Thurston County, WA Sign Regulations: Window Signs (2026)

Thurston County's Grand Mound Design Guidelines, Chapter 20.36, apply to new commercial, industrial, and multifamily development (five or more units) in the Arterial Commercial, Planned Industrial, Light Industrial, Residential 3-6, and Residential 4-16 zoning districts within the Grand Mound Urban Growth Area, an unincorporated growth area centered on the Interstate 5/US 12 interchange. Section 20.36.050(1) makes clear these sign guidelines are additional to, not a substitute for, the countywide sign regulations in Chapter 20.40. Under the wall-sign criteria for Arterial Commercial and other commercial uses, Section 20.36.050(2)(a)(ii)(G) caps window signage at thirty percent of pedestrian-level windows, and an identical thirty-percent cap applies separately to industrial uses in the Planned Industrial and Light Industrial districts under Section 20.36.050(2)(b)(ii)(E).

The same subsection also bars wall signs from extending above the building's eave or parapet, ties the maximum wall sign allowance to street frontage (two square feet per linear foot up to 360 square feet for single-occupancy commercial buildings), and permits one pedestrian-oriented sign per business entrance. Any nonconforming sign that is structurally altered, defined as any action changing a sign's height, size, shape, or its base or supports, loses its legal nonconforming status and must be brought into full compliance with these guidelines, including the window coverage cap, under Section 20.36.020(2)(d).

A sign that is damaged, deteriorated, or abandoned for six months or more, and whose repair costs exceed fifty percent of its value, must likewise be brought into conformance under Section 20.36.050(3)(a).