CWUIC · California Wildland-Urban Interface Code
Surface-Burning, Heat‑Release & Combustibility Tests
This hub explains how the CWUIC uses surface‑burning, heat‑release and combustibility tests (ASTM and SFM methods) and their numeric acceptance criteria to qualify exterior materials and assemblies for wildfire exposure.
Last reviewed: July 6, 2026
Overview
This part of the California Wildland‑Urban Interface Code (CWUIC) sets the test methods and acceptance criteria used to evaluate surface‑burning behavior, heat‑release (HRR) and basic combustibility of exterior materials and assemblies exposed to wildfire hazard (decks, eaves, exterior wall coverings, roof components, vents, etc.). Key CWUIC provisions that implement these requirements include §503.2.4 (ignition‑resistant / surface‑burning criteria) and the decking requirements in §504.7.3.2 with its performance criteria in §504.7.3.3 and §504.7.3.4.
Why this matters: wildfire exposures introduce direct flame, burning brands and elevated radiant heat that can rapidly ignite or propagate fire through exterior elements. The CWUIC therefore ties material acceptance to specific test methods (for example, ASTM E2632 and ASTM E2726 for deck tests, ASTM E84/UL 723 for tunnel flame spread, and oxygen‑consumption calorimetry per ASTM E1354 for HRR) and numeric pass/fail thresholds so products used in WUI settings demonstrate measurable, repeatable performance. See the Deck test standards and conditions of acceptance in SFM Standard 12‑7A‑4 and the ASTM E2632/E2726 acceptance language in §504.7.3.3.
Where to look in the code: material qualification, labeling and approved‑agency requirements are in Chapter 5 (e.g., §503.3 and related subsections), while specific assembly tests and referenced standards (E2632, E2726, E84/UL 723, E1354, E136, etc.) appear in the CWUIC referenced‑standards and SFM test sections cited throughout Chapter 5 and Chapter 12 (deck and projection tests). These sections explain test setup, observation periods, and numeric acceptance criteria such as the peak HRR limits used for deck materials.
In this section
Code references
Grounded in the retrieved California Wildland-Urban Interface Code — click a citation to read the verbatim passage:
CWUIC § 12-7 High relevance — show source text
504.8
12-7A-3: Horizontal Projection Underside. A fire resistance test standard consisting of a 300 kW intensity direct flame exposure for a 10-minute duration
504.3, 504.7, 504.7.1
12-7A-4: Decking. A two-part test consisting of a heat release rate (Part A) deck assembly combustion test with an under deck exposure of 80 kW intensity direct flame for a 3-minute duration, and a (Part B) sustained deck assembly combustion test consisting of a deck upper surface burning ember exposure with a 12 mph wind for 40 minutes using a 2.2 lb (1kg) burning “Class A” size 12" × 12" × 2.25" (300 mm × 300 mm × 57 mm) roof test brand
504.7.3.2
12-7A-4A: Decking Alternate Method A. A heat release rate deck assembly combustion test with an under deck exposure of 80 kW intensity direct flame for a 3-minute duration
504.7.3.2
State Fire Marshal’s Guidelines for Fire Hydrant Markings Along State Highways and Freeways, May 1988
404.8
UL UL LLC, 333 Pfingsten Road, Northbrook, IL 60062-2096
9—2009: Fire Tests of Window Assemblies—with Revisions through March 2020
504.8
10B—2008: Fire Tests of Door Assemblies—with Revisions through May 2020
504.9
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REFERENCED STANDARDS
10C—2016: Positive Pressure Fire Tests of Door Assemblies—with Revisions through May 2021
504.9
94—2023: Tests for Flammability of Plastic Materials for Parts in Devices and Appliances
504.9.2
263—2011: Fire Tests of Building Construction and Materials—with Revisions through March 2022
501.3, 504.3, 504.3.1, 504.5, 504.7, 504.7.1
723—2018: Test for Surface Burning Characteristics of Building Materials
202, 501.4.1, 503.2.4, 504.7.3.2, 504.7.3.3
790— 2022 : Standard Test Methods for Fire Tests of Roof Coverings
504.2, 504.2.1.2, 504.11.6
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CALIFORNIA WILDLAND-URBAN INTERFACE CODE – MATRIX ADOPTION TABLE
APPENDIX A – GENERAL REQUIREMENTS
CWUIC § 504.7.3.3 High relevance — show source text
504.7.3.3 Performance requirements for Section 504.7.3.2, Item 1. Materials shall be tested in accordance with both ASTM E2632 and ASTM E2726 and comply with the conditions of acceptance in Sections 504.7.3.3.1 and 504.7.3.3.2. The material shall also be tested in accordance with ASTM E84 or UL 723 and comply with the performance requirements of Section 503.2.4.
