a fire separation distance of 5 ft or less, the tested material must show no sustained flaming per the NFPA 268 acceptance criteria (§ 1405.1.1.1.1) .
  • For separations greater than 5 ft, the material may be exposed in NFPA 268 to a reduced level of incident radiant heat flux; the maximum tolerable flux (the level that does not cause sustained flaming) determines the minimum allowable separation from Table 1405.1.1.1.2 (§ 1405.1.1.1.2) .

Table: Minimum fire separation (from Table 1405.1.1.1.2)

This is the decision table the code instructs you to use to determine the minimum separation based on the maximum tolerable incident radiant heat flux (kW/m2) measured under NFPA 268. Values shown are from Table 1405.1.1.1.2 (CBC) .

Minimum fire separation distance (feet) Tolerable incident radiant heat flux (kW/m2) Code Reference
5 12.5 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
6 11.8 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
7 11.0 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
8 10.3 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
9 9.6 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
10 8.9 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
11 8.3 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
12 7.7 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
13 7.2 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
14 6.7 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
15 6.3 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
16 5.9 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
17 5.5 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
18 5.2 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
19 4.9 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
20 4.6 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
21 4.4 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
22 4.1 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
23 3.9 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
24 3.7 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)
25 3.5 Table 1405.1.1.1.2 (§ 1405.1.1.1.2)

(Use the table by matching the tested maximum tolerable flux to the column of flux; the table row gives the minimum allowable separation in feet as directed by § 1405.1.1.1.2) .

Exceptions & special cases

  • Materials exempt from NFPA 268 testing per § 1405.1.1.1 Exception: wood or wood‑based products (i.e., traditional wood is not required by this paragraph to be tested under NFPA 268) .
  • Other exempted items: combustible materials covered with an exterior weather covering (other than vinyl siding) that comply with thickness requirements of Table 1404.2, and aluminum at a minimum thickness of 0.019 in (0.48 mm) are excepted from the NFPA 268 requirement (§ 1405.1.1.1, Exceptions 2 and 3) .
  • Where the separation is ≤ 5 ft, the acceptance criterion is stricter: no sustained flaming as defined in NFPA 268 (§ 1405.1.1.1.1) .
  • Fire‑retardant‑treated wood has its own allowances (no area limit at ≤ 5 ft and permitted up to 60 ft high) as noted in § 1405.1 Exception 3 .

Common mistakes

  • Treating NFPA 268 as optional. The CBC explicitly requires NFPA 268 testing where ignition resistance is required (§ 1405.1.1.1) .
  • Applying the Table for ≤ 5 ft distances. For 5 ft (and less) the requirement is "no sustained flaming" per NFPA 268 — you do not use the table flux/distance mapping for that case (§ 1405.1.1.1.1) .
  • Forgetting exceptions (e.g., aluminum ≥ 0.019 in thickness or compliant weather coverings) that exempt a material from NFPA 268 testing (§ 1405.1.1.1 exceptions) .
  • Reading the table values as material properties rather than as the maximum tolerable incident radiant heat flux measured in NFPA 268 testing — the table ties a measured flux to a required minimum separation (§ 1405.1.1.1.2 and Table 1405.1.1.1.2) .
  • Overlooking construction‑type limits and special system exceptions (MCM, EIFS, HPL, etc.) listed in § 1405.1 exceptions; some claddings are governed by their own sections (§ 1406, § 1407, § 1408) .

Worked example — concrete scenario

Scenario: You propose to use a combustible composite cladding on a Type III apartment building façade. The assembly is NFPA 268 tested and the report shows the cladding does not exhibit sustained flaming up to an incident radiant heat flux of 8.3 kW/m2.

Step 1 — Is the cladding allowed at all? Type III is one of the construction types where combustible exterior wall coverings are permitted but subject to limits in § 1405.1 .

Step 2 — Check separation rule. Because the testing produced a maximum tolerable flux of 8.3 kW/m2, use Table 1405.1.1.1.2: 8.3 kW/m2 corresponds to a minimum fire separation distance of 11 feet (Table 1405.1.1.1.2) .

Step 3 — Check ≤5 ft rule. If your actual fire separation to the adjacent property or building is 5 ft or less, the table is not applied — instead the material must demonstrate no sustained flaming per NFPA 268 (§ 1405.1.1.1.1). If your separation is 5 ft or less and the test showed no sustained flaming, it could be acceptable; if the test shows any sustained flaming it is not permitted at ≤5 ft (§ 1405.1.1.1.1) .

