CWUIC · California Wildland-Urban Interface Code
Which standards cover exterior wall direct‑flame and penetration tests?
The CWUIC lets you demonstrate exterior wall resistance to wildfire either by using noncombustible / prescriptive construction or by testing. The code accepts the ASTM E2707 direct‑flame penetration test (with strict replicate and pass/fail rules in **§ 504.9.3**) or the State Fire Marshal’s SFM 12‑7A‑1 method; where a 1‑hour rating is required, use ASTM E119 or UL 263 as noted in **§ 501.3**.
Last reviewed: July 6, 2026
What the code requires — plain English
- The California Wildland‑Urban Interface Code requires certain exterior wall assemblies to either be noncombustible, 1‑hour fire‑resistance rated, or to pass a direct‑flame exterior wall test. See § 504.5 for the list of acceptable methods.
- For exterior doors and claddings, the code accepts assemblies tested to ASTM E2707 or the State Fire Marshal 12‑7A‑1 method; the specific pass/fail conditions for ASTM E2707 are stated in § 504.9.3.
- When a 1‑hour fire‑resistance rating is required by the CWUIC, the rating must be determined using ASTM E119 or UL 263 per § 501.3.
The single most important rule: exterior wall systems intended to resist direct flame impingement must either meet prescribed noncombustible/fire‑resistance options or pass the ASTM E2707 (or SFM 12‑7A‑1) direct‑flame test with the acceptance criteria in § 504.9.3.
Requirements in detail
Which test standards are referenced by the CWUIC
- ASTM E2707 — Standard Test Method for Determining Fire Penetration of Exterior Wall Assemblies Using a Direct Flame Impingement Exposure. This is specifically cited as an accepted test route for exterior wall assemblies and for exterior surface/cladding acceptance under door rules. See § 504.5, § 504.9, § 504.9.3.
- SFM Standard 12‑7A‑1 (State Fire Marshal) — an alternate 10‑minute, 150 kW direct flame exposure test for exterior wall siding and sheathing that is accepted by the code (listed in § 504.5).
- ASTM E119 or UL 263 — used to establish 1‑hour fire‑resistance ratings where the CWUIC requires fire‑resistance‑rated construction per § 501.3.
Key test parameters and acceptance criteria (decision‑relevant)
| Decision‑relevant item | Value / threshold | Code Reference |
|---|---|---|
| Direct‑flame heat output (ASTM E2707 / SFM 12‑7A‑1) | 150 kW burner output (SFM 12‑7A‑1; ASTM E2707 uses equivalent direct flame impingement setup) | § 504.5, § 504.9, SFM 12‑7A‑1 |
| Direct‑flame exposure duration | 10 minutes exposure (then observation period) | § 504.5, SFM 12‑7A‑1 |
| Specimen size (wall assembly) | 4 ft × 8 ft assembly for direct flame wall test (SFM 12‑7A‑1 description) | SFM 12‑7A‑1 (referenced by § 504.5) |
| Minimum number of test replicates (ASTM E2707 acceptance in CWUIC) | 3 specimens minimum; if one fails, run 3 additional — all three additional must pass | § 504.9.3 |
| Primary pass criteria (ASTM E2707 as adopted) | Absence of flame penetration through the wall assembly at any time | § 504.9.3 |
| Secondary pass criterion (final observation) | Absence of glowing combustion on the interior (unexposed) surface at the end of the 70‑minute test | § 504.9.3 |
| 1‑hour fire‑resistance test standard | ASTM E119 or UL 263 to determine rating where required by code | § 501.3 |
Notes: ASTM E2707 is referenced directly by the CWUIC for exterior wall penetration testing and for exterior door/cladding acceptance; the CWUIC text ties the E2707 test and the SFM 12‑7A‑1 method to the acceptance routes in § 504.5 and § 504.9.
How ASTM E2707 is applied in the code (procedural points)
- The code requires three replicates run to the ASTM E2707 procedure; a single failed replicate triggers three additional tests and all three additional tests must pass for acceptance (see § 504.9.3).
- The two acceptance items in § 504.9.3 are absolute: no flame penetration at any time, and no evidence of glowing combustion on the inside surface at the end of the prescribed observation period.
Exceptions & special cases
- The CWUIC offers multiple alternative compliance paths for exterior walls in § 504.5: 1‑hour fire‑resistance rated construction, noncombustible materials, heavy timber, log wall construction, assemblies tested to SFM 12‑7A‑1, use of Type X gypsum sheathing behind the exterior cladding, and fire‑retardant‑treated wood labeled for exterior use. Choosing one of these alternatives avoids the need to perform ASTM E2707 for that wall. § 504.5 lists these explicitly.