504.7.3.3.1 Conditions of acceptance for ASTM E2632. The ASTM E2632 test shall be conducted on a minimum of three test specimens and meet the conditions of acceptance in Items 1 through 3. If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Peak heat release rate of less than or equal to 25 kW/ft2 (269 kW/m2).
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SPECIAL BUILDING CONSTRUCTION REGULATIONS
2. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period. 3. Absence of falling particles that are still burning when reaching the burner or floor.
504.7.3.3.2 Conditions of acceptance for ASTM E2726. The ASTM E2726 test shall be conducted, using a “Class A” size roof test brand, on a minimum of three test specimens and meet the conditions of acceptance in Items 1 and 2. If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period. 2. Absence of falling particles that are still burning when reaching the burner or floor.
504.7.3.4 Performance requirements for Section 504.7.3.2, Item 7. The ASTM E2632 test shall be conducted on a minimum of three test specimens and the peak heat release rate shall be less than or equal to 25 kW/ft [2] (269 kW/m [2] ). If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be run. All the additional tests shall meet the condi- tion of acceptance. If any one of the three tests does not meet the condition of acceptance, three additional tests shall be performed. All three additional tests must show a peak heat release rate shall be 25 kW/ft2 (269 kW/m2) or less.
504.8 Exterior glazing. Exterior windows, window walls and glazed doors, windows within exterior doors, and skylights shall be constructed of any of the following: 1. Multilayered glazed panels with at least one pane of tempered glass complying with Section 2406 of the California Building Code.
2. Glass block.
CWUIC § 7.1. High relevance — show source text
- Procedure.
7.1. Ignition. Ignite the burner, controlling for a constant 80 ± 4 kW output. 7.2. Flame exposure. Continue the exposure for a 3-minute period. Extinguish the burner.
7.3. Continued combustion. Continue observation for an additional 40 minutes or until all combustion has ceased.
- Observations. Note physical changes of the deck boards during the test, including structural failure of any deck board, location of flaming and glowing ignition, and loss of material (i.e., flaming drops of particles falling from the deck). It is desirable to capture the entire test with a video recorder to allow review of the details of performance.
12-7A-4.7.4 Report. The report shall include a description of the deck board material and the time of any degradation (effective net peak heat release rate, structural failure, flaming drops or particles falling from the deck) during the test.
- Calculated rate of heat release. The effective net peak heat release rate (HRR) shall be calculated as follows: 1.1. During the first 5 minutes of the test (the 3 minutes during which the ignition source burner is operating and the immediately following 2 minutes) the effective net peak HRR of the test assembly shall be reported as: effective net peak HRR = (peak heat release rate – 80 kW) / (deck surface area). 1.2. During the remaining test duration the effective net peak heat release rate of the test assembly shall be reported as: effective net peak HRR = (peak heat release rate) / (deck surface area).
12-7A-4.7.5 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.
- Effective net peak heat release rate of less than or equal to 25 kW/ft [2] (269 kW/m [2] ).
- Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period.
- Absence of falling particles that are still burning when reaching the burner or floor.
12-7A-4.8 PART B. Burning brand exposure.
12-7A-4.8.1 Equipment.
- Wind tunnel. The wind tunnel shall have the capability of providing 12 mph (5.4 m/s) airflow over the deck assembly.
- Anemometer. Device for measuring airflow across the deck.
- Burner. Gas-fueled burner for brand ignition.
12-7A-4.8.2 Test system preparation. See Figure 2. The ASTM E108 “A” brand roof test apparatus is to be used, with the following modifications:
- Deck support. The deck shall be supported horizontally with the center 60 inches (150 mm) from the front opening of the wind tunnel and the joists parallel to the airflow and resting on two transverse metal supports. The top surfaces of these supports, no more than 3 inches (75 mm) wide, are at the same height as the floor of the wind tunnel.
- Fragments. Burning fragments shall be free to fall to the floor of the room.
12-7A-4.8.3 Conduct of tests.
