CWUIC · California Wildland-Urban Interface Code
How does CWUIC reference tests for wildfire penetration of eaves/soffits?
If you plan boxed‑in eaves/soffits in a Wildland‑Urban Interface area, the CWUIC lets you use assemblies that pass the wildfire‑penetration tests (ASTM E2957 or SFM 12‑7A‑3) instead of only prescriptive materials. The tests use 4×2 ft specimens exposed to a 300±15 kW burner, require three passing replicates (or three additional passing tests if one fails), and require no flame penetration, no structural failure and no sustained combustion at the end of the ~40‑minute test period.
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
The California Wildland‑Urban Interface Code requires that the exposed underside of enclosed eaves and soffits be protected by listed materials or by assemblies that meet performance tests. The code accepts boxed‑in eave/soffit assemblies that pass the wildfire‑penetration test ASTM E2957 or the State Fire Marshal SFM Standard 12‑7A‑3 as alternatives to prescriptive materials (§ 504.3, § 504.7, § 504.7.1) .
The single most important rule: boxed‑in eaves/soffits may be accepted only if the assembly meets the test performance criteria in ASTM E2957 or SFM 12‑7A‑3 — otherwise you must use one of the prescriptive protection options listed in § 504.3 or § 504.7.
Requirements in detail
Which code sections control this requirement
- § 504.3 — protection of enclosed eaves: lists prescriptive options and allows boxed‑in soffit assemblies that meet test criteria in ASTM E2957 or SFM 12‑7A‑3 .
- § 504.7 — general requirements for projections and allowable tested alternatives for undersides of projections (references test acceptance criteria) .
- § 504.7.1 — underside of projections options, including materials and the two test standards (ASTM E2957 and SFM 12‑7A‑3) as alternatives .
- The code specifically references ASTM E2957 and SFM Standard 12‑7A‑3 as the test procedures to evaluate wildfire penetration resistance .
What the referenced tests actually require (decision‑relevant dimensions and values)
The table below summarizes the key test inputs and acceptance thresholds you will use to determine whether a boxed‑in eave/soffit assembly complies.
| Decision item | Value / threshold | Where in the test / code | Code Reference |
|---|---|---|---|
| Test standard(s) accepted | ASTM E2957 (2017) or SFM 12‑7A‑3 | CWUIC accepts these standards for boxed‑in eaves/soffits | § 504.3, § 504.7, § 504.7.1 |
| Specimen size (eaves test) | 4 ft × 2 ft (1.2 m × 0.6 m) | Eave test specimen dimension per SFM 12‑7A‑3 | SFM 12‑7A‑3 (test setup) |
| Burner heat output | 300 ± 15 kW | Burner net heat output for eaves test (controlled) | SFM 12‑7A‑3 (conduct) |
| Burner positioning | Top of assembly 84 in (2.1 m) above burner; centered; 0.75 in (20 mm) from wall; floor to top of burner = 12 in (300 mm) | Test fixture geometry and burner placement | SFM 12‑7A‑3 (conduct) |
| Number of replicates | 3 specimens minimum; if one fails, run 3 additional tests and all must meet acceptance | Replicate testing and re‑test requirement | § 504.7.2 (conditions for ASTM E2957) and SFM 12‑7A‑3 |
| Exposure duration | Flame exposure until penetration occurs or 10 minutes; if no penetration, continue observation up to 30 additional minutes (total observation period ~40 minutes) | SFM 12‑7A‑3 procedure and conditions of acceptance | |
| Moisture conditioning | Lumber 8–12% moisture (oven‑dry basis); sheathing ≤ 8%; condition to constant weight or 30 days at 73 ±4°F and 50 ±5% RH | Materials conditioning requirements in test prep | SFM 12‑7A‑3 (materials & prep) |
| Sealing around specimen | Edges and ends sealed with ceramic wool or comparable material to prevent edge leakage | Test fixture preparation instruction | SFM 12‑7A‑3 (test prep) |
| Conditions of Acceptance (pass) | 1) Absence of flame penetration at any time; 2) No structural failure of subassembly; 3) No sustained combustion at conclusion of the 40‑minute test | Acceptance criteria for ASTM E2957 and SFM 12‑7A‑3 | § 504.7.2 and SFM 12‑7A‑3 |
(Each numeric item above is taken from the SFM test procedure and the CWUIC references to ASTM E2957 and SFM 12‑7A‑3.)