- For doors, the code allows a 20‑minute fire protection rating when tested to NFPA 252, UL 10B, or UL 10C, or acceptance of the exterior surface/cladding when tested per ASTM E2707 (see § 504.9). Do not confuse the door fire‑rating tests (NFPA 252/UL10B/10C) with the E2707 wall penetration test — each standard addresses different performance attributes.
- When the code requires a 1‑hour rated assembly, the rating must be determined using ASTM E119 or UL 263 per § 501.3; prescriptive CBC solutions are an allowed exception as noted in § 501.3.
Common mistakes
- Mistake: assuming the ASTM E2707 exposure is the whole test window. Correction: the code requires the 10‑minute direct exposure but demands observation for sustained glowing up to the 70‑minute point for acceptance per § 504.9.3.
- Mistake: using a single replicate as proof of compliance. Correction: three replicates are required, and a failed replicate forces three additional tests per § 504.9.3.
- Mistake: treating ASTM E2707 as interchangeable with SFM 12‑7A‑1. Correction: both are accepted routes in the CWUIC, but SFM 12‑7A‑1 is the State Fire Marshal’s standard with its own apparatus/specimen descriptions (also cited in § 504.5). Confirm which test method the authority having jurisdiction (AHJ) requires.
- Mistake: assuming “no flaming on the interior” is enough. Correction: the code also requires no glowing combustion at the end of the observation period. Both criteria must be met (see § 504.9.3).
Worked example — a concrete scenario
Scenario: You propose to install a new composite siding system over wood studs with OSB sheathing (no additional Type‑X behind the siding). You want to use the ASTM E2707 pathway to demonstrate the wall assembly resists wildfire flame penetration.
Steps and numbers:
- Arrange testing to ASTM E2707 (or SFM 12‑7A‑1 if that is your chosen method) on a 4 ft × 8 ft representative assembly and confirm burner output is set to the prescribed 150 kW equivalent direct flame impingement (SFM description).
- Run 3 specimens. If all three show no flame penetration at any time, and no glowing on the interior at the end of the 70‑minute observation, the assembly meets the CWUIC acceptance via the ASTM E2707 route and satisfies § 504.5 / § 504.9.3.
- If one of the first three fails, run three additional replicates. Only if all three additional tests pass may the assembly be accepted under the ASTM E2707 route per § 504.9.3.
If the assembly cannot meet those test conditions, you must choose another compliance path from § 504.5 — for example, add a layer of 5/8‑inch Type X gypsum behind the siding (an accepted option listed in § 504.5) or use a 1‑hour rated assembly tested to ASTM E119 / UL 263 as required in § 501.3.
Related provisions in the CWUIC
- § 504.5 — Exterior walls: lists acceptable construction methods and explicitly references ASTM E2707 and SFM 12‑7A‑1.
- § 504.9 — Exterior doors: conditions for door construction and acceptance of exterior surface/cladding when tested to ASTM E2707.
- § 504.9.3 — Conditions of acceptance for ASTM E2707 (replicates, no penetration, no glowing at 70 minutes).
- § 501.3 — Fire‑resistance‑rated construction: use ASTM E119 or UL 263 to determine 1‑hour ratings.
- Referenced standards list (CWUIC / Referenced Standards): ASTME2707 and SFM 12‑7A‑1 appear in the CWUIC referenced standards tables (see the Referenced Standards listings).
Code references
Grounded in the retrieved California Wildland-Urban Interface Code — click a citation to read the verbatim passage:
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
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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 § 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
7-4 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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
2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 7-5
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
7-6 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CALIFORNIA WILDLAND-URBAN INTERFACE CODE – MATRIX ADOPTION TABLE
APPENDIX A – GENERAL REQUIREMENTS
CWUIC § 1.8 High relevance — show source text
403.1.8, 1273.10
ASTM ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959
D638—2022: Standard Test Method for Tensile Properties of Plastics
504.9.1
D2898—10(2017): Standard Practice for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing
503.2.4.3.1
D3909/D3909M— 2022 : Standard Specification for Asphalt Roll Roofing (Glass Felt) Surfaced With Mineral Granules
504.2.1.1, 504.2.2
D6662—22: Standard Specification for Polyolefin-Based Plastic Lumber Decking Boards
503.2.4.3.3
D7032—21: Standard Specification for Establishing Performance Ratings for Wood-Plastic Composite and Plastic Lumber Deck Boards, Stair Treads, Guards, and Handrails
503.2.4.3.2
E84— 2023d : Standard Test Method for Surface Burning Characteristics of Building Materials
202, 501.4.1, 503.2.4, 504.7.3.2, 504.7.3.3
E108—20a: Standard Test Methods for Fire Tests of Roof Coverings
504.2, 504.2.1.2, 504.11.6, G101.2.1
E119— 2022 : Standard Test Methods for Fire Tests of Building Construction and Materials
