Thurston County, WA Swimming Pools & Spas: Pool Permits (2026)

Item 9 of § 14.17.030's exemption list excuses a "prefabricated swimming pool accessory to a Group R-3 occupancy" from Thurston County's building-permit requirement, but only if it is "less than twenty-four inches (610 mm) deep," holds no more than "five thousand gallons (18,925 l)," and is "installed entirely above ground." Group R-3 covers single-family houses and similar residential occupancies, so the exemption is built for a backyard pool at a private home, not a pool serving a multifamily building or a commercial property.

A pool that is deeper than twenty-four inches, holds more than five thousand gallons, or is set into or below grade needs a permit under § 14.17.030's general rule, [A]105.1: the property owner or an authorized agent must apply to the Community Planning and Economic Development Department before construction starts, pay the fee set under § 14.17.050, and complete an inspection before the one-year permit expires. Because pool work often ties into grading, drainage, or fencing around the water, exempt work can still trigger review under other chapters, including Titles 15 through 25, even when the pool itself needs no permit.

Installing an oversized or in-ground pool without first securing that permit exposes the owner to § 14.17.060's civil-infraction and misdemeanor penalties: a class 1 civil infraction under Chapter 7.80 RCW for building without a permit, with a separate infraction for each day of continued work, and a misdemeanor backstop of up to $1,000 and ninety days in jail under [A]114.5.