How ASTM E2957 and SFM 12‑7A‑3 are used in the Code
- CWUIC references ASTM E2957 as the standard test method for resistance to wildfire penetration of eaves/soffits and allows assemblies that meet its conditions of acceptance as an alternative protection method in § 504.3 and § 504.7 .
- SFM 12‑7A‑3 provides the detailed eaves test fixture, burner set‑up, specimen preparation, test conduct, and reporting requirements that the state uses; its acceptance criteria mirror the CWUIC pass/fail approach (3 specimens, reruns if one fails, 40‑minute observation) .
Exceptions & special cases
- Structural columns/beams: the code excepts structural columns and beams from the protection requirements in § 504.7.1 when constructed from sawn lumber or glulam with minimum nominal dimension 4 inches (102 mm); such members need not be separately protected per that exception (but see full text of § 504.7.1 for splining/fastening requirements) .
- Prescriptive options still allowed: If you choose a prescriptive material (noncombustible, ignition‑resistant, 1‑hour rated, 2‑inch nominal lumber, or specified FRTW), you do not need to perform the test — tests are an alternative path, not the only path (§ 504.3, § 504.7.1) .
- Test reruns: If one of the initial three specimens fails, you must test three additional specimens and all three additional tests must pass for the assembly to be accepted (no averaging or partial credit) — this is required by both ASTM E2957 acceptance rules as adopted and SFM practice in the code references .
Common mistakes
- Treating the 10‑minute flame exposure as the full acceptance period. The eaves test exposures run until penetration or for 10 minutes, but acceptance looks at sustained combustion after a total observation period (≈40 minutes) — don’t assume survival of the 10‑minute exposure alone equals pass .
- Forgetting specimen conditioning. Not conditioning wood/sheathing to the specified moisture content (lumber 8–12%, sheathing ≤8%) invalidates the test conditions and may change results .
- Failing to seal specimen edges. The test requires sealing edges/ends with ceramic wool (or comparable) to prevent edge leakage — unsealed edges create test artifacts and can cause invalid or noncomparable results .
- Running fewer than three replicates or assuming a single passed specimen suffices. CWUIC requires three replicates and, if one fails, three more passing tests are required .
- Confusing prescriptive material lists with test acceptance: a product that passes ASTM E2957 meets the “boxed‑in” alternative only if the test report documents the assembly as built and meets the code’s acceptance criteria — the manufacturer’s generic product listing alone is not enough without the test assembly and report matching the installed condition .
Worked example
Scenario: You plan a boxed‑in eave assembly with a cement‑fiber soffit panel over typical wood rafters and want to use the tested‑assembly path rather than prescriptive materials.
- Test plan: Prepare three 4 ft × 2 ft specimens of the actual assembly (same framing, soffit panel, fasteners, seams) and condition the lumber to 8–12% moisture and sheathing to ≤8% per SFM 12‑7A‑3 .
- Test setup: Install each specimen in the SFM test module with the horizontal surface 84 in (2.1 m) above the burner; set the burner to 300 ± 15 kW and position it centered and 0.75 in (20 mm) from the wall; verify output per the standard .
- Conduct test: Ignite and expose each specimen until flame penetration occurs or for 10 minutes; if penetration does not occur, observe the specimen for an additional 30 minutes (total ~40 minutes) for sustained combustion as required by the acceptance criteria .
- Evaluate results: If none of the three specimens shows flame penetration, structural failure, or sustained combustion at the conclusion of the test period, the assembly meets the CWUIC acceptance criteria and can be used in lieu of the prescriptive options in § 504.3 and § 504.7.1 .
- If one of the three fails, perform three additional tests; all three additional tests must pass for final acceptance per § 504.7.2 .
Related provisions
- § 504.3 — Protection of enclosed eaves (lists prescriptive options and allows tested assemblies)
- § 504.7 — Projections (material and tested‑assembly alternatives)
- § 504.7.1 — Underside of projections (options and exceptions)
- § 504.7.2 — Conditions of acceptance for ASTM E2957 (three specimens, re‑test requirement, acceptance criteria)
- ASTM E2957 — Standard test method referenced by the CWUIC for resistance to wildfire penetration of eaves/soffits (adopted and cross‑referenced)
- SFM Standard 12‑7A‑3 — Detailed state test procedure for horizontal projection (eaves/soffit) assembly testing, burner setup, specimen prep, conduct, reporting and acceptance criteria
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
- Test Fixture. The test fixture shall be as described in SFM 12-7A-1, with the exception that the top soffit projection of the wall assembly fixture is modified to facilitate installation and removal of eave assemblies. Gypsum board (or equivalent) is used to create a noncombustible wall surface in the 4 x 8 ft. opening in the wall test fixture.