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
CWUIC § 504.9 High relevance — show source text
504.9 Exterior doors. Exterior doors shall be constructed in accordance with any of the following:
1. Noncombustible construction .
2. Solid-core wood not less than 1 [3] / 4 inches thick (44 mm) . 3. The exterior door shall be constructed of solid core wood that complies with the following requirements: 3.1. Stiles and rails shall not be less than 1 3/8 inches (35 mm) thick. 3.2. Raised panels shall not be less than 11/4 inches (32 mm) thick, except for the exterior perimeter of the raised panel that shall be permitted to taper to a tongue not less than 3/8 inch (10 mm) thick. 4. Have a fire protection rating of not less than 20 minutes when tested according to NFPA 252, UL 10B or UL 10C . 5. The exterior surface or cladding meeting the performance requirements of Section 504.9.3 when tested in accordance with ASTM E2707.
6. The exterior surface or cladding shall be tested to meet the performance requirements of SFM Standard 12-7A-1.
Windows within doors and glazed doors shall be in accordance with Section 504.8.
504.9.1 Garage doors. Automatic garage door openers for vehicle doors serving a residential building shall be equipped with a battery backup function.
504.9.2 Garage door perimeter gap. Exterior garage doors shall resist the intrusion of embers by preventing gaps between doors and door openings, at the bottom, sides and tops of doors, from exceeding [1] / 8 inch (3.2 mm). Gaps between doors and door openings shall be controlled by one or more of the following methods: 1. Weather-stripping products constructed of materials that which comply with both of the following: 1.1. The tensile strength of the material shall be tested in accordance with ASTM D638 before and after exposure to ASTM G155 for a period of 2,000 hours, and the maximum allowable difference in tensile strength values between exposed and nonexposed samples shall not exceed 10 percent. 1.2. When tested to UL 94, the materials shall have a flammability rating of V-2 or better. 2. Door overlaps onto jambs and headers. 3. Garage door jambs and headers covered with metal flashing.
504.9.3 Conditions of acceptance for ASTM E2707. The ASTM E2707 test shall be conducted 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 do 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 through the wall assembly at any time. 2. Absence of evidence of glowing combustion on the interior surface of the assembly at the end of the 70-minute test.
504.10 Vents. Where provided, ventilation openings for enclosed attics, gable ends, ridge ends, under eaves and cornices, enclosed eave soffit spaces, enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters, underfloor venti
5-8 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
CWUIC § 11.3.4 High relevance — show source text
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
252—2022: Standard on Fire Test of Door Assemblies
504.9
257—2022: Standard on Fire Test for Window and Glass Block Assemblies
504.8
CEC—2025: California Electrical Code
201.3
SFM State of California, Department of Forestry and Fire Protection, Office of the State Fire Marshal, P.O. Box 944246, Sacramento, CA 94246-2460
12-7A-1: Exterior Wall Siding and Sheathing. A fire resistance test standard consisting of a 150 kW intensity direct flame exposure for a 10-minute duration
504.5, 504.9
12-7A-2: Exterior Windows. A fire resistance test standard consisting of a 150 kW intensity direct flame exposure for an 8-minute duration
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
CWUIC § 12-7 High relevance — show source text
12-7A-1.2 Scope. This standard evaluates the performance of exterior walls of structures when exposed to direct flames.
12-7A-1.3 Referenced documents.
ASTM E2257, Test Method for Room Fire Test of Wall and Ceiling Materials and Assemblies.
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-1.4 Definitions.
- Siding (cladding). Any material that constitutes the exposed exterior covering of an exterior wall and is applied over sheathing or is directly attached to the wall structural system.
- Sheathing. The material placed on an exterior wall beneath cladding or siding and is directly attached to the wall structural system.
12-7A-1.5 Summary of test method.
- Direct flame exposure. This test method provides for the direct flame exposure of a wall specimen to a flame source centered at the base of a 4-foot by 8-foot (1220 mm by 2440 mm) test assembly.
- Gas burner. The method employs a gas burner to produce a diffusion flame in contact with the test wall assembly.
