Washington Statewide Rule

Washington State Wildland Urban Interface Code

Heavy RestrictionsApplies statewide across Washington (2026)

Key Facts

Statute: RCW 19.27.560
Code adopted: International WUI Code (2021)
Effective date: July 1, 2023
Mapping authority: Department of Natural Resources

Last verified: August 20, 2026Source: Washington State Legislature

Summary

Washington adopted the International Wildland-Urban Interface Code statewide under RCW 19.27.560, effective July 1, 2023. New construction in designated WUI areas must meet ignition-resistant building, defensible space, and water supply requirements.

International Wildland Urban Interface Code — Local wildfire hazard and base-level wildfire risk maps. (1) In addition to the provisions of RCW 19.27.031 , the state building code shall, upon the completion of a statewide wildfire hazard map and a base-level wildfire risk map for each county of the state, per RCW 43.30.580 , consist of chapter 1 and the following technical provisions of the International Wildland Urban Interface Code, published by the International Code Council, Inc., which are hereby adopted by reference: (a) The following parts of class 1 ignition-resistant construction: (i)(A) Roof covering - Roofs shall have a roof assembly that complies with class A rating when testing in accordance with American society for testing materials E 108 or underwriters laboratories 790. For roof coverings where the profile allows a space between the roof covering and roof decking, the space at the eave ends shall be fire stopped to preclude entry of flames or embers, or have one layer of seventy-two pound mineral-surfaced, nonperforated camp sheet complying with American society for testing materials D 3909 installed over the combustible decking.

Source: Washington State LegislatureView official code

Full Breakdown

Under RCW 19.27.560, Washington adopted the International Wildland-Urban Interface Code (IWUIC), effective July 1, 2023. New construction and substantial alterations in mapped wildland-urban interface areas must use ignition-resistant exterior materials, ember-resistant vents, defensible space, and adequate water supply for fire suppression. The Department of Natural Resources publishes statewide wildfire hazard maps, and enforcement of RCW 19.27.560 applies to parcels DNR maps as high or very high hazard. Local jurisdictions may adopt the full IWUIC but cannot weaken state minimum requirements.

Violations & Penalties

Building code violations may result in stop work orders, civil penalties, denial of certificates of occupancy, and removal of non-compliant construction.

Frequently Asked Questions

How do I know if my property is in a WUI zone?

The Washington Department of Natural Resources publishes wildland-urban interface maps under RCW 76.04. Contact your local building department or DNR to verify your property's status.

Do existing homes need to retrofit?

The IWUIC primarily applies to new construction and substantial alterations. Existing structures generally are not required to retrofit unless undergoing major renovations triggering code compliance.

Sources

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