- Number of tests. Conduct the test on three replicate assemblies.
- **Moisture content.
CWUIC § 5.3. Medium relevance — show source text
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
5.3. Continued combustion. If penetration does not occur, continue observation for an additional 30 minutes or until all combustion has ceased.
Note: An infrared thermometer has been found to be useful to detect the increase of temperature on the back side of the eaves and as an aid to identify the areas of potential combustion. 6. Observations. Note the time, location and nature of flame penetration.
12-7A-3.9 Report. The report shall include a description of the eaves material, details of the construction of the eaves, moisture content of the framing and wood-based soffit elements as applicable, and point of flame penetration. Provide details on the time and reasons for early termination of the test.
12-7A-3.10 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance.
- Absence of flame penetration of the eaves or horizontal projection assembly at any time.
- Absence of structural failure of the eaves or horizontal projection subassembly at any time.
- Absence of sustained combustion of any kind at the conclusion of the 40-minute test.
FIGURE 1 — EAVES TEST ASSEMBLY
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
DECKING
SFM STANDARD 12-7A-4
12-7A-4.1 Application. The minimum design, construction and performance standards set forth herein for unloaded decks are those deemed necessary to establish conformance to the provisions of these regulations. Materials and assemblies that meet the performance criteria of this standard are acceptable for use as defined in California Building Standards Code.
12-7A-4.2 Scope. This standard evaluates the performance of decks (or other horizontal ancillary structures in close proximity to primary structures) when exposed to direct flames and brands. The under-deck flame exposure test is intended to determine the heat release rate (HRR) and degradation modes of deck or other horizontal boards when exposed to a burner flame simulating combustibles beneath a deck. The burning brand exposure test is intended to determine the degradation modes of deck or other horizontal boards when exposed to a burning brand on the upper surface.
12-7A-4.3 Referenced document.
ASTM D4444, Test Methods for Use and Calibration of Hand-Held Moisture Meters.
ASTM E108, Test Methods for Fire Tests of Roof Coverings.
California Building Code, Chapter 7A.
UL 790, Standard Test Methods for Fire Tests of Roof Coverings.
12-7A-4.4 Definitions.
- Deck boards. Horizontal members that constitute the exposed surface of the ancillary structure.
- Deck surface area. The test specimen area defined by the overall specimen length and width after assembly.
- Heat release rate. The net rate of energy release as measured by oxygen depletion calorimetry.
**12-7A-4.5 Test assembly.
CWUIC § 12-7 Medium relevance — show source text
12-7A-4.8.4 Report. The report shall include description of the deck board material, and the time of any degradation (accelerated combustion, board collapse, flaming drops or particles falling from the deck).
12-7A-4.8.5 Conditions of Acceptance. Should one of the three replicates fail to meet the Conditions of Acceptance, three additional tests may be run. All of the additional tests must meet the Conditions of Acceptance:
- Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period.
- Absence of falling particles that are still burning when reaching the burner or floor.
FIGURE 1 — DECK TEST ASSEMBLY (UNDER DECK-FLAME)
FIGURE 2 — DECK TEST ASSEMBLY (BURNING-BRAND)
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
DECKING ALTERNATE METHOD A
SFM STANDARD 12-7A-4A
12-7A-4A.1 Application. The minimum design, construction and performance standards set forth herein for unloaded decks are those deemed necessary to establish conformance to the provisions of these regulations. Materials and assemblies that meet the performance criteria of this standard are acceptable for use as defined in the California Building Standards Code.
12-7A-4A.2 Scope. This standard evaluates the performance of decks (or other horizontal ancillary structures in close proximity to primary structures) when exposed to direct flames and brands. The under-deck flame exposure test is intended to determine the heat release rate (HRR) and degradation modes of deck or other horizontal boards when exposed to a burner flame simulating combustibles beneath a deck. The burning brand exposure test is intended to determine the degradation modes of deck or other horizontal boards when exposed to a burning brand on the upper surface.
12-7A-4A.3 Referenced document.
- ASTM E108. Standard Test Methods for Fire Tests of Roof Coverings.
- California Building Code, Chapter 7A.
12-7A-4A.4 Definitions.
- Deck boards. Horizontal members that constitute the exposed surface of the ancillary structure.
- Heat release rate. The net rate of energy release as measured by oxygen depletion calorimetry.
12-7A-4A.5 Test assembly.
