WILDLAND URBAN INTERFACE (WUI)
CODES AND STANDARDS

The 2007 California Building Code (CBC) Chapter 7A, effective January 1, 2008, amended the previous standards associated with the construction of structures in wildfires prone areas. The prior standards were known as the Urban Wildland Intermix Code (UWIC). These Frequently Asked Questions and typical details address many concerns raised by the new WUI standards. The actual code standards should also be reviewed prior to the implementation of any design or construction project in state and local fire-hazard areas. Web resources are also identified for assistance in better understanding the standards and for identification of approved methods and materials that are allowed.

FREQUENTLY ASKED QUESTIONS

1. How do I determine if my construction project is subject to WUI requirements

Computer-accessed maps of the fire-hazard severity zones known as State Responsibility Areas (SRA) and the Local Responsibility Areas (LRA) are available at the Zoning counter in the Planning Department. Counter technicians can assist in determining if your project is within the SRA or LRA Zones. These maps are also available through the internet at www.sccoplanning.com .  Select the Mapping & GIS link then the GIS WEB Interactive Mapping Application. Enter your Assessors Parcel Number in the ‘value’ box. Enlarge the Parcel (Assessors) box – the SRA/LRA information is at the bottom of the list.    

Note: The Assessors Parcel Number (APN) of the project will be necessary to locate the relevant information. 

The WUI standards apply only to new buildings of all occupancy types. Existing permitted buildings, additions, and alterations are exempt.

Ancillary (detached accessory) buildings and structures. CBC 704A.5 & Santa Cruz County Code12.10.215(e)

Detached non -habitable accessory buildings such as garages or storage sheds that are under 500 square feet and more than 20 feet from other structures or detached nonhabitable accessory buildings greater than 500 square feet that are at least 30 feet from other structures, are exempt.          

Review all applicable requirements of CBC Chapter 7A with your architect, engineer or design professional. Plan reviewers and the Supervising Building Inspector are available to answer technical questions.  These code requirements are uniform California standards developed by

the Office of the State Fire Marshal. Additional information of approved materials, SRA maps and informational publications are available at the following web sites: osfm.fire.ca.gov & frap.cdf.ca.gov. 

The basic requirement is that the exterior of the structure be ignition-resistant and be able to resist the entry of flying embers and fire radiation during a wildfire. (See the WUI – Typical Details brochure) Various building components addressed in WUI are:

Roofs and roof edges.   CBC 704A.1.1, 1505.1

A noncombustible (tile or metal) or Class ‘A’ roofing assemblies areas is  required in SRA or LRA -  Very High Fire Hazard Severity Zones. Class ‘B’ roofing assemblies are required in all other areas of Santa Cruz County.
Where the roof profile allows a space between the roof covering and the roof decking, the spaces shall: be constructed to prevent the intrusion of flames and embers; be firestopped with approved materials; or have one layer of No. 72 cap sheet installed over the combustible decking.
Where provided, valley flashing must be not less than 26 gauge galvanized sheet metal over a 36-inch wide No. 72 ASTM cap sheet.

Roof eave construction and attic vents/roof vents.  CBC 704A.2.2 & 3

No vents are allowed in eaves or cornices. Eaves and soffits must be ignition-resistant or noncombustible.

Exterior Walls/siding.  CBC 704A.3

Noncombustible (no metal or vinyl siding unless approved), listed ignition- resistant materials, heavy timber, or log wall construction allowed.     
Exterior wall vents openings must resist the intrusion of flame and embers or must be ¼ inch corrosion-resistant, noncombustible wire mesh or equivalent.   

Windows and exterior doors.  CBC 704A .3.2.2

Windows must be insulated glass with a minimum of 1 tempered pane or glass block.
Exterior doors must be noncombustible, or 1 3/8” solid core, or have a 20 min fire-resistance rating.
Vehicle Access Doors that are noncombustible or exterior fire-retardant treated wood are allowed.

Decking, surfaces, stairs treads, risers and landings. CBC 704A.4.1

Decks, porches and balconies surfaces within 10 feet of the primary structure must be constructed of noncombustible, fire-retardant treated or heavy-timber construction. Alternate materials can be used of they are ignition-resistant and pass performance requirements specified by the State Fire Marshal.         

Underfloor protection.  CBC 704A.4.2

The underside of cantilevered and overhanging decks, balconies and similar appendages must maintain the same ignition-resistance of exterior walls or be enclosed to grade.          

Note: Ignition-resistant materials are those tested by a facility recognized by the State Fire Marshal or ICC-Evaluation Service to have a flame-spread rating not over 25, and comply with accelerated weathering tests. CBC 702A 

The building permit application and plans must identify whether the new structure is in an SRA or LRA zone and provide sufficient detail to determine compliance with WUI standards. 

The building inspector will perform the regular inspections associated with construction of a new structure. Upon completion of construction, the owner will receive certification that the building complies with WUI standards in the form of a finaled Building Permit that will include compliance with vegetation clearance requirements as enforced by the local Fire Agency having jurisdiction. CBC 704A.3.2.3 & 4