CWUIC · California Wildland-Urban Interface Code
How are noncombustible materials and fire‑retardant‑treated wood defined and tested?
In plain terms: the CWUIC says a material can only be called “noncombustible” if it actually passes the ASTM E136 test (or an equivalent ASTM E2652 report judged by E136 criteria) and that **fire‑retardant‑treated wood** used outside must be specifically certified for exterior use and meet the California Building Code rules referenced in **§ 503.2.2**. Always get the manufacturer’s test report and check for the specific exceptions (like thin surfacings over noncombustible bases) noted in **§ 501.4** and **§ 501.4.1**.
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
The CWUIC requires that materials designated noncombustible must meet standardized test criteria and actually pass those tests before they can be treated as noncombustible for exterior construction. See § 501.4 and § 501.4.1 for the acceptance tests (ASTM E136 or ASTM E2652 using ASTM E136 acceptance criteria) and the limits on applying the “noncombustible” label. Fire‑retardant‑treated wood used on the exterior must be identified for exterior use and comply with the California Building Code requirement referenced in § 503.2.2.
The single most important rule: materials required to be noncombustible must be tested and shown to meet the ASTM E136 criteria (or ASTM E2652 with E136 acceptance criteria); fire‑retardant‑treated wood for exterior use must be identified for exterior use and meet CBC Section 2303.2 as required by § 503.2.2.
Requirements in detail
What “noncombustible” means and how it is proven
Noncombustible building materials required by the CWUIC must be tested in accordance with ASTM E136 and pass that test. Alternatively, the material may be tested under ASTM E2652 and accepted if the E2652 results meet the acceptance criteria prescribed by ASTM E136. This acceptance/testing requirement is established in § 501.4.1 and is invoked by § 501.4.
The code also states that the term noncombustible does not apply to the flame‑spread characteristics of interior finish or trim materials, and that a material will not be classified as noncombustible if its combustibility or flame spread increases (for example through weathering, moisture, or aging) beyond the code limitations. § 501.4 explains this limitation.
What the CWUIC requires for fire‑retardant‑treated wood
- Fire‑retardant‑treated wood used for exterior building components must be identified for exterior use and must comply with the California Building Code requirements referenced in § 503.2.2 (specifically CBC Section 2303.2). The CWUIC does not restate CBC 2303.2; it requires compliance with that CBC section. If you need the technical acceptance criteria for exterior FRT wood, consult CBC § 2303.2 directly (that CBC text was not supplied in the CWUIC files provided here).
Key decision dimensions (quick reference table)
| Decision factor | What to check / required value | Code Reference |
|---|---|---|
| Test method to prove noncombustible | ASTM E136 (primary) OR ASTM E2652 using the acceptance criteria of ASTM E136 | § 501.4.1 |
| Whether “noncombustible” applies to interior finish/trim | Does not apply to flame‑spread of interior finish/trim | § 501.4 |
| Materials that lose classification due to aging/weathering | Material is disqualified as noncombustible if combustibility/flame spread increases beyond limits due to age/moisture/etc. | § 501.4 |
| Exterior fire‑retardant‑treated wood | Must be identified for exterior use and comply with CBC § 2303.2 (see local plan reviewer for acceptable documentation) | § 503.2.2 |
| Exception — surfacing over noncombustible base | Surface up to 0.125 inch (3.18 mm) thick with flame spread ≤ 50 (ASTM E84/UL 723) over a structurally noncombustible base may be acceptable as noncombustible | § 501.4 (exception) |
Exceptions & special cases
Exception for composite surfaces: A material with a structural base of noncombustible material (as determined by ASTM E136 or ASTM E2652 with E136 criteria) and a surfacing no thicker than 0.125 inch (3.18 mm) having a flame spread index ≤ 50 when tested to ASTM E84/UL 723 is treated as acceptable as noncombustible. That exception is part of § 501.4.
Panels or assemblies with combustible cores but noncombustible exterior facings may be subject to other test/exemption rules in Chapter 5 (for example, certain metal facings have minimum thicknesses cited elsewhere in Chapter 5). Always confirm whether a particular panel falls into an exception or must be tested. (The CWUIC references these assembly/test rules in Chapter 5; see related provisions below.)
For fire‑retardant‑treated wood, the CWUIC delegates the technical acceptance/identification criteria to CBC Section 2303.2 (per § 503.2.2). The CWUIC requires identification for exterior use but does not reproduce the detailed CBC acceptance tests — retrieve CBC § 2303.2 for specifics.