- Eaves assembly. Fit the eave assembly into the test module so that the horizontal surface of the assembly is 84 inches (2.1 m) from the top of the burner.
- Moisture content. Measure the moisture content of the wooden members of the assembly using a moisture meter (ASTM D4444), and for sheathing products, by methods outlined in ASTM D4442.
- Sealing. Seal the edges and ends with ceramic wool or comparable material to prevent flame penetration in these locations of the eave assembly.
12-7A-3.8 Conduct of Tests.
Airflow. The wall test shall be conducted under conditions of ambient airflow.
Number of tests. Conduct the tests on three replicate eaves assemblies.
Burner output verification. Without the eaves assembly in place, adjust the burner for 300 ± 15 kW output. Extinguish the burner.
Burner positioning. Center the burner with respect to the width of the eaves wall assembly and 0.75 inch (20 mm) from the wall. The distance from the floor to the top of the burner shall be 12 inches (300 mm).
Procedure.
5.1. Ignition. Ignite the burner, controlling for a constant 300 ± 15 kW output. 5.2. Flame exposure. Continue the exposure until flame penetration of the eaves occurs or for a 10-minute period.
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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
CWUIC § 5.3. High 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 § 504.9 High relevance — show source text
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
2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 7-3
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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
1.1.7.3.1, 1.11.2.1.2, 1.11.3.4, 1.11.6 – 1.11.10, 101.3.1, 102.8, 105.1, 105.3, 106.3, 202, 404.10.3, 501.1, 501.3, 503.1, 503.2.2, 503.2.3, 504.2.1.2, 504.3, 504.3.1, 504.5, 504.5.2, 504.6, 504.7, 504.7.3.2, 504.8, 504.11, 504.11.1
CEBC—2025: California Existing Building Code
1.11.3.4, 102.8, 201.3
CFC—2025: California Fire Code
1.11.3.4, 1.11.9, 1.11.10, 102.8, 105.1, 201.3, 202, 402.1.1, 402.1.2, 402.2.1, 402.2.2, 403.2.4, 404.2, 404.4, 404.5, 404.10.3, 606.1, 606.2
CRC—2025: California Residential Code
1.1.7.3.1, 102.8
NFPA National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169-7471
CWUIC § 7.3.2 High relevance — show source text
E2925—19a: Standard Specification for Manufactured Polymeric Drainage and Ventilation Materials Used to Provide a Rainscreen Function
R703.7.3.2
E2957—2015: Standard Test Method for Resistance to Wildfire Penetration of Eaves, Soffits and Other Projections
R337.7.5, R337.7.6, R337.7.8, R337.7.10
*ASTM E2957, Amended Sections as follows:
Add new Section 12.5 as follows:
12.5 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. 1. Absence of flame penetration of the eaves or horizontal projection assembly at any time. 2. Absence of structural failure of the eaves or horizontal projection subassembly at any time. 3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.