- Size. The overall size of the test deck shall be nominally 24 x 24 inches (610 x 610 mm) unless width variation of deck boards requires an increase in overall deck width (i.e., the direction of joists) in order to meet the overall dimensions. The length of individual deck boards shall be 24 inches (610 mm).
- Joists. The deck is supported by two nominal 2 x 6 Douglas-fir joists running perpendicular to the deck boards, and constructed with a 16-inch (406 mm) center-to-center spacing. A comparable species that may be more commonly used for structural framing of decks in a given region can be substituted for Douglas-fir.
- Deck board spacing and fastening. Edge-to-edge spacing and method of attachment shall conform to the manufacturer’s installation recommendations.
CWUIC § 914.3.1.2 Medium relevance — show source text
D3278—21: Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus
202
D3498—03(2011): Standard Specification for Adhesives for Field-Gluing Plywood to Lumber Framing for Floor Systems
701.6, 914.3.1.2, 3303.5
E84—21a: Standard Test Method for Surface Burning Characteristics of Building Materials
202, 803.1, 803.1.2, 803.3, 803.5.2, 803.10, 803.12, 803.13, 804.1.1, 804.1.2, 804.2.4, 3311.1
E108— 2020a : Standard Test Methods for Fire Tests of Roof Coverings
1207.9.5
E648—19ae1: Standard Test Method for Critical Radiant Flux of Floor-Covering Systems Using a Radiant Heat Energy Source
804.3.1, 804.3.2, 804.4
E681—09(2015): Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
202
E1354—22: Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter
304.3.2, 304.3.4, 318.1, 2310.5.3, 3304.1.3, 3311.1, 3603.4
E1529—16e1: Standard Test Method for Determining Effects of Large Hydrocarbon Pool Fires on Structural Members and Assemblies
5704.2.9.2.3
E1537—22: Test Method for Fire Testing of Upholstered Furniture
805.1.1.2, 805.2.1.2, 805.3.1.2, 805.4.1.2
E1590—2022: Test Method for Fire Testing of Mattresses
805.1.2.2, 805.2.2.2, 805.3.2.2.1, 805.4.2.2
E1966—15(2019): Standard Test Method for Fire-Resistant Joint Systems
202
E2072—14: Standard Specification for Photoluminescent (Phosphorescent) Safety Markings
1025.4
E2404—17: Standard Practice for Specimen Preparation and Mounting of Textile, Paper or Polymeric (Including Vinyl) and Wood Wall or Ceiling Coverings, Facing and Veneers to Assess Surface Burning Characteristics
803.5.1, 803.5.2, 803.12
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REFERENCED STANDARDS
E2573—19: Standard Practice for Specimen Preparation and Mounting of Site-Fabricated Stretch Systems to Assess Surface Burning Characteristics
803.10
E2579—21: Standard Practice for Specimen Preparation and Mounting of Wood Products to Assess Surface Burning Characteristics
803.13
E3082—20: Standard Test Methods for Determining the Effectiveness of Fire-Retardant Treatments for Natural Christmas Trees
806.1.4
CWUIC § 12-7 Medium relevance — show source text
DECKING
SFM STANDARD 12-7A-4
12-7A-4.1 Application. The minimum design, construction and performance standards set forth herein for unloaded decks are those deemed necessary to establish conformance to the provisions of these regulations. Materials and assemblies that meet the performance criteria of this standard are acceptable for use as defined in California Building Standards Code.
12-7A-4.2 Scope. This standard evaluates the performance of decks (or other horizontal ancillary structures in close proximity to primary structures) when exposed to direct flames and brands. The under-deck flame exposure test is intended to determine the heat release rate (HRR) and degradation modes of deck or other horizontal boards when exposed to a burner flame simulating combustibles beneath a deck. The burning brand exposure test is intended to determine the degradation modes of deck or other horizontal boards when exposed to a burning brand on the upper surface.
12-7A-4.3 Referenced document.
ASTM D4444, Test Methods for Use and Calibration of Hand-Held Moisture Meters.
ASTM E108, Test Methods for Fire Tests of Roof Coverings.
California Building Code, Chapter 7A.
UL 790, Standard Test Methods for Fire Tests of Roof Coverings.
12-7A-4.4 Definitions.
- Deck boards. Horizontal members that constitute the exposed surface of the ancillary structure.
- Deck surface area. The test specimen area defined by the overall specimen length and width after assembly.