Common mistakes
Assuming a visually “noncombustible” appearance equals code compliance — the material must have the appropriate test report (ASTM E136 or ASTM E2652 with E136 acceptance). Do not accept vendor claims without documented test evidence.
Using interior‑rated fire‑retardant‑treated wood outdoors. The CWUIC requires FRT wood to be identified for exterior use — interior‑only FRT products will not meet § 503.2.2.
Overlooking the exception: some thin surfacings over a verified noncombustible base may be acceptable; conversely, assuming every thin facing qualifies can lead to incorrect approvals. Check surfacing thickness (≤ 0.125 inch / 3.18 mm) and flame spread (≤ 50).
Not accounting for future degradation: materials that initially pass noncombustible tests but are likely to change properties with age, moisture or weathering cannot be treated as noncombustible under § 501.4.
Worked example — siding decision (concrete numbers)
Scenario: A designer wants to use a 0.10‑inch decorative veneer glued to a cement‑based panel as exterior siding in a WUI area.
Does the veneer + panel assembly qualify as noncombustible?
- Step 1: Confirm the structural base is noncombustible (cement‑based panel). If the base meets ASTM E136 (or E2652 accepted to E136 criteria), that satisfies the base requirement in the exception to § 501.4.
- Step 2: Measure the veneer thickness: 0.10 inch = ≤ 0.125 inch (3.18 mm) — this meets the surfacing thickness limit in the exception.
- Step 3: Obtain a flame‑spread test for the veneer surface (ASTM E84/UL 723). If the veneer’s flame spread index is ≤ 50, then under the exception the assembly may be accepted as noncombustible per § 501.4.
If the veneer were 0.20 inch thick or had a flame spread index of 70, the exception would not apply — the product would need demonstration of compliance via ASTM E136 (or ASTM E2652 using E136 acceptance criteria) on the complete assembly or a manufacturer test demonstrating equivalence per § 501.4.1.
For any wood used on the exterior (e.g., trim), verify that any fire‑retardant‑treated wood is identified for exterior use and confirm it meets CBC § 2303.2 as required by § 503.2.2; if not, it is not acceptable for exterior ignition‑resistant construction.
Related provisions
- § 501.3 — Fire‑resistance‑rated construction; references ASTM E119/UL 263 for fire‑resistance ratings.
- § 503.2.1 — Noncombustible material requirement points to § 501.4 for the test criteria.
- § 503.2.3 — Fire‑retardant‑treated wood roof coverings (references CBC § 1505.6 and classification requirements).
- § 503.2.4 — Other ignition‑resistant materials (extended ASTM E84/UL 723 or ASTM E2768 testing and panel test details). This section contains additional test and panel‑gap provisions for combustible panels used on exteriors.
Code references
Grounded in the retrieved California Wildland-Urban Interface Code — click a citation to read the verbatim passage:
CWUIC § 0.125 High relevance — show source text
Exception: Materials having a structural base of noncombustible material as determined in accordance with ASTM E136, or with ASTM E2652 using the acceptance criteria prescribed by ASTM E136, and a surfacing of not more than 0.125 inch (3.18 mm) in thick- ness having a flame spread index not greater than 50 when tested in accordance with ASTM E84 or UL 723 shall be acceptable as noncombustible.
SECTION 502— RESERVED
SECTION 503—IGNITION-RESISTANT CONSTRUCTION AND MATERIAL
503.1 General. Buildings and structures hereafter constructed, modified or relocated into or within wildland-urban interface areas shall meet the construction requirements in accordance with Chapter 5 . Materials required to be ignition-resistant building materials shall comply with the requirements of Section 503.2.
Exceptions:
1. New accessory buildings and miscellaneous structures complying with Section 504.11. 2. Additions to and remodels of buildings originally constructed prior to July 1, 2008. 3. Group C occupancy special buildings conforming to the limitations specified in Section 450.4.1 of the California Building Code.
503.2 Ignition-resistant building material. Ignition-resistant building materials shall be designed for exterior use and weather expo- sure and shall comply with any one of the requirements in Section 503.2.1 through 503.2.4.3.3 .