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REFERENCED STANDARDS
F844—19: Standard Specification for Washers, Steel, Plain (Flat), Unhardened for General Use
Table R507.2.3
F1554—20: Specification for Anchor Bolts, Steel, 36, 55 and 105-ksi Yield Strength
R608.5.2.2
F1667—21a: Specification for Driven Fasteners: Nails, Spikes, and Staples Table R507.2.3, Table R602.3(1), R703.3.3, R703.6.3, Table R703.15.1, Table R703.15.2, R905.2.5
F2090—21: Specification for Window Fall Prevention Devices with Emergency Escape (Egress) Release Mechanisms
R319.1.1, R321.2.1, R321.2.2
F2374: Standard Practice for Design, Manufacture, Operation, and Maintenance of Inflatable Amusement Devices
AWC American Wood Council 222 Catoctin Circle SE, Suite 201 Leesburg, VA 20175
ANSI/AWC NDS—2024: National Design Specification (NDS) for Wood Construction—with 2018 Supplement R404.2.2, R502.2, Table R503.1, R507.2.1, R602.3, R608.9.2, R608.9.3, Table R703.15.1, Table R703.15.2, R802.2
ANSI/AWC PWF—2021: Permanent Wood Foundation Design Specification
R304.3.2, R401.1, R404.2.3
ANSI/AWC WFCM—2024: Wood Frame Construction Manual for One- and Two-Family Dwellings R301.1.1, R301.2.1.1, R602.10.8.2, Figure R608.9(9), R608.9.2, R608.9.3, R608.10
AWC STJR—2024: Span Tables for Joists and Rafters
R502.3, R802.4.1, R802.5.1
CWUIC § 12-7 High relevance — show source text
Note the time elapsed and location of penetration if it occurs. 4. Report. Report a description of the window unit, including the types of frames, cladding and panes being tested and details of the installation. Record when and how the glass breaks or flame-through occurs in the framing materials or sash, and/or
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
if the framing material deforms or otherwise suffers a loss of integrity such that the glass cannot be held in place, and a record of the time at which any of these events occur.
12-7A-2.8 Conditions of Acceptance.
- Duration of direct flame exposure. To pass this test standard, the window and window assembly shall withstand 8 minutes of direct flame exposure with the absence of flame penetration through the window frame or pane, or structural failure of the window frame or pane.
- Flame penetration or structural failure. Flame penetration or structural failure of the flame or pane anytime during the test constitutes failure of this test standard.
FIGURE 1 — SCHEMATIC OF THE WALL ASSEMBLY Test Module used for evaluating the fire performance of a window.
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
HORIZONTAL PROJECTION UNDERSIDE
SFM STANDARD 12-7A-3
12-7A-3.1 Application. The minimum design, construction and performance standards set forth herein for the exposed underside of horizontal projections such as the horizontal soffits of roof eaves, floor projections and exposed underfloor areas 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-3.2 Scope. This standard evaluates the fire-resistive performance of horizontal projection assemblies including the horizontal soffits of roof eaves, floor projections and exposed underfloor areas when subjected to direct flame exposure to the underside of a horizontal projection.
12-7A-3.3 Referenced documents.
ASTM D4442, Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials.
ASTM D4444, Test Methods for Use and Calibration of Hand-Held Moisture Meters.
California Building Code, Chapter 7A.
12-7A-3.4 Definitions.
- Eaves. A projecting edge of a roof that extends beyond the supporting wall as in CBC 702A “Roof Eave” or similar horizontal projection assembly.
- Soffit. The enclosed underside of any exterior overhanging section of a roof eave or similar horizontal projection assembly (see CBC 702A “Roof Eave Soffit”).
12-7A-3.5 Equipment.
- Burner. A 12 by 12-inch (300 by 300 mm) diffusion burner shall be used. Natural gas, methane or propane shall be supplied to the burner through a metered control system.
CWUIC § 501.3 High 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
2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 7-3
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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 § 1.3.3.6.1 High relevance — show source text
E2634—2018: Standard Specification for Flat Wall Insulating Concrete Form (ICF) Systems
R404.1.3.3.6.1, R608.4.4
E2634—2018: Standard Specification for Flat Wall Insulating Concrete Form (ICF) Systems
R404.1.3.3.6.1, R608.4.4
E2707—2015: tandard Test Method for Determining Fire Penetration of Exterior Wall Assemblies Using a Direct Flame Impingement Exposure
R337.7.3, R337.7.3.1, R337.8.3
E2726/E2726M—2012a: tandard Test Method for Evaluating the Fire-Test-Response of Deck Structures to Burning Brands
R337.9.3, R337.9.4, R337.9.4.2
E2886/E2886M—2014: Standard Test Method for Evaluating the Ability of Exterior Vents to Resist the Entry of Embers and Direct Flame Impingent
R337.6.2, R337.6.3
*ASTM E2886, Amended Sections as follows:
Revise Sections 10.1.8.3, 10.1.8.4 and 10.1.8.5 as follows: 10.1.8.3 Report the temperatures of the unexposed temperatures on the unexposed side of the vent during the entire optional Insula- tion Test of the Flame Intrusion.
