The State Building Code. The State Building Code (Code) establishes minimum performance standards and requirements for construction and construction materials in the state, consistent with accepted standards of engineering, fire, and life safety. The Code comprises a number of model codes and standards, developed and published by international and national organizations, which are adopted by reference in the State Building Code Act (Act). Model codes and standards adopted in the Act include the International Building Code, International Residential Code, the International Mechanical Code, the International Fire Code, and the Uniform Plumbing Code Standards. 

The State Building Code Council (Council) is responsible for adopting, amending, and maintaining as appropriate the model codes and standards adopted by reference in the Act. Amendments to the model codes and standards adopted by the Council are codified in the Washington Administrative Code. The Council regularly reviews updated editions of each model code and standards every three years. 

The International Wildland Urban Interface Code. The International Wildland Urban Interface (WUI) Code is a model code developed and published by the International Code Council, Inc. (ICC). The ICC is a nonprofit organization that develops and publishes model codes for building, construction, and design standards. Updates to the codes are developed and published on a three-year cycle. 

The International WUI Code establishes minimum regulations for land use and the built environment in designated WUI areas for the stated purpose of mitigating wildfire hazard. The International WUI Code applies to the construction, alteration, movement, repair, maintenance, and use of any building, structure, or premises within the WUI areas of a jurisdiction. WUI area is defined in the International WUI Code as the geographical areas where structures and other human development meets or intermingles with wildland or vegetative fuels.

Department of Natural Resources. Department of Natural Resources (DNR) has the direct charge and responsibility over all matters pertaining to forest fire services in the state. The forest fire-related duties of DNR include enforcing all forest fire-related laws, investigating the cause of forest fires, and directing fire suppression efforts. In 2019, DNR developed a wildland-urban interface map utilizing the United States Department of Agriculture Forest Service Wildfire Hazard Potential data. This map is not a wildfire risk map, but a tool used to help define wildfire risk. 

Under current law, upon completion of the statewide mapping of WUI areas, the following portions of the 2018 International WUI Code, published by the ICC, are added to the State Building Code:

• 504.2?class A roof covering, except that roofs on additions or an existing structure that has more than 50 percent replaced must meet requirements for new construction;
• 504.5?exterior walls;
• 504.7?appendages and projections, except that unenclosed accessory structures on the first floor must be built with building materials at least two inches nominal depth and the area below the structure to be screened with wire mesh screening; and
• 403.2?driveways, except that turnarounds are required for driveways in excess of 300 feet in length and turnouts are also required for driveways in excess of 500 feet in length and less than 20 feet in width. The county, city, or town will define the requirements for a turnout or turnaround.

All cities, counties, and towns may adopt International WUI code, or any portion thereof. In adopting and maintaining the International WUI Code, the Code adopted may not result in an International WUI Code that is more than the minimum performance standards and requirements contained in the published model code. DNR must, to the extent practical within existing resources, establish a program of technical assistance for development of finding of fact and maps establishing WUI areas in accordance with the requirements of the International WUI Code, and develop and administer a grant program for counties, cities, and towns, subject to funding provided for this purpose.

Upon the completion of a statewide map of areas at greatest risk from wildland fire, the State Building Code Council may only adopt those portions of the International Wildland Urban Interface Code as set forth in statute, which includes: 

• class A roof covering, except that roofs on additions or an existing structure that has more than 50 percent replaced must meet requirements for new construction;
• exterior walls;
• appendages and projections, except that unenclosed accessory structures on the first floor must be built with building materials at least two inches nominal depth and the area below the structure to be screened with wire mesh screening; and
• driveways, except that turnarounds are required for driveways in excess of 300 feet in length and turnouts are also required for driveways in excess of 500 feet in length and less than 20 feet in width. The county, city, or town will define the requirements for a turnout or turnaround.

All counties, cities and towns may complete their own map of areas at greatest risk from wildfire for use in applying the International Wildland Urban Interface Code. Any map adopted by counties, cities, and towns must utilize the same or substantially similar criteria as the statewide map developed by DNR. All counties, cities, and towns issuing commercial and residential building permits in areas identified as high risk or very high risk on the statewide map or local map of areas at greatest risk from wildfire must apply the code as adopted by the State Building Code Council.