Section G101 — GENERAL

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.

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. 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.

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.

e 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. Additionally, make sure you have 10 feet (3048 mm) of clearance around your wood piles. 9. Fences—remove or relocate all vegetation, combustibles and combustible debris adjacent to and underneath fences. 10. Replace wood mulch products within five feet (1524 mm) of all structures with noncombustible products such as dirt, stone, or gravel. 11. Remove all dead or dying grass, plants, shrubs, trees, branches, leaves, weeds, and pine needles within 30 feet (9144 mm) of all structures or to the property line. 12. Be sure to store combustible outdoor furnishings away from your home when not in use. 13. Remember to properly store retractable awnings and umbrellas when not in use so they do not collect leaves and embers.

APPENDIX G-4 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE

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CALIFORNIA WILDLAND-URBAN INTERFACE CODE – MATRIX ADOPTION TABLE

APPENDIX H – REFERENCED CALIFORNIA DOCUMENTS

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

(Not adopted by the State Fire Marshal)

• 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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APPENDIX H-2 2025 CALIFORNIA WILDLAND-URBAN INTERFACE CODE

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