503.2.1 Noncombustible material. Noncombustible material shall comply with the requirements in Section 501.4 .
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503.2.2 Fire-retardant-treated wood. Fire-retardant-treated wood shall be identified for exterior use and shall meet the requirements of Section 2303.2 of the California Building Code .
503.2.3 Fire-retardant-treated wood roof coverings. Roof assemblies containing fire-retardant-treated wood shingles and shakes shall comply with the requirements of Section 1505.6 of the California Building Code and shall be classified as Class A roof assemblies as required in Section 1505.2 of the California Building Code .
503.2.4 Other ignition-resistant building material. Material shall be tested on the front and back faces in accordance with the extended ASTM E84 or UL 723 test, for a total test period of 30 minutes, or with the ASTM E2768 test. The materials shall bear identification showing the fire test results. Panel products shall be tested with a ripped or cut longitudinal gap of [1] / 8 inch (3.2 mm). The materials, when tested in accordance with the test procedures set forth in ASTM E84 or UL 723 for a test period of 30 minutes, or with ASTM E2768, shall comply with Sections 503.2.4.1 through 503.2.4.3.
Exception: Materials composed of a combustible core and a noncombustible exterior covering made from either aluminum at a minimum 0.019 inch (0.48 mm) thickness or corrosion-resistant steel at a minimum 0.0149 inch (0.38 mm) thickness shall not be required to be tested with a ripped or cut longitudinal gap.
CWUIC § 504.7 High relevance — show source text
504.7 Projections . Unenclosed accessory structures attached to buildings with habitable spaces and projections, other than decks, shall be heavy timber construction or constructed of one of the following:
Noncombustible materials.
Fire-retardant-treated wood identified for exterior use and meeting the requirements of Section 2303.2 of the California Building Code .
Ignition-resistant building materials in accordance with Section 503.2. 4. Materials approved for not less than 1-hour fire-resistance-rated construction on the exterior side, as tested in accordance with ASTM E119 or UL 263.
5. One layer of [5] / 8 -inch (15.9 mm) Type X gypsum sheathing applied behind the exterior covering on the underside of the ceiling. 6. The exterior portion of a 1-hour fire-resistance-rated exterior assembly, as tested in accordance with ASTM E119 or UL 263, applied to the underside of the ceiling assembly, including assemblies using the gypsum panel and sheathing products listed in the Gypsum Association Fire Resistance Design Manual. 7. The underside of a floor projection assembly that meets the performance criteria in Section 504.7.2 when tested in accordance with the test procedures set forth in ASTM E2957.
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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.
CWUIC § 5-1 High relevance — show source text
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5 SPECIAL BUILDING CONSTRUCTION REGULATIONS
User notes:
About this chapter: Chapter 5 provides regulations that establish minimum standards for the location, design and construction of buildings and structures based on construction within a Fire Hazard Severity Zone or a Wildland-Urban Interface (WUI) Area.
The construction provisions of Chapter 5 are intended to supplement the requirements of the California Building Code and California Residential Code and address mitigation of the unique hazards posed to buildings by wildfire and to reduce the hazards of building fires spreading to wildland fuels. This is accomplished by requiring ignition-resistant construction materials. Construction features regulated include underfloor areas; roof coverings; eaves and soffits; gutters and downspouts; exterior walls, doors and windows; ventilation openings and accessory structures.
SECTION 501—GENERAL
501.1 Scope. Buildings and structures in a wildland-urban interface area shall be constructed in accordance with the California Build- ing Code and this code.
Exceptions:
- Group U accessory structures not exceeding 120 square feet (11 m [2] ) in floor area where located not less than 50 feet (15 240 mm) from applicable buildings.
- Group U agricultural buildings not less than 50 feet (15 240 mm) from applicable buildings.
501.2 Objective. The objective of this chapter is to establish minimum standards to locate, design and construct buildings and structures or portions thereof for the protection of life and property, to resist damage from wildfires, and to mitigate building and structure fires from spreading to wildland fuels.
501.3 Fire-resistance-rated construction. Where this code requires 1-hour fire-resistance-rated construction, the fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E119 or UL 263.
Exceptions:
- The fire-resistance rating of building elements, components or assemblies based on the prescriptive designs prescribed in Section 721 of the California Building Code .
- The fire-resistance rating of building elements, components or assemblies based on the calculation procedures in accordance with Section 722 of the California Building Code .