10.1.8.4 The maximum temperature reached during the test by any one of the unexposed surface thermocouples during the entire optional Insulation Test of the Flame Intrusion Test. 10.1.8.5 The maximum average temperature reached during the test by all of the unexposed surface thermocouples during the entire optional Insulation Test of the Flame Intrusion Test.
E2925—19a: Standard Specification for Manufactured Polymeric Drainage and Ventilation Materials Used to Provide a Rainscreen Function
R703.7.3.2
E2957—2015: Standard Test Method for Resistance to Wildfire Penetration of Eaves, Soffits and Other Projections
R337.7.5, R337.7.6, R337.7.8, R337.7.10
*ASTM E2957, Amended Sections as follows:
Add new Section 12.5 as follows:
12.5 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. 1. Absence of flame penetration of the eaves or horizontal projection assembly at any time. 2. Absence of structural failure of the eaves or horizontal projection subassembly at any time. 3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.
2025 CALIFORNIA RESIDENTIAL CODE 44-13
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
REFERENCED STANDARDS
F844—19: Standard Specification for Washers, Steel, Plain (Flat), Unhardened for General Use
Table R507.2.3
CWUIC § 504.7.1 High relevance — show source text
Exception: Structural columns and beams are not required to be protected in accordance with Section 504.7.1 when constructed with sawn lumber or glue-laminated wood with the smallest minimum nominal dimension of 4 inches (102 mm). Sawn or glue- laminated planks shall be splined, tongue-and-groove, or set close together and well spiked.
504.7.2 Conditions of acceptance for ASTM E2957. The ASTM E2957 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. Absence of flame penetration of the eaves or horizontal projection assembly at any time. 2. Absence of structural failure of the eaves or horizontal projection subassembly at any time. 3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.
504.7.3 Decks. The walking surface material of decks, porches, balconies and stairs shall comply with the requirements of Sections 504.7.3.1 through 504.7.3.4.
504.7.3.1 Flashing. A minimum of a 6-inch (150 mm) metal flashing, applied vertically on the exterior of the wall, shall be installed at all deck-to-wall intersections.
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.
CWUIC § 12-7 High relevance — show source text
SPECIAL BUILDING CONSTRUCTION REGULATIONS
8. The underside of a floor projection assembly that meets the performance criteria in accordance with the test procedures set forth in SFM Standard 12-7A-3.
504.7.1 Underside of projections. The underside of projections shall be enclosed to grade in accordance with the requirements of this chapter or the underside of the exposed underfloor shall be protected by one or more of the following:
1. Noncombustible material.
2. Ignition-resistant building material shall be labeled for exterior use and shall meet the requirements of Section 503.2. 3. Fire-retardant-treated wood shall be labeled for exterior use and shall meet the requirements of Section 2303.2. 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 an exterior covering on the underside of the floor projection. 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 floor, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual. 7. The underside of a floor assembly that meets the performance criteria in Section 504.7.2 when tested in accordance with the test procedures set forth in ASTM E2957. 8. The underside of a floor assembly that meets the performance criteria in accordance with the test procedures set forth in SFM Standard 12-7A-3.
Exception: Structural columns and beams are not required to be protected in accordance with Section 504.7.1 when constructed with sawn lumber or glue-laminated wood with the smallest minimum nominal dimension of 4 inches (102 mm). Sawn or glue- laminated planks shall be splined, tongue-and-groove, or set close together and well spiked.
504.7.2 Conditions of acceptance for ASTM E2957. The ASTM E2957 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. Absence of flame penetration of the eaves or horizontal projection assembly at any time. 2. Absence of structural failure of the eaves or horizontal projection subassembly at any time. 3. Absence of sustained combustion of any kind at the conclusion of the 40-minute test.
504.7.3 Decks. The walking surface material of decks, porches, balconies and stairs shall comply with the requirements of Sections 504.7.3.1 through 504.7.3.4.
504.7.3.1 Flashing. A minimum of a 6-inch (150 mm) metal flashing, applied vertically on the exterior of the wall, shall be installed at all deck-to-wall intersections.