Step 4 — Other limits. Ensure the combustible covering does not exceed 10% of the wall area if the separation is ≤5 ft, and that the height limit (40 ft) is not exceeded unless an exception applies (§ 1405.1) .

Conclusion for this scenario: With a tested tolerance of 8.3 kW/m2 you must have at least an 11 ft fire separation to meet § 1405.1.1.1.2 (if separation > 5 ft); if the actual separation is ≤ 5 ft you must have a NFPA 268 result showing no sustained flaming (§ 1405.1.1.1.1) .

Related provisions

  • § 1405.1 — Combustible exterior wall coverings (area/height limits, exceptions)
  • § 1405.1.1.1 — Ignition resistance; NFPA 268 required where applicable (exceptions listed)
  • § 1405.1.1.1.1 — Requirement for no sustained flaming where fire separation ≤ 5 ft (NFPA 268 criterion)
  • § 1405.1.1.1.2 and Table 1405.1.1.1.2 — For separations > 5 ft: use NFPA 268 reduced flux and table to find minimum separation
  • § 1405.1.3 — Fireblocking requirements where combustible exterior covering creates a concealed space
  • § 1402.5 — Vertical and lateral flame propagation and NFPA 285 considerations for assemblies containing combustible cladding components

Code references

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

  • CBC § 1404.6. High relevance — show source text
    1. Wood veneers shall comply with Section 1404.6.

    1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

    Exceptions:

    1. Wood or wood-based products.
    2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
    3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

    1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

    1405.1.1.1.2 Fire separation greater than 5 feet. For fire separation distances greater than 5 feet (1524 mm), any exterior wall covering shall be permitted that has been exposed to a reduced level of incident radiant heat flux in accordance with the NFPA 268 test method without exhibiting sustained flaming. The minimum fire separation distance required for the exterior wall covering shall be determined from Table 1405.1.1.1.2 based on the maximum tolerable level of incident radiant heat flux that does not cause sustained flaming of the exterior wall covering.

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    TABLE 1405.1.1.1.2—MINIMUM FIRE SEPARATION FOR COMBUSTIBLE EXTERIOR WALL COVERINGS Col2
    FIRE SEPARATION DISTANCE (feet) TOLERABLE LEVEL INCIDENT RADIANT HEAT ENERGY (kW/m2)
    5 12.5
    6 11.8
    7 11.0
    8 10.3
    9 9.6
    10 8.9
    11 8.3
    12 7.7
    13 7.2
    14 6.7
    15 6.3
    16 5.9
    17 5.5
    18 5.2
    19 4.9
    20 4.6
    21 4.4
    22 4.1
    23 3.9
    24 3.7
    25 3.5
    For SI: 1 foot = 304.8 mm, 1 Btu/H2 × °F = 0.0057 kW/m2 × K. For SI: 1 foot = 304.8 mm, 1 Btu/H2 × °F = 0.0057 kW/m2 × K.

    1405.1.2 Location. Combustible exterior wall coverings located along the top of exterior walls shall be completely backed up by the exterior wall and shall not extend over or above the top of the exterior wall.

  • CBC § 1404.19 High relevance — show source text

    [BS] 1404.19 Fiber-mat reinforced cementitious backer units. Fiber-mat reinforced cementitious backer units shall be permitted on exterior walls and shall meet the requirements of Section 1404.19.1.

    [BS] 1404.19.1 Installation. Installation of fiber-mat reinforced cementitious backer units used as an exterior substrate for the application of exterior finish materials shall be in accordance with backer unit manufacturer’s installation instructions. Panels shall be installed using corrosion-resistant fasteners. Finish materials shall be installed in accordance with approved finish material manufacturer’s instructions.

    SECTION 1405—COMBUSTIBLE MATERIALS ON THE EXTERIOR SIDE OF EXTERIOR WALLS

    1405.1 Combustible exterior wall coverings. Combustible exterior wall coverings shall comply with this section.

    Exception: Plastics complying with Chapter 26.

