CWUIC · California Wildland-Urban Interface Code

What defensible‑space features and maintenance are recommended?

Q: Is Appendix G mandatory?

No. Appendix G (including § G101.3 and § G101.3.1 ) is informational and intended as voluntary best‑practice guidance for home hardening; it is not itself a mandatory construction regulation.

Q: Where is “defensible space” officially defined?

The CWUIC defines DEFENSIBLE SPACE in § 601.3 .

Appendix G of the CWUIC gives homeowners voluntary, practical defensible‑space and maintenance recommendations (clean roofs/gutters, remove combustibles within 5 ft of decks/windows/doors, clear branches 10 ft from chimneys, store firewood 30 ft away, seal gaps >1/8 in, use ember‑resistant products) to reduce wildfire ignition risk; “defensible space” is defined in § 601.3 and Chapter 6 contains the mandatory vegetation maintenance references in certain areas.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The CWUIC frames DEFENSIBLE SPACE as the required buffer between a building or structure and surrounding vegetation or materials that could ignite; the definition is in § 601.3. The Appendix G recommendations in § G101.3 and the detailed maintenance items listed in § G101.3.1 are presented as voluntary, best‑practice home‑hardening and maintenance guidance to increase a home’s survivability in a wildfire. These recommendations (roof, gutters, decks, chimneys, openings, storage, and separations) are intended as homeowner actions, not prescriptive mandatory construction requirements; see § G101.3 and § G101.3.1 for the list.

Defensible space is the buffer a landowner must create between structures and nearby vegetation or items that could ignite; it reduces the chance that external wildfire will ignite the structure. § 601.3

Requirements in detail

Primary concept (definition)

DEFENSIBLE SPACE — the buffer between a building or structure and surrounding plants, brush, trees, or other items that could ignite and spread fire to the structure (§ 601.3).

Key recommended features and maintenance (summary)

Keep roofs and roof‑to‑wall intersections clear of leaves, needles and other flammable debris; repair damaged roofing and remove overhanging vegetation. § G101.3.1.
Keep rain gutters free of combustible debris; consider noncombustible gutters and covers. § G101.3.1.
Decks and balconies: clean deck surfaces and intersections, remove combustibles from beneath and within 5 feet (1524 mm) of a deck or balcony. § G101.3.1.
Chimneys/stovepipes: keep spark arrestor in place and remove branches within 10 feet. § G101.3.1.
Windows and doors: remove combustibles within 5 feet (1524 mm); replace older windows with multipane/tempered glazing when due. § G101.3.1.
Sealing & openings: caulk/plug gaps greater than 1/8 inch (3.2 mm); weather‑strip garage doors to prevent ember intrusion and select compliant materials. § G101.3.1.
Under‑deck and deck‑to‑wall protection: install minimum 6‑inch metal flashing at the deck‑to‑wall intersection; enclose openings beneath decks using ignition‑resistant or specified mesh (see § G101.3.1).
Firewood & combustible storage: store exposed firewood at least 30 feet (9144 mm) from structures or fully cover with a fire‑resistant enclosure that blocks embers. § G101.3.1.

Decision table — quick numeric/threshold reference

Feature / Issue	Recommended action	Key dimension / threshold	Code Reference
Defensible space (definition)	Create buffer between building and vegetation	—	§ 601.3
Decks / balconies	Remove combustibles on/under/within zone	5 ft (1524 mm)	§ G101.3.1
Windows / doors	Remove nearby combustibles; upgrade glazing	5 ft (1524 mm); upgrade to multipane/tempered when replacing	§ G101.3.1
Chimneys / stovepipes	Install/maintain spark arrestor; clear branches	Branches cleared within 10 ft; spark arrestor in place	§ G101.3.1
Gaps / openings	Seal gaps to prevent ember intrusion	Gaps > 1/8 in (3.2 mm) must be caulked/plugged; mesh openings limits noted	§ G101.3.1
Skylights / vents	Cover with noncombustible mesh / ember‑resistant products	Skylight/vent mesh opening ≤ 1/8 in (3.2 mm) (temporary)	§ G101.3.1
Deck‑to‑wall intersection	Protect siding and junction	6‑inch metal flashing minimum	§ G101.3.1
Firewood storage	Distance or fully enclosed cover	30 ft (9144 mm) or fully covered by fire‑resistant enclosure	§ G101.3.1
Outbuildings (clearance)	Maintain cleared area to mineral soil	10 ft (3048 mm) to bare mineral soil; vegetation 10–20 ft must be fire‑smart	§ 604.4

Notes: Appendix G is informational and its items are presented as best‑practice suggestions (voluntary retrofit/home‑hardening measures) — see § G101.3 and § G101.3.1.

