King County, WA Outdoor Lighting: Billboard Lighting (2026)
Key Facts
- Governing section
- K.C.C. 21A.20.060(F)
- Light source distance
- No farther than sign height
- Direct rays
- Barred from homes, streets
- Blinking on/off signs
- Only CB, RB, I zones
- Coverage
- Unincorporated area only, not Seattle
Summary
Unincorporated King County allows billboards to be illuminated, but light sources must sit no farther from the sign than its height and can't shine directly into homes or streets.
F. Regarding sign illumination and glare:
1. Except as otherwise provided in this chapter, all signs may be illuminated;
2. The light source for indirectly illuminated signs shall be no farther away from the sign than the height of the sign;
3. Indirectly and directly illuminated signs shall be arranged so that no direct rays of light are projected from such artificial source into residences or any street right-of-way;
4. Electrical requirements for signs shall be governed by chapter 19.28 RCW and WAC 296-46-910; and
5. Signs with an on/off operation shall be permitted only in the CB, RB and I zones.
G. Maximum height for wall signs shall not extend above the highest exterior wall or structure upon which the sign is located.
H. Maximum height for projecting signs shall not extend above the highest exterior wall upon which the projecting sign is located.
I. Maximum height for awning signs shall not extend above the height of the awning upon which the awning sign is located.
J. Any sign attached to the sloping surface of a roof shall be installed or erected in such a manner that there are no visible support structures, shall appear to be part of the building itself, and shall not extend above the roof ridge line of the portion of the roof upon which the sign is attached.
K. Except as otherwise permitted by this chapter, off-premise directional signs shall not exceed four square feet in sign area.
Full Breakdown
King County Code Section 21A.20.060.F governs illumination and glare for all signs in unincorporated King County, including billboards, which count as signs under the code. Signs may be illuminated unless a specific rule says otherwise, but an indirectly illuminated sign's light source can't sit farther from the sign than the sign's own height, and both direct and indirect light must be aimed so no rays hit neighboring residences or a street right-of-way. Signs wired for on/off blinking operation are restricted to the CB, RB and I zones. King County's Department of Local Services enforces these standards through permitting and code compliance.
Violations & Fines
Sign permits are required countywide; illuminated signs violating the glare or on/off restrictions can be cited through King County code enforcement and ordered corrected or removed.
Frequently Asked Questions
Does this rule cover billboards inside Seattle?
Can a billboard use blinking or flashing lights?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington outdoor lighting overview
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