    1405.1.1 Types I, II, III and IV-HT construction. On buildings of Types I, II, III and IV-HT construction, exterior wall coverings shall be permitted to be constructed of combustible materials, complying with the following limitations:

    1. Combustible exterior wall coverings shall not exceed 10 percent of an exterior wall surface area where the fire separation distance is 5 feet (1524 mm) or less.
    2. Combustible exterior wall coverings shall be limited to 40 feet (12 192 mm) in height above grade plane. Exceptions:
    3. Metal composite material (MCM) systems complying with Section 1406.
    4. Exterior insulation and finish systems (EIFS) complying with Section 1407.
    5. High-pressure decorative exterior-grade compact laminate (HPL) systems complying with Section 1408.
    6. Exterior wall coverings containing foam plastic insulation complying with Section 2603.
    7. Combustible exterior wall coverings constructed of fire-retardant-treated wood complying with Section 2303.2 for exterior installation shall not be limited in wall surface area where the fire separation distance is 5 feet (1524 mm) or less and shall be permitted up to 60 feet (18 288 mm) in height above grade plane regardless of the fire separation distance.
    8. Wood veneers shall comply with Section 1404.6.

    1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

    Exceptions:

    1. Wood or wood-based products.
    2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
    3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

    1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

  • CBC § 2303.2 High relevance — show source text
    1. Combustible exterior wall coverings shall be limited to 40 feet (12 192 mm) in height above grade plane. Exceptions:
    2. Metal composite material (MCM) systems complying with Section 1406.
    3. Exterior insulation and finish systems (EIFS) complying with Section 1407.
    4. High-pressure decorative exterior-grade compact laminate (HPL) systems complying with Section 1408.
    5. Exterior wall coverings containing foam plastic insulation complying with Section 2603.
    6. Combustible exterior wall coverings constructed of fire-retardant-treated wood complying with Section 2303.2 for exterior installation shall not be limited in wall surface area where the fire separation distance is 5 feet (1524 mm) or less and shall be permitted up to 60 feet (18 288 mm) in height above grade plane regardless of the fire separation distance.
    7. Wood veneers shall comply with Section 1404.6.

    1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

    Exceptions:

    1. Wood or wood-based products.
    2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
    3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

    1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

    1405.1.1.1.2 Fire separation greater than 5 feet. For fire separation distances greater than 5 feet (1524 mm), any exterior wall covering shall be permitted that has been exposed to a reduced level of incident radiant heat flux in accordance with the NFPA 268 test method without exhibiting sustained flaming. The minimum fire separation distance required for the exterior wall covering shall be determined from Table 1405.1.1.1.2 based on the maximum tolerable level of incident radiant heat flux that does not cause sustained flaming of the exterior wall covering.

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  • CBC § 14-15 High relevance — show source text

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    [BS] 1404.18 Polypropylene siding. Polypropylene siding conforming to the requirements of this section and complying with Section 1403.11 shall be limited to exterior walls located in areas where the basic wind speed, V, specified in Chapter 16 does not exceed 100 miles per hour (45 m/s) and the building height is less than or equal to 40 feet (12 192 mm) in Exposure C. Where construction is located in areas where the basic wind speed, V, exceeds 100 miles per hour (45 m/s), or building heights are in excess of 40 feet (12 192 mm), tests or calculations indicating compliance with Chapter 16 shall be submitted.

    [BS] 1404.18.1 Installation. Polypropylene siding and accessories shall be installed over and attached to wood structural panel sheathing with nailable substrate not less than [7] / 16 inch (11.1 mm) in thickness or other substrate suitable for mechanical fasteners in accordance with the approved manufacturer’s instructions.

    [BS] 1404.18.2 Fastener requirements. Unless otherwise specified in the approved manufacturer’s instructions, nails shall be corrosion resistant, with a minimum 0.120-inch (3 mm) shank and a minimum 0.313-inch (8 mm) head diameter. Nails shall be not less than 1 [1] / 4 inches (32 mm) long or as necessary to penetrate sheathing or nailable substrate not less than [3] / 4 inch (19.1 mm). Where the nail fully penetrates the sheathing or nailable substrate, the end of the fastener shall extend not less than [1] / 4 inch (6.4 mm) beyond the opposite face of the sheathing or nailable substrate. Spacing of fasteners shall be installed in accordance with the approved manufacturer’s instructions.

    [BS] 1404.19 Fiber-mat reinforced cementitious backer units. Fiber-mat reinforced cementitious backer units shall be permitted on exterior walls and shall meet the requirements of Section 1404.19.1.