CWUIC § 2.2. High relevance — show source text
2.2. Gypsum board for mounting around the window once it is installed; 2.3. Pieces of gypsum cut into narrow strips for use as trim around the window; 2.4. Caulk to be used as per the window manufacturer's instructions. 3. Wall assembly. A noncombustible wall shall be used with a manufacturer or code-specified opening for the particular window. Install window in framed rough opening following manufacturer guidelines. Apply manufacturer-recommended caulk to nailing flange prior to installation. Use narrow strips of gypsum board as trim around window, covering the nail flange of the window. Any type of framing material may be tested. 3.1. Fit the window test assembly into the rear wall of the Wall Assembly Test Module, sealing all edges, including the soffit-to-wall joint. Ceramic wool or comparable material shall be used for sealing.
12-7A-2.7 Conduct of tests.
Burner output verification. Without the window in place, set the burner for 150 kW output. Conduct a verification run of 3 minutes to assure the heat release rate, and then turn off the burner.
Test. Place the burner against the wall assembly at the center. Ignite the burner at the 150 kW output and control during the test for constant and uniform output. Optional radiometers can be placed behind the Wall Assembly Test Module to measure heat flux through the window glass.
Duration and observations. The test shall be continued until flame-through occurs at the window. Flame-through can occur at the glass (glazing) and/or in the frame. At this point, the burner shall be extinguished and the assembly monitored for sustained combustion. Note the time elapsed and location of penetration if it occurs.
Report. Report a description of the window unit, including the types of frames, cladding and panes being tested and details of the installation. Record when and how the glass breaks or flame-through occurs in the framing materials or sash, and/or
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
if the framing material deforms or otherwise suffers a loss of integrity such that the glass cannot be held in place, and a record of the time at which any of these events occur.
12-7A-2.8 Conditions of Acceptance.
- Duration of direct flame exposure. To pass this test standard, the window and window assembly shall withstand 8 minutes of direct flame exposure with the absence of flame penetration through the window frame or pane, or structural failure of the window frame or pane.
- Flame penetration or structural failure. Flame penetration or structural failure of the flame or pane anytime during the test constitutes failure of this test standard.
FIGURE 1 — SCHEMATIC OF THE WALL ASSEMBLY Test Module used for evaluating the fire performance of a window.
42 2025 CALIFORNIA REFERENCED STANDARDS CODE
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MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
HORIZONTAL PROJECTION UNDERSIDE
SFM STANDARD 12-7A-3
CWUIC § 12-7 High relevance — show source text
Natural gas, methane or propane shall be supplied to the burner through a metered control system. The gas supply to the burner shall produce a net heat output of 300 ± 15 kW throughout the flame exposure. Burner output can be determined from HRR or calculated from the gas flow rate, temperature and pressure. 2. Infrared temperature analyzer (optional). Intended for monitoring the temperature change of the inside of the eaves. 3. Moisture content. Prior to testing, all materials (lumber and soffit material) shall be conditioned to a constant weight or for a minimum of 30 days at 73 ± 4°F (23 ± 2°C) and 50 ± 5% relative humidity, whichever occurs first. Constant weight shall be defined as occurring when the change in test material weight is less than or equal to 2 percent in a 24-hour period. Lumber moisture content shall be between 8 and 12 percent (oven-dry basis) and sheathing shall not exceed 8 percent (oven-dry basis).
12-7A-3.6 Materials.
Framing. The materials used shall be representative of the grades that would be typical of eave construction and installed in the eave’s subassembly as per accepted construction practices.
Soffit. Material selected for the test.
12-7A-3.7 Test system preparation (Figure 1).
- Eaves fabrication. The 4-foot-wide by 2-foot (1.2 m by 0.6 m) test specimen shall be constructed to fit into a 4-foot-wide (1.2 m) space at the top of the test assembly described in SFM 12-7A-1. Normal eave framing, joints in soffit material and other typical features present in the constructed assembly shall be present in the test specimen.
- Test Fixture. The test fixture shall be as described in SFM 12-7A-1, with the exception that the top soffit projection of the wall assembly fixture is modified to facilitate installation and removal of eave assemblies. Gypsum board (or equivalent) is used to create a noncombustible wall surface in the 4 x 8 ft. opening in the wall test fixture.
- Eaves assembly. Fit the eave assembly into the test module so that the horizontal surface of the assembly is 84 inches (2.1 m) from the top of the burner.
- Moisture content. Measure the moisture content of the wooden members of the assembly using a moisture meter (ASTM D4444), and for sheathing products, by methods outlined in ASTM D4442.
- Sealing. Seal the edges and ends with ceramic wool or comparable material to prevent flame penetration in these locations of the eave assembly.