501.4 Noncombustibility tests. The tests indicated in Section 501.4.1 shall serve as criteria for acceptance of noncombustible building materials. The term “noncombustible” does not apply to the flame spread characteristics of interior finish or trim materials. A material shall not be classified as a noncombustible building construction material if it is subject to an increase in combustibility or flame spread beyond the limitations herein established through the effects of age, moisture or other atmospheric conditions.
501.4.1 Noncombustible materials. Materials required to be noncombustible shall be tested in accordance with ASTM E136 and pass the test. Alternately, materials required to be noncombustible shall be tested in accordance with ASTM E2652 using the accep- tance criteria prescribed by ASTM E136.
CWUIC § 3.2 Medium relevance — show source text
3.2|||||||| |404.4|Hydrants|Y|||507.5|||||| |404.5|Adequate water
supply|Y|||507.3|1275.02(b)||||| |404.6|Reserved|N||||||||| |404.7|Obstructions|Y|||507.5.4|||||| |404.8|Identification|Y||||1275.04(a)||||| |404.9|Testing and
maintenance|Y|||507.5.2|||||| |404.10|Reliability|Y|||507.5.2|||||| |404.10.1|Objective|Y|404.10.1|||||||| |404.10.2|Clearance of fuel|Y|||4907.1|||||| |404.10.3|Standby power|Y|||507.5.2|||||| |Chapter 5|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations| |501|General|Y||701A||||||| |501.1|Scope|Y||701A.3||||||| |501.2|Objective|Y||701A.2||||||| |501.3|Fire-resistance-rated
construction|Y||703.2.1.5||||||| |501.4|Noncombustibility
tests|Y||703.3||||||| |501.4.1|Noncombustible
materials|Y||703.3.1||||||| |502|RESERVED|N||||||||| |503|Ignition-resistant
construction and
material|Y||704A||||||| |503.1|General|Y||701A.3||||||| |503.2|Ignition-resistant
building material|Y||707A.3 #2||||||| |503.2.1|Noncombustible
material|Y||704A.4 #1||||||| |503.2.2|Fire-retardant-
treated wood|Y||704A.4 #2||||||| |503.2.3|Fire-retardant-
treated wood roof
coverings|Y||705A.1||||||| |503.2.4|Other ignition-
resistant building
material|Y||704A.3||||||| |503.2.4.1|Flame spread|Y||704A.3 #1||||||| |503.2.4.2|Flame front|Y||704A.3 #2||||||| |503.2.4.3|Weathering|Y||703A.5.1||||||| |503.2.4.3.1|Evaluation require-
ments for weathering|Y||703A.5.2
703A.5.2.1||||||| |503.2.4.3.2|Wood-plastic
composite materials|Y||703A.6|||||||APPENDIX H-28 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
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APPENDIX H—REFERENCED CALIFORNIA DOCUMENTS
CWUIC § 1.5 Medium relevance — show source text
Division 1.5
Section|Title 19,
Division 1
Section|Gov Code
Section|PRC
Section|HSC
Section| |---|---|---|---|---|---|---|---|---|---|---| |Section|Title|Title|Title|Title|Title|Title|Title|Title|Title|Title| |Chapter 4|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements| |403.2.5|Address installation,
location, and visibility|Y||||1274.04(a)
1274.04(b)
1274.04(c)
1274.04(d)
1274.04(e)
1274.04(f)||||| |404|Water supply|Y||||1275.02||||| |404.1|General|Y|||507|1275.02(b)||||| |404.2|Required water supply|Y||||1275.02(c)||||| |404.3|Draft sites|Y||||||||| |404.3.1|Access|Y|||507.5.4|||||| |404.3.2|Pumper access points|Y|404.3.2|||||||| |404.4|Hydrants|Y|||507.5|||||| |404.5|Adequate water
supply|Y|||507.3|1275.02(b)||||| |404.6|Reserved|N||||||||| |404.7|Obstructions|Y|||507.5.4|||||| |404.8|Identification|Y||||1275.04(a)||||| |404.9|Testing and
maintenance|Y|||507.5.2|||||| |404.10|Reliability|Y|||507.5.2|||||| |404.10.1|Objective|Y|404.10.1|||||||| |404.10.2|Clearance of fuel|Y|||4907.1|||||| |404.10.3|Standby power|Y|||507.5.2|||||| |Chapter 5|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations|Special building construction regulations| |501|General|Y||701A||||||| |501.1|Scope|Y||701A.3||||||| |501.2|Objective|Y||701A.2||||||| |501.3|Fire-resistance-rated
construction|Y||703.2.1.5||||||| |501.4|Noncombustibility
tests|Y||703.3||||||| |501.4.1|Noncombustible
materials|Y||703.3.CWUIC § 8.1 Medium relevance — show source text
8.1_ –504.8.2|||X||||||||||||||||||||| |504.9|||X||||||||||||||||||||| |504.9.1 –504.9.3|||X||||||||||||||||||||| |504.10.1 – 504.10.3|||X||||||||||||||||||||| |504.11 – 504.11.1|||X||||||||||||||||||||| |504.11.2 –504.11.6|||X||||||||||||||||||||| |505 – 506_Reserved_|||X||||||||||||||||||||| |507.1|||X|||||||||||||||||||||