Materials & product recommendations

Choose noncombustible, ignition‑resistant, or OSFM‑approved WUI products for vents, siding, gutters, decking and replacement materials when these components are due for replacement (§ G101.3.1).
Where temporary solutions are used (e.g., covering vents), use corrosion‑resistant, noncombustible meshes within the opening size limits shown in § G101.3.1.

Exceptions & special cases

Appendix G is expressly informational — its recommendations are presented as voluntary home‑hardening guidance, not mandatory code requirements; see § G101.3. If you need a mandatory defensible‑space requirement, consult the maintenance provisions and state laws cited in § 604.3 (PRC 4291 and related regulations).
Outbuildings have a specific, mandatory clearance requirement in Chapter 6: 10 feet to bare mineral soil; vegetation 10–20 feet from outbuildings must be fire‑smart (§ 604.4). This is distinct from voluntary Appendix G guidance.
Some product or construction specifics (e.g., exact WUI product listings, UL/OSFM labeling) are referenced but require consulting the product standard or OSFM lists; Appendix G points you to using OSFM‑approved WUI products for vents and glazing (§ G101.3.1).

Common mistakes

Treating Appendix G items as mandatory code rather than voluntary guidance — Appendix G is informational; § G101.3 clarifies intent.
Ignoring the small but critical thresholds: e.g., failing to seal gaps > 1/8 inch (3.2 mm) (ember intrusion risk) or to clear 5 ft around decks/windows. These exact thresholds appear in § G101.3.1 and are practical triggers for action.
Assuming “clearance” always means the same distance for every element — outbuildings, decks, windows, chimneys and firewood each have different recommended distances in the code appendices and Chapter 6; check the specific § for each item (for example, § G101.3.1 vs. § 604.4).
Using combustible storage under elevated decks or within 5 feet of decking — Appendix G explicitly recommends removing combustibles from underneath and within 5 ft of decks. § G101.3.1.

Worked example — single‑family home on a wooded lot

Scenario: Single‑family home with a wooden deck, woodpile near the garage, and a chimney with nearby tree branches.

Step 1 — Decks & nearby combustibles

Action: Remove all firewood, propane cylinders and stored combustibles from under the deck and from within 5 ft (1524 mm) of the deck perimeter. This follows the Appendix G deck guidance in § G101.3.1.

Step 2 — Chimney clearance & spark arrestor

Action: Confirm a spark arrestor is installed and clean; prune tree limbs so no branches come within 10 ft of the chimney outlet. This aligns with § G101.3.1.

Step 3 — Firewood storage

Action: Move the woodpile to at least 30 ft (9144 mm) from the house or store it in a fire‑resistant enclosure that blocks ember penetration. This directly follows § G101.3.1.

Step 4 — Gaps and openings

Action: Inspect exterior siding, eaves and garage door edges; caulk or plug any gaps larger than 1/8 in (3.2 mm) and install weatherstripping at garage doors compliant with relevant standards if necessary. This follows § G101.3.1.

Step 5 — Roof & gutters

Action: Clean roof and gutters of needles and leaves (including roof‑to‑wall intersections and around skylights) and repair damaged roofing materials to reduce ember accumulation; consider gutter covers or noncombustible gutters. § G101.3.1.

After these steps the homeowner will have implemented the primary Appendix G defensible‑space recommendations relevant to the scenario (deck clearance, chimney, firewood, gaps, roof/gutters) as described in § G101.3.1.

Related provisions

§ G101.3 — Defensible‑space features (Appendix G guidance and intent).
§ G101.3.1 — Maintenance and defensible‑space operational procedures (detailed recommendations listed).
§ 601.3 — Definition of DEFENSIBLE SPACE (Chapter 6 definitions).
§ 604.4 — Outbuilding clearance and vegetation requirements (minimum 10 ft to bare mineral soil).
§ 604.3 — Reference to mandatory maintenance laws and regulations (PRC 4291 and others) for hazardous vegetation around buildings.
For product standards and additional construction measures referenced by Appendix G (vents, WUI product lists, flashing sizes), see the specific Appendix G items in § G101.2.1 and § G101.3.1.

Code references

Grounded in the retrieved California Wildland-Urban Interface Code — click a citation to read the verbatim passage:

CWUIC § 3.1 High relevance — show source text
Detached fences that are located within 5_ feet (1524 mm) of the structure should be replaced with noncombustible or ignition-resistant building materials.