    [BS] 1404.19.1 Installation. Installation of fiber-mat reinforced cementitious backer units used as an exterior substrate for the application of exterior finish materials shall be in accordance with backer unit manufacturer’s installation instructions. Panels shall be installed using corrosion-resistant fasteners. Finish materials shall be installed in accordance with approved finish material manufacturer’s instructions.

    SECTION 1405—COMBUSTIBLE MATERIALS ON THE EXTERIOR SIDE OF EXTERIOR WALLS

    1405.1 Combustible exterior wall coverings. Combustible exterior wall coverings shall comply with this section.

    Exception: Plastics complying with Chapter 26.

    1405.1.1 Types I, II, III and IV-HT construction. On buildings of Types I, II, III and IV-HT construction, exterior wall coverings shall be permitted to be constructed of combustible materials, complying with the following limitations:

    1. Combustible exterior wall coverings shall not exceed 10 percent of an exterior wall surface area where the fire separation distance is 5 feet (1524 mm) or less.
    2. Combustible exterior wall coverings shall be limited to 40 feet (12 192 mm) in height above grade plane. Exceptions:
  • CBC § 504.5.1 High relevance — show source text

    Such material shall extend from the top of the foundation to the underside of the roof sheathing.

    504.5.1 Flashing. A minimum of 6 inches (152 mm) of metal flashing or noncombustible material applied vertically on the exterior of the wall shall be installed at the ground, decking and roof intersections.

    504.5.2 Exterior wall coverings. Exterior wall coverings shall comply with one or more of the following requirements:

    1. Noncombustible material.

    2. Ignition-resistant building material labeled for exterior use. 3. Fire-retardant-treated wood labeled for exterior use and complying with the requirements of Section 2303.2 of the Califor- nia Building Code. 4. Fire-retardant-treated wood shingles and shakes which have been qualified in accordance with Section 1505.6 of the Cali- fornia Building Code for use as “Class B” roof covering shall be an acceptable alternative wall covering material where installed over solid sheathing.

    Exception: Exterior wall coverings which are a component of an approved wall assembly complying with Section 504.5.

    504.5.2.1 Extent of exterior wall covering. Where provided, exterior wall coverings shall extend from the top of the foundation to the roof, and terminate at 2-inch (50.8 mm) nominal solid wood blocking between rafters at all roof overhangs, or in the case of enclosed eaves, terminate at the enclosure.

    504.6 Underfloor enclosure. Buildings or structures shall have underfloor areas enclosed to the ground with exterior walls in accordance with Section 504.5.

    Exception: Complete enclosure shall not be required where the underside of exposed floors and exposed structural columns, beams and supporting walls are protected as required for exterior 1-hour fire-resistance-rated construction or heavy timber construction or fire-retardant-treated wood. The fire-retardant-treated wood shall be labeled for exterior use and meet the requirements of Section 2303.2 of the California Building Code .

    504.7 Projections . Unenclosed accessory structures attached to buildings with habitable spaces and projections, other than decks, shall be heavy timber construction or constructed of one of the following:

    1. Noncombustible materials.

    2. Fire-retardant-treated wood identified for exterior use and meeting the requirements of Section 2303.2 of the California Building Code .

    3. Ignition-resistant building materials in accordance with Section 503.2. 4. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.

    5. One layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind the exterior covering on the underside of the ceiling. 6. The exterior portion of a 1-hour fire-resistance-rated exterior assembly, as tested in accordance with ASTM E119 or UL 263, applied to the underside of the ceiling assembly, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual. 7. The underside of a floor projection assembly that meets the performance criteria in Section 504.7.2 when tested in accordance with the test procedures set forth in ASTM E2957.

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  • CBC § 1409.1 High relevance — show source text

    SECTION 1409—INSULATED METAL PANEL (IMP)

    1409.1 General. The provisions of this section, in addition to the other applicable requirements of this chapter and Chapter 16, shall govern the materials, construction and quality of insulated metal panels (IMP) for use as exterior walls and exterior wall coverings.

    1409.2 Structural design. Structural design of IMP systems shall be in accordance with this section.

    1409.2.1 IMP systems used as exterior walls. IMP systems used as exterior walls shall be designed and constructed to resist design loads in accordance with applicable provisions of Chapter 16.

    1409.2.2 IMP systems used as exterior wall coverings. IMP systems used as exterior wall covering systems shall be designed and constructed to resist wind loads as required by Section 1609.

    1409.2.3 Approval. Results of approved tests or engineering analyses shall be submitted to the building official to verify compliance with the applicable requirements of Chapter 16.