- The California Code of Regulations (CCR), Title 19, Division 1 provisions that are found in the California Wildland-Urban Interface Code are a reprint from the current CCR, Title 19, Division 1 text for the code user’s convenience only. The scope, applicability and appeals procedures of CCR, Title 19, Division I remain the same. The state agency does not adopt sections identified by the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
The California Code of Regulations (CCR), Title 14, Division 1.5 provisions that are found in the California Wildland-Urban Interface Code are not listed in the Matrix Adoption Tables as they are not within the State Fire Marshal’s authority to adopt. These provisions are a reprint from the current CCR, Title 14, Division 1.5 text for the code user’s convenience only and are identified in the body of the code by square brackets containing references to applicable Title 14 sections.
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5 SPECIAL BUILDING CONSTRUCTION REGULATIONS
User notes:
About this chapter: Chapter 5 provides regulations that establish minimum standards for the location, design and construction of buildings and structures based on construction within a Fire Hazard Severity Zone or a Wildland-Urban Interface (WUI) Area.
The construction provisions of Chapter 5 are intended to supplement the requirements of the California Building Code and California Residential Code and address mitigation of the unique hazards posed to buildings by wildfire and to reduce the hazards of building fires spreading to wildland fuels. This is accomplished by requiring ignition-resistant construction materials. Construction features regulated include underfloor areas; roof coverings; eaves and soffits; gutters and downspouts; exterior walls, doors and windows; ventilation openings and accessory structures.
SECTION 501—GENERAL
501.1 Scope. Buildings and structures in a wildland-urban interface area shall be constructed in accordance with the California Build- ing Code and this code.
Exceptions:
- Group U accessory structures not exceeding 120 square feet (11 m [2] ) in floor area where located not less than 50 feet (15 240 mm) from applicable buildings.
- Group U agricultural buildings not less than 50 feet (15 240 mm) from applicable buildings.
CWUIC § 1.11. Medium relevance — show source text
- The California Code of Regulations (CCR), Title 19, Division 1 provisions that are found in the California Wildland-Urban Interface Code are a reprint from the current CCR, Title 19, Division 1 text for the code user’s convenience only. The scope, applicability and appeals procedures of CCR, Title 19, Division I remain the same. The state agency does not adopt sections identified by the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
The California Code of Regulations (CCR), Title 14, Division 1.5 provisions that are found in the California Wildland-Urban Interface Code are not listed in the Matrix Adoption Tables as they are not within the State Fire Marshal’s authority to adopt. These provisions are a reprint from the current CCR, Title 14, Division 1.5 text for the code user’s convenience only and are identified in the body of the code by square brackets containing references to applicable Title 14 sections.
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A GENERAL REQUIREMENTS
The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance.
User notes:
About this appendix: Appendix A, while not part of the code, can become part of the code when specifically included in the adopting ordinance. Its purpose is to provide fire protection measures supplemental to those found in Chapter 6 to reduce the threat of wildfire in a wildland-urban interface area and improve the capability for controlling such fires. This appendix includes detailed requirements for vegetation control; the code official’s authority to close wildland-interface areas in times of high fire danger; control of fires, fireworks usage and other sources of ignition; storage of hazardous materials and combustibles; bans on the dumping of waste materials and ashes and coals in wildland-urban interface areas; protection of pumps and water supplies; and limits on temporary uses within the wildland-urban interface area.
SECTION A101—GENERAL
A101.1 Scope. The provisions of this appendix establish general requirements applicable to new and existing properties located within wildland-urban interface areas .