G101.3 Defensible space features. The maintenance and defensible space features listed in Section G101.3.1 were developed as a best practices guide to assist homeowners to increase the effectiveness of their defensible space and improve the effects of the home-harden- ing features to increase the survivability of their homes from wildfires.

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APPENDIX G—VOLUNTARY HOME-HARDENING RECOMMENDATIONS

G101.3.1 Maintenance and defensible space. The following maintenance and operational procedures assist to limit the impact on a home from an approaching wildfire. 1. Roofs—regularly clean your roof, including roof-to-wall intersections and skylights to remove accumulated fallen leaves, needles and other flammable materials; repair damaged or deteriorated sections of the roof or roof covering; remove all trees, branches, shrubs or other plants adjacent to or overhanging buildings. 2. Rain gutters—keep roof gutters free of combustible debris. 3. Decks—regularly clean your deck, including deck-to-wall intersections to avoid the accumulation of fallen leaves, needles and other flammable materials; ensure that all combustible materials are removed from underneath, on top of or within five feet (1524 mm) of a deck or balcony. 4. Chimneys—ensure spark arrestor is in place; remove all branches within 10 feet of any chimney or stovepipe outlet. 5. Windows—remove or relocate all combustibles away from windows. Older windows that are single-pane or double-pane without tempering can be vulnerable to direct flame contact or radiant heat exposure; remove vegetation or other combus- tible materials that are within five feet of windows.

6. Doors—inspect the door for dry rot, gaps, cracks and warping and caulk or plug gaps greater than [1] / 8 inch. Install weather stripping to fill gaps greater than [1] / 8 inch (3.2 mm) between garage doors and door frames to prevent ember intrusion; remove vegetation or other combustible materials that are within five feet (1524 mm) of doors. 7. Exterior walls—inspect exterior siding for dry rot, gaps, cracks and warping and caulk or plug gaps greater than [1] / 8 inch in siding and replace any damaged boards, including those with dry rot. 8. Firewood—exposed firewood is stored at least 30 feet (9144 mm) away from structures or completely covered in a fire-resis- _tant material that will not allow embers to penetrate.
CWUIC § 3.2 High relevance — show source text
Caulk or plug gaps greater than_ [1] / 8 inch (3.2 mm) in siding and replace any damaged boards, including those with dry rot. 8. Install weather stripping to fill gaps greater than [1] / 8 inch (3.2 mm) between garage doors and door frames to prevent ember intrusion. The weather stripping must be compliant with UL Standard 10C. 9. When it’s time to replace your windows, replace them with multipaned windows that have at least one pane of tempered glass. Choose products that have been approved and labeled as OSFM Wildland-Urban Interface (WUI) Products. 10. When it’s time to replace your siding or deck, use noncombustible, ignition-resistant, or other OSFM-approved Wildland- Urban Interface (WUI) Products. 11. Cover openings to operable skylights with noncombustible metal mesh screen with openings in the screen not to exceed [1] / 8 inch (3.2 mm). 12. Install a minimum 6-inch metal flashing, applied vertically on the exterior of the wall at the deck-to-wall intersection to protect the combustible siding material. 13. Enclose openings beneath decks or cantilevered construction with one of the materials required in Section 504.5. Openings beneath decks which are four feet (1219 mm) or less above grade can be covered with a noncombustible and corrosion- resistant mesh with [1] / 16 -inch (1.6 mm) to [1] / 8 -inch (3.2 mm) openings. 14. Remove or replace combustible fences within 5 feet (1524 mm) of the structure. Detached fences that are located within 5 feet (1524 mm) of the structure should be replaced with noncombustible or ignition-resistant building materials.

G101.3 Defensible space features. The maintenance and defensible space features listed in Section G101.3.1 were developed as a best practices guide to assist homeowners to increase the effectiveness of their defensible space and improve the effects of the home-harden- ing features to increase the survivability of their homes from wildfires.

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APPENDIX G—VOLUNTARY HOME-HARDENING RECOMMENDATIONS

G101.3.1 Maintenance and defensible space. The following maintenance and operational procedures assist to limit the impact on a home from an approaching wildfire. 1. Roofs—regularly clean your roof, including roof-to-wall intersections and skylights to remove accumulated fallen leaves, needles and other flammable materials; repair damaged or deteriorated sections of the roof or roof covering; remove all trees, branches, shrubs or other plants adjacent to or overhanging buildings. 2. Rain gutters—keep roof gutters free of combustible debris. 3. Decks—regularly clean your deck, including deck-to-wall intersections to avoid the accumulation of fallen leaves, needles and other flammable materials; ensure that all combustible materials are removed from underneath, on top of or within five feet (1524 mm) of a deck or balcony. _4.
CWUIC § 6-4 High relevance — show source text
structure.