    1409.3 Weather resistance. IMP systems shall comply with Section 1402 and shall be designed and constructed to resist wind and rain in accordance with this section and the manufacturer’s installation instructions.

    1409.4 Durability. IMP systems shall be constructed of approved materials that maintain the performance characteristics required in Section 1402 for the duration of use.

    1409.5 Fire-resistance rating. Evidence of the required fire-resistance rating of IMP systems shall be in accordance with this section.

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    1409.5.1 IMP used as exterior walls. In all types of construction where IMP systems are used as exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the wall achieves the required fire-resistance rating.

    1409.5.2 IMP used as exterior wall coverings. In all types of construction where IMP systems are used as exterior wall coverings on exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the required fire-resistance rating is maintained.

    Exception: IMP systems not containing combustible insulation, which are installed on the outer surface of a fire-resistance rated exterior wall in a manner such that the attachments do not penetrate to the entire exterior wall assembly.

    1409.6 IMP systems with noncombustible core insulation. IMP with noncombustible core insulation shall comply with Sections 1409.1 through 1409.5. Combustibility shall be determined in accordance with Section 703.3.

    1409.7 IMP systems with combustible core insulation. IMP systems with combustible core insulation shall comply with Sections 1409.1 through 1409.5 and this section. Combustibility shall be determined in accordance with Section 703.3.

  • CBC § 2.1. High relevance — show source text

    The exterior wall design shall be considered to resist wind-driven rain where the results of testing, in accordance with ASTM E331, indicate that water did not penetrate control joints in the exterior wall, joints at the perimeter of openings or intersections of terminations with dissimilar materials.

    2.1. Exterior wall test assemblies shall include not fewer than one opening, one control joint, one wall/eave interface and one wall sill. Tested openings and penetrations shall be representative of the intended end-use configuration. 2.2. Exterior wall test assemblies shall be not less than 4 feet by 8 feet (1219 mm by 2438 mm) in size. 2.3. Exterior wall test assemblies shall be tested at a minimum differential pressure of 6.24 pounds per square foot (0.297 kN/m [2] ). 2.4. Exterior wall test assemblies shall be subjected to a minimum test exposure duration of 2 hours. 3. Exterior insulation and finish systems (EIFS) complying with Section 1407.4.1.

    1402.2.1 [BSC-CG] See California Green Building Standards Code, Chapter 5, Division 5.4 for additional weather protection requirements.

    [BS] 1402.3 Wind resistance. Exterior walls, exterior wall coverings, exterior soffits and fascias, and the associated openings, shall be designed and constructed to resist safely the superimposed loads required by Chapter 16.

    [BS] 1402.3.1 Attachments through exterior insulation. Where exterior wall coverings are attached to the building structure through exterior continuous insulation, furring and attachments through the exterior insulation shall be designed to resist design loads determined in accordance with Chapter 16, including support of cladding weight as applicable. Exterior wall coverings attached to the building structure through foam plastic insulating sheathing shall comply with the attachment requirements of Section 1404.5.1, 1404.5.2 or 1404.5.3.

    1402.4 Fire resistance. Exterior walls shall be fire-resistance rated as required by other sections of this code with opening protection as required by Chapter 7.

    1402.5 Vertical and lateral flame propagation. Exterior walls on buildings of Type I, II, III and IV construction that contain a combustible exterior wall covering, combustible insulation or a combustible water-resistive barrier shall comply with Sections 1402.5.1 through 1402.5.5, as applicable. Where compliance with NFPA 285 and associated acceptance criteria is required in Sections 1402.5.1 through 1402.5.5, the exterior wall assembly shall be tested in accordance with and comply with the acceptance criteria of NFPA 285.

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    1402.5.1 Combustible water-resistive barrier. Exterior walls containing a combustible water-resistive barrier shall comply with Section 1402.6.

    1402.5.2 Metal composite material (MCM). Exterior walls containing metal composite material (MCM) systems shall comply with Section 1406.

    1402.5.3 Exterior insulation and finish system (EIFS). Exterior walls containing an exterior insulation and finish system (EIFS) shall comply with Section 1407.

  • CBC § 0.125 High relevance — show source text

    Exception: Materials having a structural base of noncombustible material as determined in accordance with ASTM E136, or with ASTM E2652 using the acceptance criteria prescribed by ASTM E136, and a surfacing of not more than 0.125 inch (3.18 mm) in thick- ness having a flame spread index not greater than 50 when tested in accordance with ASTM E84 or UL 723 shall be acceptable as noncombustible.