12-7A-3.8 Conduct of Tests.
Airflow. The wall test shall be conducted under conditions of ambient airflow.
Number of tests. Conduct the tests on three replicate eaves assemblies.
Burner output verification. Without the eaves assembly in place, adjust the burner for 300 ± 15 kW output. Extinguish the burner.
Burner positioning. Center the burner with respect to the width of the eaves wall assembly and 0.75 inch (20 mm) from the wall. The distance from the floor to the top of the burner shall be 12 inches (300 mm).
Procedure.
CWUIC § 12-7 High relevance — show source text
SFM STANDARD 12-7A-3
12-7A-3.1 Application. The minimum design, construction and performance standards set forth herein for the exposed underside of horizontal projections such as the horizontal soffits of roof eaves, floor projections and exposed underfloor areas 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-3.2 Scope. This standard evaluates the fire-resistive performance of horizontal projection assemblies including the horizontal soffits of roof eaves, floor projections and exposed underfloor areas when subjected to direct flame exposure to the underside of a horizontal projection.
12-7A-3.3 Referenced documents.
ASTM D4442, Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials.
ASTM D4444, Test Methods for Use and Calibration of Hand-Held Moisture Meters.
California Building Code, Chapter 7A.
12-7A-3.4 Definitions.
- Eaves. A projecting edge of a roof that extends beyond the supporting wall as in CBC 702A “Roof Eave” or similar horizontal projection assembly.
- Soffit. The enclosed underside of any exterior overhanging section of a roof eave or similar horizontal projection assembly (see CBC 702A “Roof Eave Soffit”).
12-7A-3.5 Equipment.
- Burner. A 12 by 12-inch (300 by 300 mm) diffusion burner shall be used. Natural gas, methane or propane shall be supplied to the burner through a metered control system. The gas supply to the burner shall produce a net heat output of 300 ± 15 kW throughout the flame exposure. Burner output can be determined from HRR or calculated from the gas flow rate, temperature and pressure.
- Infrared temperature analyzer (optional). Intended for monitoring the temperature change of the inside of the eaves.
- Moisture content. Prior to testing, all materials (lumber and soffit material) shall be conditioned to a constant weight or for a minimum of 30 days at 73 ± 4°F (23 ± 2°C) and 50 ± 5% relative humidity, whichever occurs first. Constant weight shall be defined as occurring when the change in test material weight is less than or equal to 2 percent in a 24-hour period. Lumber moisture content shall be between 8 and 12 percent (oven-dry basis) and sheathing shall not exceed 8 percent (oven-dry basis).
12-7A-3.6 Materials.
Framing. The materials used shall be representative of the grades that would be typical of eave construction and installed in the eave’s subassembly as per accepted construction practices.
Soffit. Material selected for the test.
12-7A-3.7 Test system preparation (Figure 1).
- Eaves fabrication. The 4-foot-wide by 2-foot (1.2 m by 0.6 m) test specimen shall be constructed to fit into a 4-foot-wide (1.2 m) space at the top of the test assembly described in SFM 12-7A-1.
Frequently asked questions
Who can perform these tests?
A qualified fire‑testing laboratory capable of conducting ASTM E2957 or SFM 12‑7A‑3 should run the tests; the test report must document specimen construction, conditioning, burner verification and results as required in the standards and SFM reporting requirements .
If one specimen fails, can I “average” the results?
No. If one of the initial three specimens fails, you must perform three additional tests and all three additional tests must pass for the assembly to be accepted under the code (§ 504.7.2) .
Does passing the test let me use combustible materials?
Passing the test allows that specific boxed‑in assembly to be used as an alternative to the prescriptive noncombustible/ignition‑resistant options listed in § 504.3/§ 504.7 — but only for the tested assembly as built and conditioned; you cannot assume different materials or construction details will perform identically without testing .
How long is the observation after exposure?
The standard procedure continues monitoring after the exposure for an additional period so that the total test/observation runs to about 40 minutes; the absence of sustained combustion at the conclusion of the 40‑minute test is an acceptance requirement .
Can I rely on a manufacturer’s data sheet instead of the test report?
No. The code requires test results tied to the specific assembly construction and specimen details evaluated under ASTM E2957 or SFM 12‑7A‑3. The test report must document specimen construction, moisture condition, burner verification, times and locations of any penetration and other observations .
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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