Thurston County, WA Building Setbacks & Zoning: Lot Coverage Limits (2026)

12 governs the Low-Density Residential District 0-6, an urban growth area zone allowing single-family homes at up to six units per acre plus duplexes, triplexes, cottage housing, townhouses and accessory dwelling units. 050, Development standards, adopted by Ord. No. 16332 on December 12, 2023 (replacing the former 0-4 density chapter), sets the numeric table governing every new lot: minimum lot area of 4,500 square feet where alleys serve the lot or 5,000 square feet without alleys, minimum lot width of 40 or 50 feet, a 16-to-20-foot front yard depending on whether a garage faces the street, a 10-foot front yard on a flanking street, 5-foot minimum side yards and a 15-foot rear yard.

Coverage is capped in two tiers: maximum building area coverage of 50% of the lot, covering the footprint of the house and any accessory structures, and a broader maximum development coverage of 65%, plus a 25-foot maximum height. A separate 10% usable-open-space requirement must be contiguous and cannot sit in the front yard. Footnote 5 to the table exempts small accessory buildings, those under 200 square feet, from the standard setbacks, cutting them to sixteen feet front, five feet side and three feet rear. 080.

Subsection B addresses lots without sewer: the health department must approve an alternative sewage-disposal plan, lots must be clustered between 5,000 and 10,890 square feet around one large reserve parcel held for future development, and the recorded plat must commit each lot owner to connect to sewer, at their own expense, once it becomes available. A general note allows alternative lot configurations if they meet a superior design standard weighing privacy, pedestrian access and open-space quality.