    SECTION 502— RESERVED

    SECTION 503—IGNITION-RESISTANT CONSTRUCTION AND MATERIAL

    503.1 General. Buildings and structures hereafter constructed, modified or relocated into or within wildland-urban interface areas shall meet the construction requirements in accordance with Chapter 5 . Materials required to be ignition-resistant building materials shall comply with the requirements of Section 503.2.

    Exceptions:

    1. New accessory buildings and miscellaneous structures complying with Section 504.11. 2. Additions to and remodels of buildings originally constructed prior to July 1, 2008. 3. Group C occupancy special buildings conforming to the limitations specified in Section 450.4.1 of the California Building Code.

    503.2 Ignition-resistant building material. Ignition-resistant building materials shall be designed for exterior use and weather expo- sure and shall comply with any one of the requirements in Section 503.2.1 through 503.2.4.3.3 .

    503.2.1 Noncombustible material. Noncombustible material shall comply with the requirements in Section 501.4 .

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    SPECIAL BUILDING CONSTRUCTION REGULATIONS

    503.2.2 Fire-retardant-treated wood. Fire-retardant-treated wood shall be identified for exterior use and shall meet the requirements of Section 2303.2 of the California Building Code .

    503.2.3 Fire-retardant-treated wood roof coverings. Roof assemblies containing fire-retardant-treated wood shingles and shakes shall comply with the requirements of Section 1505.6 of the California Building Code and shall be classified as Class A roof assemblies as required in Section 1505.2 of the California Building Code .

    503.2.4 Other ignition-resistant building material. Material shall be tested on the front and back faces in accordance with the extended ASTM E84 or UL 723 test, for a total test period of 30 minutes, or with the ASTM E2768 test. The materials shall bear identification showing the fire test results. Panel products shall be tested with a ripped or cut longitudinal gap of [1] / 8 inch (3.2 mm). The materials, when tested in accordance with the test procedures set forth in ASTM E84 or UL 723 for a test period of 30 minutes, or with ASTM E2768, shall comply with Sections 503.2.4.1 through 503.2.4.3.

    Exception: Materials composed of a combustible core and a noncombustible exterior covering made from either aluminum at a minimum 0.019 inch (0.48 mm) thickness or corrosion-resistant steel at a minimum 0.0149 inch (0.38 mm) thickness shall not be required to be tested with a ripped or cut longitudinal gap.

  • CBC § 1405.1.3 High relevance — show source text

    1405.1.3 Fireblocking. Where the combustible exterior wall covering is furred out from the exterior wall and forms a solid surface, the distance between the back of the exterior wall covering and the exterior wall shall not exceed 1 [5] / 8 inches (41 mm). The concealed space thereby created shall be fireblocked in accordance with Section 718. Exception: The distance between the back of the exterior wall covering and the exterior wall shall be permitted to exceed 1 [5] / 8 inches (41 mm) where the concealed space is not required to be fireblocked by Section 718.

    SECTION 1406—METAL COMPOSITE MATERIAL (MCM)

    1406.1 General. The provisions of this section shall govern the materials, construction and quality of metal composite material (MCM) for use as exterior wall coverings in addition to other applicable requirements of Chapters 14 and 16.

    1406.2 Exterior wall covering. MCM used as exterior wall covering or as elements of balconies and similar projections and bay and oriel windows to provide cladding or weather resistance shall comply with Sections 1406.4 through 1406.13.

    1406.3 Architectural trim and embellishments. MCM used as architectural trim or embellishments shall comply with Sections 1406.7 through 1406.13.

    [BS] 1406.4 Structural design. MCM systems shall be designed and constructed to resist wind loads as required by Chapter 16 for components and cladding.

    1406.5 Approval. Results of approved tests or an engineering analysis shall be submitted to the building official to verify compliance with the requirements of Chapter 16 for wind loads.

    1406.6 Weather resistance. MCM systems shall comply with Section 1402 and shall be designed and constructed to resist wind and rain in accordance with this section and the manufacturer’s installation instructions.

    1406.7 Durability. MCM systems shall be constructed of approved materials that maintain the performance characteristics required in Section 1406 for the duration of use.

    1406.8 Fire-resistance rating. Where MCM systems are used on exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the required fire-resistance rating is maintained.

