King County, WA Building Safety: Green Building Code (2026)
Key Facts
- Applies to
- County-owned capital projects only
- New county buildings
- LEED Platinum or better required
- Major remodels
- LEED Gold minimum
- Private construction
- No mandatory certification requirement
- Waivers
- Reviewed by county executive
Summary
Unincorporated King County has no mandatory green building code for private construction. Chapter 18.17 requires LEED Platinum or Living Building Challenge certification only for county-owned capital projects and county-financed affordable housing, not homes or businesses built under a standard permit.
New construction of a LEED-eligible building shall achieve:
(1) either LEED platinum certification or the Living Building Challenge certification, or both, if the project is initiated before January 1, 2026; or
(2) either LEED Platinum plus Zero Energy or Zero Carbon certification, or Living Building Challenge CORE plus Zero Energy, Energy Petal, or Zero Carbon Certification, if the project is initiated on or after January 1, 2026;; and
b. A major remodel or renovation of a LEED-eligible building shall achieve either LEED gold certification or the Living Building Challenge certification, or both;
4. Capital projects owned or lease-to-own by King County that are large-scale infrastructure or site-related projects shall achieve Envision Platinum certification. This requirement is limited to: new construction of conveyance, combined sewer overflow, and pump station projects from the wastewater treatment division that are over a cost threshold established by executive policy; new RapidRide and bus base electrification charging infrastructure projects by Metro transit department; and heavy-duty electrical infrastructure projects with ten or more direct-current fast chargers by the solid waste division;
Full Breakdown
K.C.C. 18.17.025.C limits the county's green building program to King County-owned or lease-to-own capital projects. Under K.C.C. 18.17.050.A.3.a, new construction of a county LEED-eligible building must achieve LEED Platinum or Living Building Challenge certification, with stricter zero-energy tiers after January 1, 2026, and a major remodel must reach LEED Gold. County-financed affordable housing must meet the Evergreen Sustainable Development Standard under K.C.C. 18.17.050.A.2.a. Private residential and commercial construction permitted through the department of local services carries no such mandate; the county instead offers a green building grant program under K.C.C. 18.17.030 and voluntary educational materials under K.C.C. 18.17.110.A.
Violations & Fines
No penalty applies to private builders because no mandate reaches them. For county capital projects, K.C.C. 18.17.060 lets the executive grant a compliance waiver when certification costs are unreasonable or benefits do not justify them.
Frequently Asked Questions
Do I need LEED certification to build a house in unincorporated King County?
What green standard must new King County government buildings meet?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington building safety overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.