- Heat release rate. The net rate of energy release as measured by oxygen depletion calorimetry.
12-7A-4.5 Test assembly.
- Size. The overall size of the test deck shall be nominally 24 x 24 inches (610 x 610 mm) unless width variation of deck boards requires an increase in overall deck width (i.e., the direction of joists) in order to meet the overall dimensions. The length of individual deck boards shall be 24 inches (610 mm).
- Joists. The deck is supported by two nominal 2 x 6 Douglas-fir joists running perpendicular to the deck boards, and constructed with a 16-inch (406 mm) center-to-center spacing. A comparable species that may be more commonly used for structural framing of decks in a given region can be substituted for Douglas-fir.
- Deck board spacing and fastening. Edge-to-edge spacing and method of attachment shall conform to the manufacturer’s installation recommendations. The front deck board shall be flush with the ends of the joists, and the rear deck board shall overhang the end of the joists by 1 inch (25 mm). 3.1. In the absence of recommended installation guidance, the edge-to-edge spacing shall be [3] / 16 inch (5 mm) with boards mechanically attached to the joists using deck screws. 3.2. If nominal 6-inch-wide (152 mm) deck boards are used, a total of 5 boards shall be used for each deck. Changing the board width could change the number of deck boards.
12-7A-4.6 Materials.
CWUIC § 602.4.2.4 Medium relevance — show source text
602.4.2.4 Roofs. The interior surfaces of roof assemblies shall be protected in accordance with Section 602.4.2.2 except, in nonoccupiable spaces, they shall be treated as a concealed space with no portion left unprotected. Roof coverings in accordance with Chapter 15 shall be permitted on the outside surface of the roof assembly.
602.4.2.5 Concealed spaces. Concealed spaces shall not contain combustibles other than electrical, mechanical, fire protection, or plumbing materials and equipment permitted in plenums in accordance with the California Mechanical Code, and shall comply with all applicable provisions of Section 718. Combustible construction forming concealed spaces shall be protected in accordance with Section 602.4.1.2.
602.4.2.6 Shafts. Shafts shall be permitted in accordance with Sections 713 and 718. Both the shaft side and room side of mass timber elements shall be protected in accordance with Section 602.4.1.2.
602.4.3 Type IV-C. Building elements in Type IV-C construction shall be protected in accordance with Sections 602.4.3.1 through 602.4.3.6. The required fire-resistance rating of building elements shall be determined in accordance with Section 703.2.
602.4.3.1 Exterior protection. The exterior side of walls of combustible construction shall be protected with noncombustible protection with a minimum assigned time of 40 minutes, as determined in Table 722.7.1(1). Components of the exterior wall covering shall be of noncombustible material except water-resistive barriers having a peak heat release rate of less than 150 kW/m [2], a total heat release of less than 20 MJ/m [2] and an effective heat of combustion of less than 18 MJ/kg as determined in accordance with ASTM E1354 and having a flame spread index of 25 or less and a smoke-developed index of 450 or less as determined in accordance with ASTM E84 or UL 723. The ASTM E1354 test shall be conducted on specimens at the thickness intended for use, in the horizontal orientation and at an incident radiant heat flux of 50 kW/m [2] .
602.4.3.2 Interior protection. Mass timber elements are permitted to be unprotected.
602.4.3.3 Floors. Floor finishes in accordance with Section 804 shall be permitted on top of the floor construction.
602.4.3.4 Roof coverings. Roof coverings in accordance with Chapter 15 shall be permitted on the outside surface of the roof assembly.
602.4.3.5 Concealed spaces. Concealed spaces shall not contain combustibles other than electrical, mechanical, fire protection, or plumbing materials and equipment permitted in plenums in accordance with the California Mechanical Code, and shall comply with all applicable provisions of Section 718. Combustible construction forming concealed spaces shall be protected with noncombustible protection with a minimum assigned time of 40 minutes, as specified in Table 722.7.1(1).
602.4.3.6 Shafts. Shafts shall be permitted in accordance with Sections 713 and 718. Shafts and elevator hoistway and interior exit stairway enclosures shall be protected with noncombustible protection with a minimum assigned time of 40 minutes, as specified in Table 722.7.1(1), on both the inside of the shaft and the outside of the shaft.