    Exception: MCM systems that are part of an exterior wall assembly not containing foam plastic insulation and are installed on the outer surface of a fire-resistance-rated exterior wall in a manner such that the attachments do not penetrate through the entire exterior wall assembly, shall not be required to comply with this section.

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    EXTERIOR WALLS

    1406.9 Surface-burning characteristics. Unless otherwise specified, MCM shall have a flame spread index of 75 or less and a smokedeveloped index of 450 or less when tested in the maximum thickness intended for use in accordance with ASTM E84 or UL 723.

  • CBC § 1409.5 High relevance — show source text

    1409.5 Fire-resistance rating. Evidence of the required fire-resistance rating of IMP systems shall be in accordance with this section.

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    EXTERIOR WALLS

    1409.5.1 IMP used as exterior walls. In all types of construction where IMP systems are used as exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the wall achieves the required fire-resistance rating.

    1409.5.2 IMP used as exterior wall coverings. In all types of construction where IMP systems are used as exterior wall coverings on exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the required fire-resistance rating is maintained.

    Exception: IMP systems not containing combustible insulation, which are installed on the outer surface of a fire-resistance rated exterior wall in a manner such that the attachments do not penetrate to the entire exterior wall assembly.

    1409.6 IMP systems with noncombustible core insulation. IMP with noncombustible core insulation shall comply with Sections 1409.1 through 1409.5. Combustibility shall be determined in accordance with Section 703.3.

    1409.7 IMP systems with combustible core insulation. IMP systems with combustible core insulation shall comply with Sections 1409.1 through 1409.5 and this section. Combustibility shall be determined in accordance with Section 703.3.

    1409.7.1 Surface-burning characteristics. Unless otherwise specified in this section, a combustible core 4 inches (102 mm) or less in thickness shall have a flame spread index of 75 or less and a smoke-developed index of 450 or less when tested in the maximum thickness intended for use in accordance with ASTM E84 or UL 723. For thicknesses greater than 4 inches (102 mm), the combustible core shall have a flame spread index of 75 or less and a smoke-developed index of 450 or less at 4 inches (102 mm) in thickness and the IMP approved based on testing in accordance with Section 1409.7.2.2 at the maximum IMP thickness intended for use.

    1409.7.1.1 Foam plastic core. For IMP having a core insulation composed of foam plastic, the insulation core shall comply with Section 2603.3.

    1409.7.2 Thermal barrier. Unless otherwise specified in this section, IMP with a combustible core shall be separated from the interior of a building by an approved thermal barrier consisting of [1] / 2 -inch (12.7 mm) gypsum wallboard or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275.

    1409.7.2.1 Foam plastic core. For IMP having a foam plastic core, use with the thermal barrier prescribed in Section 1409.7.2 shall be in accordance with Section 2603.4 unless special approval is obtained on the basis of Section 2603.9.

  • CBC § 703.1 High relevance — show source text

    SECTION 703—FIRE-RESISTANCE RATINGS AND FIRE TESTS

    703.1 Scope. Materials prescribed herein for fire resistance shall conform to the requirements of this chapter.

    703.2 Fire resistance. The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with Section 703.2.1 or 703.2.2 without the use of automatic sprinklers or any other fire suppression system being incorporated, or in accordance with Section 703.2.3.

    703.2.1 Tested assemblies. A fire-resistance rating of building elements, components or assemblies shall be determined by the test procedures set forth in ASTM E119 or UL 263. The fire-resistance rating of penetrations and fire-resistant joint systems shall be determined in accordance with Sections 714 and 715, respectively.

    703.2.1.1 Nonsymmetrical wall construction. Interior walls and partitions of nonsymmetrical construction shall be tested with both faces exposed to the furnace, and the assigned fire-resistance rating shall be the shortest duration obtained from the two tests conducted in compliance with ASTM E119 or UL 263. Where evidence is furnished to show that the wall was tested with the least fire-resistant side exposed to the furnace, subject to acceptance of the building official, the wall need not be subjected to tests from the opposite side (see Section 705.5 for exterior walls).

    703.2.1.2 Combustible components. Combustible aggregates are permitted in gypsum and Portland cement concrete mixtures for fire-resistance-rated construction. Any component material or admixture is permitted in assemblies if the resulting tested assembly meets the fire-resistance test requirements of this code.

