Zoning Overlays & Bonuses in King County, WA (2026)

2 county-level rules, plus city-specific rules for 6 cities in King County, Washington.

Verified from official government sources

Note: These county rules apply to unincorporated areas of King County. If you live within an incorporated city, that city's own rules apply: see the city list below.

Density Bonus Law

Unincorporated King County developments get bonus density or floor area for adding improved child daycare slots, up to 25% more dwelling units than the base zone allows.

King County Child Daycare Density Bonus

Some Restrictions

King County Code § 21A.12.270

For every six child daycare slots provided, the development shall receive one of the following: 1. One additional bonus dwelling unit, up to an additional twenty-five percent of base density; or 2. One-thousand square feet of nonresidential floor area added to the floor area ratio maximum. C. At least twenty percent of child daycare slots shall be reserved for households at or below e...

Full ordinance details →Official source ↗

Downtown Design Guide

Unincorporated King County has no countywide downtown design code: only the North Highline subarea (the White Center activity center) has adopted urban design standards under K.C.C. 21A.09.070, governing site layout, streetscape, and building character for new commercial and multifamily development there.

King County North Highline Urban Design Standards

Some Restrictions

King County Code § 21A.09.070

The North Highline urban design standards are hereby established. ... shall apply to: 1. All new buildings or substantial improvements to developments in the CB, NB, RB, O, R-12, R-18, R-24, and R-48 zones; and 2. Modification to any existing building that affects its exterior appearance in the White Center unincorporated activity center land use designation, except for single detached dwelling...

Full ordinance details →Official source ↗