**602.4.4 Type IV-HT.
CWUIC § 2.1 Medium relevance — show source text
agency BSC BSC-
CGSFM 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-
CGSFM 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 belowX 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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14-2 2025 CALIFORNIA BUILDING CODE
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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.
CWUIC § 504.7.3.2 Medium relevance — show source text
504.7.3.2 Decking surfaces. The walking surface material of decks, porches, balconies and stairs shall be constructed with any of the following materials: 1. Material that complies with the performance requirements of Section 504.7.3.3 when tested in accordance with ASTM E2632 and ASTM E2726.
2. Ignition-resistant building material that complies with the performance requirements of Section 503.2.4. 3. Material that complies with the performance requirements of both SFM Standard 12-7A-4 and Section 503.2.4. 4. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code.
5. Noncombustible material.
6. Any material that complies with the performance requirements of SFM Standard 12-7A-4A and any attached exterior wall covering that is noncombustible or ignition-resistant building materials. Exception: Wall material shall be permitted to be of any material that otherwise complies with this chapter when the decking surface material complies with the performance requirements of ASTM E84 or UL 723 with a Class B flame spread index.
7. Any material that complies with the performance requirements of Section 504.7.3.4 when tested in accordance with ASTM E2632 and any attached exterior wall covering that is noncombustible or ignition-resistant building materials. Exception: Wall material shall be permitted to be of any material that otherwise complies with this chapter when the decking surface material complies with the performance requirements of ASTM E84 or UL 723 with a Class B flame spread index.
504.7.3.3 Performance requirements for Section 504.7.3.2, Item 1. Materials shall be tested in accordance with both ASTM E2632 and ASTM E2726 and comply with the conditions of acceptance in Sections 504.7.3.3.1 and 504.7.3.3.2. The material shall also be tested in accordance with ASTM E84 or UL 723 and comply with the performance requirements of Section 503.2.4.
504.7.3.3.1 Conditions of acceptance for ASTM E2632. The ASTM E2632 test shall be conducted on a minimum of three test specimens and meet the conditions of acceptance in Items 1 through 3. If any one of the three tests does not meet the conditions of acceptance, three additional tests shall be performed. All three additional tests must meet the conditions of acceptance. 1. Peak heat release rate of less than or equal to 25 kW/ft2 (269 kW/m2).
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SPECIAL BUILDING CONSTRUCTION REGULATIONS
2. Absence of sustained flaming or glowing combustion of any kind at the conclusion of the 40-minute observation period. 3. Absence of falling particles that are still burning when reaching the burner or floor.
CWUIC § 501.3 Medium relevance — show source text
501.3, 504.3, 504.3.1, 504.5, 504.7, 504.7.1
E136— 2024a : Standard Test Method for Assessing Combustibility of Materials Using a Vertical Tube Furnace at 750 Degrees C
501.4.1
E1354— 2023 : Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter
503.2.4.3.2, 503.2.4.3.3
E2632—2020: Standard Test Method for Evaluating the Under-Deck Fire Test Response of Deck Materials
504.7.3.2, 504.7.3.3, 504.7.3.3.1, 504.7.3.4
E2652—2022: Standard Test Method for Assessing Combustibility of Materials Using a Tube Furnace with a Cone-shaped Airflow Stabilizer, at 750°C
501.4.1
E2707—2022: Standard Test Method for Determining Fire Penetration of Exterior Wall Assemblies Using a Direct Flame Impingement Exposure
504.5, 504.9, 504.9.3
E2726/E2726M—2012a(2017): Standard Test Method for Evaluating the Fire Test Response of Deck Structures to Burning Brands
504.7.3.2, 504.7.3.3, 504.7.3.3.2
E2768—11(2018): Standard Test Method for Extended Duration Surface Burning Characteristics of Building Materials (30 min Tunnel Test)
503.2.4
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REFERENCED STANDARDS
E2886/E2886M—20: Standard Test Method for Evaluating the Ability of Exterior Vents to Resist the Entry of Embers and Direct Flame Impingement
504.10.1