    703.2.1.3 Restrained classification. Fire-resistance-rated assemblies tested under ASTM E119 or UL 263 shall not be considered to be restrained unless evidence satisfactory to the building official is furnished by the registered design professional showing that the construction qualifies for a restrained classification in accordance with ASTM E119 or UL 263. Restrained construction shall be identified on the construction documents.

    703.2.1.4 Supplemental features. Where materials, systems or devices that have not been tested as part of a fire-resistancerated assembly are incorporated into the building element, component or assembly, sufficient data shall be made available to the building official to show that the required fire-resistance rating is not reduced.

    703.2.1.5 Exterior bearing walls. In determining the fire-resistance rating of exterior bearing walls, compliance with the ASTM E119 or UL 263 criteria for unexposed surface temperature rise and ignition of cotton waste due to passage of flame or gases is required only for a period of time corresponding to the required fire-resistance rating of an exterior nonbearing wall with the same fire separation distance, and in a building of the same group. Where the fire-resistance rating determined in accordance with this exception exceeds the fire-resistance rating determined in accordance with ASTM E119 or UL 263, the fire exposure time period, water pressure and application duration criteria for the hose stream test of ASTM E119 or UL 263 shall be based on the fire-resistance rating determined in accordance with this section.

    703.2.2 Analytical methods. The fire resistance of building elements, components or assemblies established by an analytical method shall be by any of the methods listed in this section, based on the fire exposure and acceptance criteria specified in ASTM E119 or UL 263.

    1. Fire-resistance designs documented in approved sources.
    2. Prescriptive designs of fire-resistance-rated building elements, components or assemblies as prescribed in Section 721.
  • CBC § 2.1 High relevance — show source text
    agency BSC BSC-
    CG    		 SFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC
    Adopting agency BSC BSC-
    CG    		 SFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6
    Adopt entire chapter X X X X X
    Adopt entire chapter as
    amended (amended sections
    listed below)    		 X X X X X X X
    Adopt only those sections
    that are listed below    		 X X X
    Chapter / Section
    1401 X
    1402 X
    1402.2.1 X
    1403 X
    1404 X
    1404.1.2 X X X X X X X
    1404.3.3 X
    1405 X
    1406 X
    1407 X
    1408 X
    1411 X
    1412 X
    1413 X X X X X X X

    The state agency does not adopt sections identified with 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.

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    14 EXTERIOR WALLS

    User notes:

    About this chapter: Chapter 14 addresses requirements for exterior walls of buildings. Minimum standards for wall covering materials, such as material performance and fire resistance, installation of wall coverings and the ability of the wall to provide weather protection are provided. This chapter also contains limitations on the areas and heights of combustible wall coverings based on fire separation distances, radiant heat exposure and surface burning characteristics.

Frequently asked questions

Do I always need an NFPA 268 test report to use combustible cladding?

If the cladding is subject to § 1405.1.1 (i.e., permitted combustible exterior wall coverings) and not covered by an exception, the CBC requires NFPA 268 testing per § 1405.1.1.1. Exceptions (wood, certain weather‑covered materials, specified aluminum thickness) are listed in that section .

What does "no sustained flaming" mean for a ≤5 ft separation?

"No sustained flaming" is the NFPA 268 acceptance criterion applied for fire separations of 5 ft or less; the tested specimen must not exhibit sustained flaming as defined in NFPA 268 to comply with § 1405.1.1.1.1 .

How do I use Table 1405.1.1.1.2 with my NFPA 268 result?

Find the maximum incident radiant heat flux the material tolerates without sustained flaming in the NFPA 268 test report, then find the matching tolerable flux value in Table 1405.1.1.1.2 — the table row gives the minimum allowable fire separation in feet per § 1405.1.1.1.2 .

Are there material exemptions from the NFPA 268 requirement?

Yes. § 1405.1.1.1 lists exceptions: wood/wood‑based products; combustible materials covered by an exterior weather covering (not vinyl) that meet Table 1404.2 thickness limits; and aluminum with minimum thickness 0.019 in (0.48 mm) are excepted from the NFPA 268 requirement .

If my building is greater than 40 ft tall, can I use combustible cladding?

The general limit in § 1405.1 is 40 ft above grade plane for combustible exterior wall coverings. Fire‑retardant‑treated wood has a separate allowance (up to 60 ft) if it meets § 2303.2; other special systems (MCM, EIFS, HPL, etc.) are governed by their sections and may have different provisions (§ 1405.1 and its exceptions) .

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California Building Code