- Heat output. The gas burner produces a prescribed net rate of heat output of 8535 Btu/min (150 kW) for a period of 10 minutes, after which the flame exposure is terminated.
- Resistance to fire penetration. The test method measures the ability of the wall system to resist fire penetration from the exterior to the unexposed side of the test assembly under the conditions of exposure. Observations are made for the appearance of sustained flaming or glow on the unexposed side and/or sustained glowing on the unexposed side at the end of a 60-minute observation period.
12-7A-1.6 Equipment. Unless otherwise noted, dimensions in the following descriptions shall be followed with a tolerance of ± 0.5 inch (13 mm).
Wall assembly holding fixture. The test specimen support assembly shown in Figure 1 is designed to permit rapid installation and removal of wall assemblies, and to prevent edge penetration of fire at the margins of the wall assembly. It includes a sturdy frame assembly to hold the specimen and a simulated soffit that is noncombustible. The frame assembly permits a 4-foot by 8-foot (1220 mm by 2440 mm) prefabricated wall section to be inserted and to be sealed in such a way that protects the edges from fire. Side shields are situated near the vertical edges and to within 12 inches (304 mm) of the top of the test wall assembly as shown in Figure 1 to aid in minimizing extraneous drafts to the surface of the assembly.
Burner.
2.1. Burner details. The ignition source for the test shall be a gas diffusion burner with a nominal 4-inch-wide by 39-inchlong (100 mm wide by 1000 mm long) porous top surface of a refractory material, as shown in Figure 2. With the exception of top surface dimensions, the essential configuration of the burner is comparable to the burner design described in ASTM E2257. The burner enclosure shall be positioned so that it is centered relative to the width of the test wall.
CWUIC § 2303.2 High relevance — show source text
1. Noncombustible material.
2. Ignition-resistant building material. 3. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code. 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. 2-inch (51 mm) nominal dimension lumber. 6. One layer of [5] / 8 -inch (16 mm) Type X gypsum sheathing applied behind an exterior covering on the underside of the roof deck.
7. 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 roof deck designed for exterior fire exposure, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual.
2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 5-5
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
�
�
�
�
�
SPECIAL BUILDING CONSTRUCTION REGULATIONS
Facias, if provided, shall be of fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the Cali- fornia Building Code, ignition-resistant building materials, materials approved for not less than 1-hour fire-resistance-rated construction or 2-inch (51 mm) nominal dimension lumber.
504.4 Gutters and downspouts. Gutters and downspouts shall be constructed of noncombustible material. Gutters shall be provided with an approved means to prevent the accumulation of leaves and debris in the gutter.
504.5 Exterior walls. Exterior walls of buildings or structures shall be constructed with one or more of the following methods, unless they are covered with an exterior wall covering complying with Sections 504.5.2 and 504.5.2.1:
1-hour fire-resistance-rated construction on the exterior side.
Noncombustible materials.
Heavy timber. Assembly of sawn lumber or glue-laminated wood with the smallest minimum nominal dimension of 4 inches (102 mm). Sawn or glue-laminated planks splined, tongue-and-grove or set close together and well spiked. 4. Log wall construction. 5. Wall assemblies that have been tested in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in ASTM E2707 with the conditions of acceptance shown in Section 504.9.3. 6. Wall assemblies that meet the performance criteria in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in SFM Standard 12-7A-1. 7. Wall assemblies suitable for exterior fire exposure containing one layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind the exterior wall covering or cladding on the exterior side of the framing. 8. Wall assemblies suitable for exterior fire exposure with a 1-hour fire-resistance rating, rated from the exterior side, as tested in accordance with ASTM E119 or UL 263.
9. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code .
CWUIC § 12-7 High relevance — show source text
- When tested as follows, flames shall not reach the top edge of the specimen. The test shall be conducted in a draft free area, on a specimen of the material 12 inches by 12 inches (305 mm by 305 mm) suspended at a 45-degree angle from the horizontal with the upper and lower edges in a horizontal plane. The test flame shall be 3 inches (76 mm) long from a Bunsen burner of approximately [1] / 2 -inch (13 mm) inside diameter with the air supply completely shut off. The burner shall be positioned so that its top is 1 inch (25 mm) vertically below a point on the lower surface of the test specimen, 1 inch (25 mm) up from its lower horizontal edge and midway between the inclined edges. The exposure to the test flame and the duration of test shall be for a period of 2 minutes.