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FIRE PROTECTION REQUIREMENTS

SECTION 604—MAINTENANCE OF DEFENSIBLE SPACE

604.1 General. Hazardous vegetation and fuels shall be managed to reduce the severity of potential exterior wildfire exposure to build- ings and to reduce the risk of fire spreading to buildings as required by applicable laws and regulations.

Defensible space shall be managed around all buildings and structures in State Responsibility Areas (SRA) as required in Public Resources Code 4291.

604.2 Application. Buildings and structures located in the following areas shall maintain the required hazardous vegetation and fuel management: 1. All unincorporated lands designated as a State Responsibility Area (SRA). 2. Land designated as a Very High Fire Hazard Severity Zone by a city or local agency. 3. Land designated in a city or local agency ordinance as a wildland-urban interface (WUI) area.

604.3 Requirements. Hazardous vegetation and fuels around all buildings and structures shall be maintained in accordance with the following laws and regulations: 1. Public Resources Code, Section 4291.

2. California Code of Regulations, Title 14, Division 1.5, Chapter 7, Subchapter 3, Article 3, Section 1299.03. 3. California Government Code, Section 51182.

4. California Code of Regulations, Title 19, Division 1, Chapter 7, Subchapter 1, Section 3.07.

604.4 Outbuildings. Outbuildings shall have a minimum clearance of 10 feet (3048 mm) down to bare mineral soil in all directions. Vege- tation more than 10 feet (3048 mm) but less than 20 feet (6096 mm) from outbuildings shall be fire-smart vegetation.

604.5 Disposal of flammable vegetation and fuels. The disposal, including burning or removal to a site approved by the local jurisdic- tion in consultation with the fire authority, of flammable vegetation and fuels caused by site, road and driveway construction shall be in accordance with all applicable laws and regulations. [CCR T14 §1276.05]

SECTION 605—SPARK ARRESTORS

605.1 General. Chimneys serving fireplaces, barbecues, incinerators or decorative heating appliances in which solid or liquid fuel is used shall be provided with a spark arrestor. Spark arrestors shall be constructed of woven or welded wire screening of 12 USA standard gage wire (0.1046 inch) (2.66 mm) having openings not exceeding [1] / 2 inch (12.7 mm).

605.2 Net free area. The net free area of the spark arrestor shall be not less than four times the net free area of the outlet of the chimney.

SECTION 606—LIQUEFIED PETROLEUM GAS INSTALLATIONS

606.1 General. The storage of liquefied petroleum gas (LP-gas) and the installation and maintenance of pertinent equipment shall be in accordance with the California Fire Code .

606.2 Location of containers or tanks. LP-gas containers or tanks shall be located within the defensible space in accordance with the California Fire Code .
CWUIC § 6-1 High relevance — show source text
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6 FIRE PROTECTION REQUIREMENTS

User notes:

About this chapter: In addition to the building construction requirements in the California Building Code and California Residential Code, this chapter contains requirements for development and construction in Local Responsibility Areas (LRA) designated as Very High Fire Hazard Severity Zones and areas designated by the State Fire Marshal as State Responsibility Areas (SRA). While many of these provisions are found in Title 14 and Title 19 of the California Code of Regulations, they are replicated here for the code user. The local jurisdiction has the authority to apply the same regulations to LRA when the regulations are adopted by local ordinance.

The requirements in this chapter reference the process for adoption of Very High Fire Hazard Severity Zones in the LRA; criteria for evaluating existing subdivisions that are at significant fire risk and are without an adequate secondary egress; and criteria for fire safety provisions required in the Safety Element of a city or county General Plan.

The chapter includes mitigation strategies to reduce the hazards of fire originating within a structure spreading to wildland and fire originating in wildland spreading to structures. These strategies are included in the following requirements:

1. Development of fire protection plans.

2. Development of landscape plans and long-term vegetation management.

3. Creation and maintenance of defensible space to protect structures and subdivisions.

SECTION 601—GENERAL

601.1 Scope. The provisions of this chapter establish general requirements for new and existing buildings, structures and premises located within wildland-urban interface (WUI) areas .

