Wildland Urban Interface (WUI) Codes and Standards
Since 1980 California laws and codes have pursued mitigation strategies to reduce loss of life, property, and natural resources within the Fire Hazard Severity Zone (FHSZ). Additional information is provided by the Office of the State Fire Marshal (OSFM).
Which projects are subject to WUI requirements?
For parcels within the State Responsibility Area (SRA) of the County, WUI building requirements apply to all new structures, additions, and exterior alterations of existing structures regardless of use, size, separation distances, or occupancy type (including garages, workshops, greenhouses, etc.). It does not apply to parcels within the Local Responsibility Area (LRA).
How to determine if a parcel is within the SRA?
On the SCC GISWeb, search using the Accessors Parcel Number (APN) and then click "Hazards and GeoPhysical" at the bottom to view the “State Response Area”. For any SRA designation (moderate, high, very high), WUI conformance is required. An “LRA” designation is exempt. Permit technicians can assist with questions and GISWeb use.
Are there exceptions to WUI requirements?
The Santa Cruz County (SCC) amendments to the 2022 California Building Code (CBC) 701A.3 and California Residential Code (CRC) R337.1.3 scoping delete exceptions 1, 2, 4 and 5. The purpose of retaining exception 3 is to exempt tent structures used for sleeping purposes at public campgrounds. These amendments add the requirements noted above. SCC 12.10.215(D)/12.10.220(H)
The SCC amendments allow an exception for one of the following:
- Replacement of an area of wood siding not exceeding 100 sq. ft.
- Replacement of a broken window glass pane or glass door pane.
- Replacement of an area of roofing not exceeding 100 sq. ft.
- Replacement of one attic or foundation vent.
What WUI documentation is required for submittal review?
Note: The below is not all-inclusive, is subject to change, and does not substitute for code analysis or the services of a qualified design professional.
The below may assist with identifying basic code sections, approved product listings sources, and requirements to include in submittal documentation. Submittal documentation must clearly show code compliance by means specifications, details, assemblies, OSFM listings, OSFM handbook, and otherwise. WUI compliance requirements are in CBC 7A and CRC R337. Plan reviewers and the Supervising Building Inspector are available to answer technical questions.
- Product evaluation testing of material and material assemblies shall be approved or listed by the State Fire Marshal, or identified in a current report issued by an approved agency. CBC 703A.2/CRC R337.3.2
- Material and material assemblies tested in accordance with the requirements shall bear an identification label showing the fire test results. That identification label shall be issued by a testing and/or inspecting agency approved by the State Fire Marshal. CBC 703A.4/CRC R337.3.4
- The use of paints, coatings, stains or other surface treatments are not an approved method of protection. CBC 703A.5.3/CRC R3220.127.116.11
- Roof assembly Class A rating. CBC 705A.1/CRC R337.5.1
- Roof airspace under roof covering. CBC 705A.2/CRC R337.5.2
- Roof valley flashing. CBC 705A.3/CRC R337.5.3
- Roof gutters. CBC 705A.4/CRC R337.5.4
- Vents: Ventilation openings for enclosed attics, gable ends, ridge ends, under eaves and cornices, enclosed eave soffit spaces, enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters, underfloor ventilation, foundations and crawl spaces, or any other opening intended to permit ventilation, either in a horizontal or vertical plane. Ventilation openings shall be fully covered with Wildfire Flame and Ember Resistant vents approved and listed by the California State Fire Marshal, or WUI vents tested to ASTM E2886 and listed. CBC 706A/CRC R337.6
- Roof off ridge and ridge vents shall be covered with noncombustible corrosion resistant mesh. The vent product Net Free Ventilation Area (NFVA) may need to be adjusted based on the reduced mesh size and submitted for review. CBC 706A.2.1/1202.2/CRC R318.104.22.168/R806
- Exterior Wall Covering. CBC 707A.3/CRC R337.7.3
- Exterior Wall Assemblies. CBC 707A.4/CRC R337.7.4
- Open Roof Eaves. CBC 707A.5/CRC R337.7.5
- Enclosed Roof Eaves and Soffits. CBC 707A.6/CRC R337.7.6
- Exterior Porch Ceilings. CBC 707A.7/CRC R337.7.7
- Floor Projections. CBC 707A.8/CRC R337.7.8
- Underfloor Protection. CBC 707A.9/CRC R337.7.9
- Underside of Appendages. CBC 707A.10/CRC R337.7.10
- Exterior windows, skylights and exterior glazed door assemblies. CBC 708A.2.1/CRC R322.214.171.124
- Operable skylights. CBC 708A.2.2/CRC R3126.96.36.199
- Exterior Doors. CBC 708A.3/CRC R337.8.3
- Garage doors. CBC 708A.4/CRC R337.8.4
- Decking and deck-to-wall flashing. CBC 708A.4/CRC R337.9
Inspection and certification
Upon completion of construction, the final inspection report or certificate of occupancy demonstrate the building was constructed in compliance with all applicable state and local building standards, including those for materials and construction methods for wildfire exposure. Compliance with vegetation clearance requirements will be enforced by the local Fire Agency having jurisdiction. CBC 701A.4/CRC R337.1.4