2025 CALIFORNIA REFERENCED STANDARDS CODE 35
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
36 2025 CALIFORNIA REFERENCED STANDARDS CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
12-7A MATERIALS AND CONSTRUCTION METHODS
FOR EXTERIOR WILDFIRE EXPOSURE
EXTERIOR WALL SIDING AND SHEATHING
SFM STANDARD 12-7A-1
12-7A-1.1 Application. The minimum design, construction and performance standards set forth herein for exterior wall siding and sheathing 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-1.2 Scope. This standard evaluates the performance of exterior walls of structures when exposed to direct flames.
12-7A-1.3 Referenced documents.
ASTM E2257, Test Method for Room Fire Test of Wall and Ceiling Materials and Assemblies.
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-1.4 Definitions.
- Siding (cladding). Any material that constitutes the exposed exterior covering of an exterior wall and is applied over sheathing or is directly attached to the wall structural system.
- Sheathing. The material placed on an exterior wall beneath cladding or siding and is directly attached to the wall structural system.
12-7A-1.5 Summary of test method.
- Direct flame exposure. This test method provides for the direct flame exposure of a wall specimen to a flame source centered at the base of a 4-foot by 8-foot (1220 mm by 2440 mm) test assembly.
- Gas burner. The method employs a gas burner to produce a diffusion flame in contact with the test wall assembly.
- Heat output. The gas burner produces a prescribed net rate of heat output of 8535 Btu/min (150 kW) for a period of 10 minutes, after which the flame exposure is terminated.
- Resistance to fire penetration. The test method measures the ability of the wall system to resist fire penetration from the exterior to the unexposed side of the test assembly under the conditions of exposure.
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
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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 § 504.5 High relevance — show source text
504.5 Exterior walls. Exterior walls of buildings or structures shall be constructed with one or more of the following methods, unless they are covered with an exterior wall covering complying with Sections 504.5.2 and 504.5.2.1:
1-hour fire-resistance-rated construction on the exterior side.
Noncombustible materials.
Heavy timber. Assembly of sawn lumber or glue-laminated wood with the smallest minimum nominal dimension of 4 inches (102 mm). Sawn or glue-laminated planks splined, tongue-and-grove or set close together and well spiked. 4. Log wall construction. 5. Wall assemblies that have been tested in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in ASTM E2707 with the conditions of acceptance shown in Section 504.9.3. 6. Wall assemblies that meet the performance criteria in accordance with the test procedures for a 10-minute direct flame contact exposure test set forth in SFM Standard 12-7A-1. 7. Wall assemblies suitable for exterior fire exposure containing one layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind the exterior wall covering or cladding on the exterior side of the framing. 8. Wall assemblies suitable for exterior fire exposure with a 1-hour fire-resistance rating, rated from the exterior side, as tested in accordance with ASTM E119 or UL 263.
9. Fire-retardant-treated wood labeled for exterior use and complying with Section 2303.2 of the California Building Code .
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.
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
2025 CALIFORNIA REFERENCED STANDARDS CODE 41
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE
HORIZONTAL PROJECTION UNDERSIDE
SFM STANDARD 12-7A-3
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
2025 CALIFORNIA REFERENCED STANDARDS CODE 41
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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.
Frequently asked questions
Is ASTM E2707 the only test I can use to show a wall resists direct flame?
No. The CWUIC accepts either testing to ASTM E2707 or compliance with the State Fire Marshal’s 12‑7A‑1 method, or alternative construction routes listed in § 504.5 (noncombustible, 1‑hour rating, Type X gypsum behind cladding, heavy timber, etc.).
How many specimens are required and what if one fails?
Run 3 specimens. If any one fails, you must run 3 additional tests — and all three additional tests must pass for acceptance under § 504.9.3.
What exactly is "no glowing combustion" and when is it checked?
“No glowing combustion” means there is no evidence of smoldering/glowing on the unexposed (interior) surface at the end of the observation period (the CWUIC references a 70‑minute observation requirement in its conditions of acceptance). See § 504.9.3.
If I have a 1‑hour fire‑rated exterior wall do I still need ASTM E2707?
No. A 1‑hour exterior fire‑resistance rating determined by ASTM E119 or UL 263 satisfies the CWUIC requirement as an alternative compliance path in § 504.5 and per § 501.3.
Who decides whether E2707 or SFM 12‑7A‑1 is acceptable?
The authority having jurisdiction (AHJ) enforces the code; confirm with the AHJ whether a submitted test report (ASTM E2707 or SFM 12‑7A‑1) and testing laboratory meet local acceptance criteria. The CWUIC itself lists both methods as accepted standards.
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)
Ask about the CWUIC
Get cited, plain-English answers on the California Wildland-Urban Interface Code for your project — any code section, any scenario.
Start Free Trial