A101.2 Objective. The objective of this appendix is to provide necessary fire protection measures to reduce the threat of wildfire in a wildland-urban interface area and improve the capability of controlling such fires.
SECTION A102—VEGETATION CONTROL
A102.1 General. Vegetation control shall comply with Sections A102.2 through A102.4.
A102.2 Clearance of brush or vegetative growth from roadways. The code official is authorized to require areas within 10 feet (3048 mm) on each side of portions of fire apparatus access roads and driveways to be cleared of nonfire-smart vegetation growth.
Exception: Single specimens of trees, ornamental vegetative fuels or cultivated ground cover, such as green grass, ivy, succulents or similar plants used as ground cover, provided they do not form a means of readily transmitting fire.
CWUIC § 3-3 Medium relevance — show source text
301 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
302 Wildland-Urban Interface Area Designations . . . . . .3-3
CHAPTER 4 WILDLAND-URBAN INTERFACE AREA
REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . 4-3
401 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
402 Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
403 Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
404 Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
CHAPTER 5 SPECIAL BUILDING CONSTRUCTION
REGULATIONS . . . . . . . . . . . . . . . . . . . . . . . . 5-3
501 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3
502 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3
503 Ignition-Resistant Construction and Material. . . . . .5-3
504 Ignition-Resistant Construction. . . . . . . . . . . . . . . . . .5-4
505 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-9
506 Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-9
507 Replacement or Repair of Roof Coverings. . . . . . . . .5-9
CHAPTER 6 FIRE PROTECTION REQUIREMENTS. . . . . . .6-3
601 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
602 Fire Protection Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
603 Vegetation Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
604 Maintenance of Defensible Space . . . . . . . . . . . . . . . 6-5
CWUIC § 201.3 Medium relevance — show source text
Adopting Agency BSC BSC-
CGSFM Col5 HCD Col7 Col8 DSA Col10 OSHPD Col12 Col13 Col14 Col15 Col16 BSCC DPH AGR DWR CEC CA SL SLC Adopting Agency BSC BSC-
CGT-24 T-19* 1 2 1/AC AC SS 1 1R 2 3 4 5 5 5 5 5 5 5 5 5 Adopt Entire Chapter Adopt Entire Chapter as
amended (amended sections
listed below)X Adopt only those sections that
are listed below[California Code of Regulations,
Title 19, Division 1]Chapter / Section 201.3 X Applicable Building X Defensible Space X Exterior Wall Assembly X Exterior Wall Covering X Fire Code Official X Fire Hazard Severity Zones X Fire Protection Plan X Fire-Smart Vegetation X Flame Spread Index X Fuel X Fuel Modification X Local Responsibility Area (LRA) X Rafter Tail X Roof Eave X Roof Eave Soffit X State Responsibility Area (SRA) X Structure X Wildfire X Wildfire Exposure X Wildland-Urban Interface Area X - The California Code of Regulations (CCR), Title 19, Division 1 provisions that are found in the California Wildland-Urban Interface Code are a reprint from the current CCR, Title 19, Division 1 text for the code user’s convenience only. The scope, applicability and appeals procedures of CCR, Title 19, Division I remain the same. The state agency does not adopt sections identified by the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
CWUIC § 1270.01 Medium relevance — show source text
1|||||| ||Strategic
ridgeline (T14)|Y||||1270.01(dd)||||| ||Structure|Y|202|||1270.01(ee)||||| ||Subdivision|Y||||||||| ||Tree crown|Y||||||||| ||Undeveloped
ridgeline (T14)|Y||||1270.01(ii)||||| ||Unenclosed acces-
sory structure|Y||||||||| ||Vertical curve (T14)|Y||||1270.01(k)||||| ||Wildfire|Y||702A|4902.1|||||| ||Wildfire exposure|Y||702A|4902.1|||||| ||Wildland|Y||||||||| ||Wildland-urban inter-
face area|Y||702A|4902.1|||||| |Chapter 3|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas|Wildland-urban interface areas| |301|General|Y||||||||| |301.1|Scope|Y||||||||4201| |301.2|Purpose|Y|||||||51176|4201| |302|Wildland-Urban
Interface Area
Designations|Y||||||||| |302.1|Mapping|Y|||4904.2||||51178|4202
4203(a)
4204| |302.2|Review of wildland-
urban interface areas|Y|||||||51181|4204| |Chapter 4|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements|Wildland-urban interface area requirements| |401|General|Y||||||||| |401.1|Scope|Y||||||||| |401.2|Objective|Y||||1273.00||||| |401.3|General safety