601.2 Objective. The objective of this chapter is to establish minimum requirements to mitigate conditions that might cause a fire originating in a structure to ignite vegetation in the wildland-urban interface (WUI) area, and conversely, a wildfire burning in vegetative fuels to transmit fire to buildings and threaten to destroy life, overwhelm fire suppression capabilities or result in large property losses.

601.3 Chapter 6 definitions. Where used in this chapter, the term listed below shall be defined as follows:

DEFENSIBLE SPACE. The buffer that landowners are required to create on their property between a “Building or Structure” and the plants, brush and trees or other items surrounding the “Building or Structure” that could ignite in the event of a fire. [CCR Title 14 §1299.02(a)]

SECTION 602— FIRE PROTECTION PLANS

602.1 General. The code official is authorized to require the owner or owner’s authorized agent to provide a fire protection plan. The fire protection plan shall be prepared to determine the acceptability of fire protection and life safety measures designed to mitigate wildfire hazards presented for the property under consideration.

The fire protection plan shall be prepared by a registered design professional, qualified landscape architect, qualified fire safety specialist or similar specialist acceptable to the code official and shall analyze the wildfire risk of the building, project, premises or region to recommend necessary changes.

The code official is authorized to require a preliminary fire protection plan prior to the submission of a final fire protection plan.
CWUIC § 601.1 High relevance — show source text
SECTION 601—GENERAL

601.1 Scope. The provisions of this chapter establish general requirements for new and existing buildings, structures and premises located within wildland-urban interface (WUI) areas .

601.2 Objective. The objective of this chapter is to establish minimum requirements to mitigate conditions that might cause a fire originating in a structure to ignite vegetation in the wildland-urban interface (WUI) area, and conversely, a wildfire burning in vegetative fuels to transmit fire to buildings and threaten to destroy life, overwhelm fire suppression capabilities or result in large property losses.

601.3 Chapter 6 definitions. Where used in this chapter, the term listed below shall be defined as follows:

DEFENSIBLE SPACE. The buffer that landowners are required to create on their property between a “Building or Structure” and the plants, brush and trees or other items surrounding the “Building or Structure” that could ignite in the event of a fire. [CCR Title 14 §1299.02(a)]

SECTION 602— FIRE PROTECTION PLANS

602.1 General. The code official is authorized to require the owner or owner’s authorized agent to provide a fire protection plan. The fire protection plan shall be prepared to determine the acceptability of fire protection and life safety measures designed to mitigate wildfire hazards presented for the property under consideration.

The fire protection plan shall be prepared by a registered design professional, qualified landscape architect, qualified fire safety specialist or similar specialist acceptable to the code official and shall analyze the wildfire risk of the building, project, premises or region to recommend necessary changes.

The code official is authorized to require a preliminary fire protection plan prior to the submission of a final fire protection plan.

602.2 Contents. The fire protection plan shall be based on a project-specific wildfire hazard assessment that includes considerations of location, topography, aspect and climatic and fire history.

The plan shall identify conformance with all applicable state wildfire protection regulations, statutes and applicable local ordi- nances, whichever are more restrictive.

The plan shall address fire department access, egress, road and address signage and water supply in addition to fuel reduction in accordance with Public Resources Code (PRC) 4290; the defensible space requirements in accordance with PRC 4291 or Government Code 51182; and the applicable building codes and standards for wildfire safety. The plan shall identify mitigation measures to address the project’s specific wildfire risk and shall include the information required in Sections 602.3 through 602.3.2.

602.3 Project information. The final fire protection plan shall be reviewed and approved prior to start of construction.

602.3.1 Preliminary fire protection plan. When a preliminary fire protection plan is submitted, it shall include, at a minimum, the following: 1. Total size of the project. 2. Information on the adjoining properties on all sides, including current land uses, and if known, existing structures and densi- ties, planned construction, natural vegetation, environmental restoration plans, roads and parks. 3. A map with all project boundary lines, property lines, slope contour lines, proposed structure foundation footprints, and proposed roads and driveways. The map shall identify project fuel modification zones and method of identifying the fuel modification zone boundaries.