E2957—2017 : Standard Test Method for Resistance to Wildfire Penetration of Eaves, Soffits and Other Projections
504.3, 504.7, 504.7.1, 504.7.2
G155—2021: Standard Practice for Operating Xenon Arc Lamp Apparatus for Exposure of Materials
504.9.2
ICC International Code Council, Inc., 200 Massachusetts Avenue, NW, Suite 250, Washington, DC 20001
CBC—2025: California Building Code
CWUIC § 1025.2.6.1 Medium relevance — show source text
170— 24 : Standard for Fire Safety and Emergency Symbols
1025.2.6.1
211— 24 : Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances
2112.5
221—24: Standard for High Challenge Fire Walls, Fire Walls and Fire Barrier Walls 706.2, Table 716.1(2)
252—22: Standard Methods of Fire Tests of Door Assemblies
Table 716.1(1), 716.1.1, 716.1.2.2.1, 716.2.1.1, 716.2.1.2, 716.2.2.1, 716.2.2.2, 716.2.2.3.1, 716.2.5.1.1
253—23: Standard Method of Test for Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat Energy Source
406.2.4, 424.2, 804.2, 804.3
257—22: Standard on Fire Test for Window and Glass Block Assemblies
Table 716.1(1), 716.1.1, 716.1.2.2.2, 716.3.1.1, 716.3.1.2, 716.3.2.1.3, 716.3.4
259—23: Standard Test Method for Potential Heat of Building Materials
2603.4.1.10, 2603.5.3
265—23: Standard Methods of Fire Tests for Evaluating Room Fire Growth Contribution of Textile or Expanded Vinyl Wall Coverings on Full Height Panels and Walls
803.5.1, 803.5.1.1
268—22: Standard Test Method for Determining Ignitability of Exterior Wall Assemblies Using a Radiant Heat Energy Source
1405.1.1.1, 1405.1.1.1.1, 1405.1.1.1.2, 2603.5.7
275—22: Standard Method of Fire Tests for the Evaluation of Thermal Barriers
508.4.4.1, 509.4.1.1, 1406.10.2, 1408.10.2, 2603.4
276—23: Standard Method of Fire Test for Determining the Heat Release Rate of Roofing Assemblies with Combustible Above- Deck Roofing Components
1508.1, 2603.3, 2603.4.1.5
285—23: Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components
718.2.6, 1402.6, 1406.10.3, 1408.10.4, 1511.6.2, 2603.5.5
286— 24 : Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth
402.6.4.4, 424.2, 803.1.1, 803.1.1.1, 803.11, 803.12, 803.13, 1406.10.2, 1408.10.3, 2603.7, 2603.9, 2604.2.4, 2614.4, 3105.3
Frequently asked questions
Which laboratory tests does the CWUIC use to qualify decking materials?
Decking is evaluated by an under‑deck heat‑release (ASTM E2632) and a burning‑brand exposure (ASTM E2726) with acceptance criteria spelled out at §504.7.3.3; ASTM E84/UL 723 (tunnel) testing also appears as an acceptance path in some cases. See the deck test standard SFM 12‑7A‑4 and §504.7.3.2–§504.7.3.4 for details.
What heat‑release limits should I watch for in CWUIC?
A commonly applied limit for deck assemblies and some decking tests is a peak heat release rate ≤ 25 kW/ft² (269 kW/m²) as specified in §504.7.3.3.1; other applications (for example, water‑resistive barriers and some wall components) reference ASTM E1354 thresholds (e.g., specified peak and total HRR limits in the building code cross‑references).
How does the code ensure long‑term (weathered) performance?
For particular materials (wood‑plastic composites, plastic lumber, fire‑retardant‑treated wood), the CWUIC requires weathering protocols and retesting (including ASTM E1354 HRR retesting) so that peak HRR does not increase beyond permitted limits after accelerated weathering. See the weathering and retest procedures in §503.2.4.3.
More in California Wildland-Urban Interface Code
- Administration and Definitions
- Board of Appeals, Administration & Enforcement (permits, code official duties, appeals process)
- Wildland‑Urban Interface Area Designation & Mapping
- Fire Service Access & Water Supply (fire apparatus roads, driveways, hydrants, draft sites, standby power)
- Wildland‑Urban Interface Area Requirements (access, water, premises identification, key boxes)
- Referenced Standards & Test Methods
- Special Building Construction Regulations (ignition‑resistant construction, roof/vent/assembly requirements)
- Appendices and Model Ordinances (vegetation plans, severity‑zone adoption, home‑hardening guidance)
- Fire Protection Requirements (fire protection plans, systems, safety element provisions)
- Referenced California Documents & Matrix (CCR/Title 14 & 19 cross‑references, statutory references)
- Vegetation Management & Defensible Space (vegetation plans, maintenance, fire‑smart characteristics)
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