precautions|Y||||||||| |402|Applicability|Y|||||||||APPENDIX H-26 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
APPENDIX H—REFERENCED CALIFORNIA DOCUMENTS
|2025 CWUIC—continued|Col2|Adopted
Yes/No|IWUIC
Section|CBC
Section|CFC
Section|Title 14,
Division 1.5
Section|Title 19,CWUIC § 104.6 Medium relevance — show source text
3|||X||||||||||||||||||||| |104.6|||X||||||||||||||||||||| |104.8|||X||||||||||||||||||||| |104.8.1|||X||||||||||||||||||||| |105.1|||X||||||||||||||||||||| |105.2|||X||||||||||||||||||||| |105.3|||X||||||||||||||||||||| |105.4|||X||||||||||||||||||||| |105.8|||X||||||||||||||||||||| |105.10|||X||||||||||||||||||||| |106.1 – 106.5|||X||||||||||||||||||||| |106.8|||X||||||||||||||||||||| |106.10|||X||||||||||||||||||||| |107|||X||||||||||||||||||||| |109.1 – 109.1.2.3|||X||||||||||||||||||||| |109.3.7.1|||X||||||||||||||||||||| |109.3.7.2|||X||||||||||||||||||||| |110 – 111|||X||||||||||||||||||||| |113|||X|||||||||||||||||||||
- The California Code of Regulations (CCR), Title 19, Division 1 provisions that are found in the California Wildland-Urban Interface Code are a reprint from the current CCR, Title 19, Division 1 text for the code user’s convenience only. The scope, applicability and appeals procedures of CCR, Title 19, Division I remain the same. The state agency does not adopt sections identified by the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
The California Code of Regulations (CCR), Title 14, Division 1.5 provisions that are found in the California Wildland-Urban Interface Code are not listed in the Matrix Adoption Tables as they are not within the State Fire Marshal’s authority to adopt. These provisions are a reprint from the current CCR, Title 14, Division 1.5 text for the code user’s convenience only and are identified in the body of the code by square brackets containing references to applicable Title 14 sections.
2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 1-1
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
1-2 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
1 ADMINISTRATION
DIVISION I
CALIFORNIA ADMINISTRATION
SECTION 1.1—GENERAL
1.1.1 Title. These regulations shall be known as the California Wildland-Urban Interface Code, may be cited as such, and will be referred to herein as “this code.” The California Wildland-Urban Interface Code is Part 7 of thirteen parts of the official compilation and publica- tion of the adoptions, amendment, and repeal of building regulations to the California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This part incorporates by adoption of the 2024 International Wildland-Urban Interface Code of the International Code Council (ICC) with necessary California amendments.
_**1.1.2 Purpose.
Frequently asked questions
What test report do I need to show a material is noncombustible?
You need a test report showing the material passed ASTM E136, or an ASTM E2652 report that was evaluated using the acceptance criteria prescribed by ASTM E136, as required by § 501.4.1.
Can I use interior‑rated fire‑retardant wood outdoors if it was treated?
No. Fire‑retardant‑treated wood must be identified for exterior use and meet the CBC requirements referenced in § 503.2.2; interior‑only FRT products do not satisfy the CWUIC exterior requirement.
Is a thin metal‑faced panel always acceptable without testing?
Not always. The CWUIC includes specific exceptions for certain metal facings and for thin surfacings over noncombustible bases (for example surfacing ≤ 0.125 inch and flame spread ≤ 50), but you must confirm the exact exception language and thickness or metal gauge in the applicable code paragraphs before applying the exception. § 501.4 contains the surfacing exception language.
If a material passes ASTM E84 with a low flame spread, is it noncombustible?
No — ASTM E84 (flame spread) is not the primary test for “noncombustible.” ASTM E136 (or E2652 with E136 acceptance criteria) is required to classify a material as noncombustible per § 501.4.1. ASTM E84 results are used in specific exceptions or for other ignition‑resistant categories in Chapter 5.
Where do I find the technical acceptance criteria for exterior FRT wood?
The CWUIC requires compliance with CBC Section 2303.2 for exterior fire‑retardant‑treated wood per § 503.2.2; the technical acceptance criteria are in the California Building Code (CBC § 2303.2), which you should consult directly.
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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