2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 6-3
CWUIC § 5-3 High relevance — show source text
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

605 Spark Arrestors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

606 Liquefied Petroleum Gas Installations . . . . . . . . . . . 6-5

607 Storage of Firewood and Combustible Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

608 Building Siting and Setbacks . . . . . . . . . . . . . . . . . . . . 6-5

609 Ridgelines, Fuel Breaks and Greenbelts . . . . . . . . . . . 6-6

610 Fire Safe Development Regulations . . . . . . . . . . . . . . 6-7

611 Subdivision Review Survey . . . . . . . . . . . . . . . . . . . . . . 6-7

612 General Plan Safety Element . . . . . . . . . . . . . . . . . . . . 6-7

CHAPTER 7 REFERENCED STANDARDS . . . . . . . . . . . . . .7-3

APPENDIX A GENERAL REQUIREMENTS . . . . APPENDIX A-3

A101 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX A-3

A102 Vegetation Control. . . . . . . . . . . . . . . . . . . APPENDIX A-3
CWUIC § 609.2.3 High relevance — show source text
609.2.3 Location of fuel breaks. Fuel breaks may be required at locations such as, but not limited to: (1) Directly adjacent to defensible space as defined by Title 14 CCR Section 1299.02 to reduce radiant and convective heat expo- sure and ember impacts, or support firefighting tactics. (2) Directly adjacent to roads to manage radiant and convective heat exposure and ember impacts, increase evacuation safety, or support firefighting tactics. (3) Directly adjacent to a hazardous land use to limit the spread of fire from such uses, reduce radiant and convective heat exposure, or support firefighting tactics. (4) Strategically located along ridgelines, in greenbelts, or in other locations to reduce radiant and convective heat exposure and ember impacts, or support community level firefighting tactics.

[CCR T14 §1276.03(d)]

609.2.4 Timing. Fuel breaks shall be completed prior to the commencement of any permitted construction. [CCR T14 §1276.03(e)]

609.2.5 Construction. Fuel breaks shall be constructed using the most ecologically and site appropriate treatment option, such as, but not limited to, prescribed burning, manual treatment, mechanical treatment, prescribed herbivory, and targeted ground applica- tion of herbicides. [CCR T14 §1276.03(f)]

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FIRE PROTECTION REQUIREMENTS

609.2.6 Maintenance of fuel breaks. Where a local jurisdiction requires fuel breaks, maintenance mechanisms shall be established to ensure the fire behavior objectives and thresholds are maintained over time.

The mechanisms required shall be binding upon the property for which the fuel break is established, shall ensure adequate main- tenance levels, and may include: written legal agreements; permanent fees, taxes, or assessments; assessments through a homeowners’ association; or other funding mechanisms. [CCR T14 §1276.03(g) and (h)]

609.2.7 Greenbelts, greenways, open spaces and parks. Where a greenbelt, greenway, open space, park, landscaped or natural area or portion thereof is intended to serve as a fuel break, the space or relevant portion thereof shall conform with the requirements in California Code of Regulations, Title 14, Section 1276.03. [CCR T14 §1276.04]

SECTION 610—FIRE SAFE DEVELOPMENT REGULATIONS

610.1 General. Pursuant to Public Resources Code, Section 4290, all residential, commercial and industrial building construction within state responsibility areas approved after January 1, 1991, and within lands classified and designated as an LRA Very High Fire Hazard Severity Zone, as defined in subdivision (i) of Section 51177 of the Government Code after July 1, 2021, shall comply with the SRA Fire Safe Development Regulations as specified in Title 14, Division 1.5, Chapter 7, Subchapter 2.

CWUIC § 3.2.2 High relevance — show source text

3.2.2|Minimum clearance
to be maintained|N|||||||4293
4296|| |A102.3.2.3|Electrical power line
emergencies|N||||||||| |A102.4|Correction of
condition|N||||||||| |A103|Access restrictions|N||||||||| |A103.1|Restricted entry to
public lands|N||||||||| |A103.2|Trespassing on
posted private
property|N||||||||| |A103.2.1|Signs|N||||||||| |A103.2.2|Trespassing|N||||||||| |A103.3|Use of fire roads and
defensible space|N||||||||| |A103.3.1|Obstructions|N||||||||| |A103.4|Use of motorcycles,
motor scooters, ultra-
light aircraft and
motor vehicles|N||||||||| |A103.5|Tampering with
locks, barricades,
signs and address
markers|N|||||||||

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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, Division 1 Section	Gov Code Section	PRC Section	HSC Section
Section	Title	Title	Title	Title	Title	Title	Title	Title	Title	Title
Appendix A	General requirements	General requirements	General requirements	General requirements	General requirements	General requirements	General requirements	General requirements	General requirements	General requirements
A103.5.1	Gates, doors, barriers and locks	N
A104	Ignition source control	N
A104.1	General	N
A104.2	Objective	N
A104.3	Clearance from igni- tion sources	N
A104.4	Smoking	N
A104.5	Equipment and devices generating heat, sparks or open flames	N
A104.6	Fireworks	N
A104.6.1	Authority to seize	N
A104.7	Outdoor fires	N
A104.7.1	General	N
A104.7.2	Permits	N
A104.7.3	Restrictions	N
A104.8	Incinerators, outdoor fireplaces, perma- nent barbecues and grills	N
A104.8.1	Maintenance	N
A104.

CWUIC § 404.9 High relevance — show source text
May_ 1988.

404.9 Testing and maintenance. Water sources, draft sites, hydrants and other fire protection equipment required by this code shall be subject to periodic tests as required by the code official. Such equipment installed under the provisions of this code shall be maintained in an operative condition at all times and shall be repaired or replaced where defective. Additions, repairs, alterations and servicing of such fire protection equipment and resources shall be in accordance with approved standards.

404.10 Reliability. Water supply reliability shall comply with Sections 404.10.1 through 404.10.3.

404.10.1 Objective. The objective of this section is to increase the reliability of water supplies by reducing the exposure of vegetative fuels to electrically powered systems.

404.10.2 Clearance of fuel. Defensible space shall be provided around water tank structures, water supply pumps and pump houses in accordance with Section 603.

2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE 4-7

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

WILDLAND-URBAN INTERFACE AREA REQUIREMENTS

404.10.3 Standby power. Standby power shall be provided to pumps, controllers and related electrical equipment so that stationary water supply facilities within the wildland-urban interface area that are dependent on electrical power can provide the required water supply. The standby power system shall be in accordance with Section 2702 of the California Building Code and Section 1203 of the California Fire Code . The standby power source shall be capable of providing power for not less than 2 hours.

Exceptions:
1. Where approved by the code official, a standby power supply is not required where the primary power service to the stationary water supply facility is underground.
2. A standby power supply is not required where the stationary water supply facility serves not more than one singlefamily dwelling.
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4-8 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE

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CALIFORNIA WILDLAND-URBAN INTERFACE CODE – MATRIX ADOPTION TABLE

CHAPTER 5 – SPECIAL BUILDING CONSTRUCTION REGULATIONS

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CWUIC § 3-3 High 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 § 2.1 High relevance — show source text
This appendix is for informational purposes and is not intended for adoption.

User notes:

About this appendix: Appendix G is an information appendix that provides discussion of some elements of the proposed self-defense mechanisms and their role in enhancing the protection of exposed structures in the wildland-urban interface. The items provided in this appendix provide owners with suggestions for increasing the survivability of their structure. These items are not mandatory but can be considered by owners to increase the safety of structures.

SECTION G101—GENERAL

G101.1 Identification of the problem. The California Wildland-Urban Interface Code establishes a set of minimum standards to reduce the loss of property from wildfire. The purpose of these standards is to prevent wildfire spreading from vegetation to a building. Many homes were built in the wildland-urban interface areas prior to the implementation of provisions found in this code. As a result, many homes are lacking in their ability to survive an approaching wildfire. Many of the features discussed in this appendix are designed as low- cost features to retrofit existing homes. Additionally, recommendations are provided beyond the minimum code requirements for those homeowners who desire to increase the survivability of their home. This appendix chapter provides a discussion of some possible self- defense features to enhance survivability and harden the structure against an approaching wildfire.

G101.2 Structural survivability. The home-hardening features listed in Section G101.2.1 were developed as a best practices guide to assist homeowners in increasing the ignition resistance of their homes from wildfires. Some of these items are based on upgrading to more stringent building materials when that building component is due for replacement as part of its normal maintenance or lifespan, such as the roof covering.

G101.2.1 Home-hardening features. If homes are not already provided with the suggested protection, the following items should be considered in hardening a home against wildfire. 1. When it is time to replace your roof, replace it with roof assembly classified as Class A when tested in accordance with ASTM E108 or UL 790.

2. Block any spaces at the eaves between your roof covering and sheathing with noncombustible materials (bird stops). 3. Install a noncombustible rain gutter and downspouts. Install rain gutter covers to prevent the accumulation of leaves and debris in the gutters. 4. Cover your chimney and stovepipe outlets with a noncombustible, corrosion-resistant metal mesh screen (spark arrestor), with [3] / 8 -inch (9.5 mm) to [1] / 2 -inch (12.7 mm) openings. 5. Install ember- and flame-resistant vents. Choose products that have been approved and labeled as OSFM Wildland-Urban Interface (WUI) Products. A temporary solution is to cover the vent openings with a noncombustible and corrosion-resistant mesh with [1] / 16 -inch (1.6 mm) to [1] / 8 -inch (3.2 mm) openings. 6. Caulk and plug gaps greater than [1] / 8 inch (3.2 mm) around exposed rafters and blocking to prevent ember intrusion into the attic or other enclosed spaces. 7. _Inspect exterior siding for dry rot, gaps, cracks and warping.
CWUIC § 4.1 High relevance — show source text
2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE APPENDIX A-5

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX A—GENERAL REQUIREMENTS

A105.3 Explosives. Explosives shall not be possessed, kept, stored, sold, offered for sale, given away, used, discharged, transported or disposed of within wildland-urban interface areas, except by permit from the code official.

A105.4 Combustible materials. Outside storage of combustible materials such as, but not limited to, wood, rubber tires, building materials or paper products shall comply with the other applicable sections of this code and this section. A105.4.1 Individual piles. Individual piles shall not exceed 5,000 square feet (465 m [2] ) of contiguous area. Piles shall not exceed 50,000 cubic feet (1416 m [3] ) in volume or 10 feet (3048 mm) in height.

A105.4.2 Separation. A clear space of not less than 40 feet (12 192 mm) shall be provided between piles. The clear space shall not contain combustible material or nonfire-smart vegetation.

SECTION A106—DUMPING

A106.1 Waste material. Waste material shall not be placed, deposited or dumped in wildland-urban interface areas or in, on or along trails, roadways or highways or against structures in wildland-urban interface areas .

Exception: Approved public and approved private dumping areas.

A106.2 Ashes and coals. Ashes and coals shall not be placed, deposited or dumped in or on wildland-urban interface areas.

Exceptions:
1. In the hearth of an established fire pit, camp stove or fireplace.
2. In a noncombustible container with a tightfitting lid, which is kept or maintained in a safe location not less than 10 feet (3048 mm) from nonfire-smart vegetation or structures.
3. Where such ashes or coals are buried and covered with 1 foot (305 mm) of mineral earth not less than 25 feet (7620 mm) from nonfire-smart vegetation or structures.
SECTION A107—PROTECTION OF PUMPS AND WATER STORAGE FACILITIES

A107.1 General. The reliability of the water supply shall be in accordance with Sections A107.2 through A107.5.

A107.2 Objective. The intent of this section is to increase the reliability of water storage and pumping facilities and to protect such systems against loss from intrusion by fire.

A107.3 Fuel modification area. Water storage and pumping facilities shall be provided with a defensible space of not less than 30 feet (9144 mm) clear of nonfire-resistive vegetation or growth around and adjacent to such facilities.

Persons owning, controlling, operating or maintaining water storage and pumping systems requiring this defensible space are responsible for clearing and removing nonfire-smart vegetation and maintaining the defensible space on the property owned, leased or controlled by said person.

A107.4 Trees. Portions of trees that extend to within 30 feet (9144 mm) of combustible portions of water storage and pumping facilities shall be removed.

Frequently asked questions

Is Appendix G mandatory?

No. Appendix G (including § G101.3 and § G101.3.1) is informational and intended as voluntary best‑practice guidance for home hardening; it is not itself a mandatory construction regulation.

Where is “defensible space” officially defined?

The CWUIC defines DEFENSIBLE SPACE in § 601.3.

Does the code set a single required distance for all vegetation clearance?

No. Appendix G recommends specific clearances for certain features (e.g., 5 ft for decks/windows, 10 ft for chimney clearance of branches, 30 ft for firewood storage), but Chapter 6 and referenced state laws (e.g., PRC 4291) set mandatory defensible‑space maintenance in some areas. See § G101.3.1 and § 604.3 for details.

What if I live in an SRA or a Very High Fire Hazard Severity Zone?

Owners in SRAs and locally designated WUI or VHFSZ areas must follow mandatory vegetation management and defensible‑space laws (see § 604.2 and § 604.3), in addition to considering Appendix G recommendations.

Where can I find approved WUI products for vents, windows or siding?

Appendix G recommends using OSFM‑approved WUI products; for the actual product listings and labeling requirements you must consult OSFM product lists and the product standard referenced in § G101.3.1.

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Related in the CWUIC

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Voluntary Home‑Hardening & Defensible Space (Appendix G)

California Wildland-Urban Interface Code