King County, WA Swimming Pools & Spas: Pool Permits (2026)
Swimming pool permit rules in King County, WA, also covering above-ground pools, in-ground pools, and spa installations, set fencing, barrier, alarm, and inspection requirements.
Key Facts
- Regulated Depth
- >24 inches deep
- Building Code
- WSRC Appendix G / AG105 (WAC 51-51)
- Min Barrier Height
- 48 inches above grade (outside)
- Pool Wall as Barrier
- ≥48 inches tall full perimeter
- Ladder Rule
- Removable, lockable, or secured when unattended
- Max Ground Clearance
- 4 inches under barrier
- Electrical
- NEC Article 680, Title 16 permit
- Critical Areas
- K.C.C. Chapter 21A.24 review may apply
- Confirm With
- King County DLS - Permitting (206) 296-6600
Summary
In unincorporated King County, an above-ground pool that can hold water more than 24 inches deep is regulated as a swimming pool under the Washington State Residential Code Appendix G/AG105 (WAC 51-51). It requires a building permit and a barrier at least 48 inches tall. The pool wall can serve as the barrier when it is 48 inches or taller, but ladders must be removable, lockable, or secured.
Building permits are required for most residential pool installations. Prefabricated swimming pools accessory to a single-family residence, that are less than 24-inches deep, do not exceed 5,000 gallons, and are installed entirely above ground, are EXEMPT from permits. An above ground pool over two feet deep, provides the barrier or the barrier is mounted on top of the pool's structure and the means of access is a ladder or steps they shall be provided as follows: P12. Where only the pool wall serves as the barrier, the bottom of the wall is on grade, the top of the wall is not less than 48 inches above grade for the entire perimeter of the pool... ALSO, the ladder or steps shall be capable of being secured, locked or removed to prevent access; OR The ladder or steps shall be surrounded by a barrier which meets the requirements of Items P1 through P11.
Full Breakdown
King County adopts the Washington State Residential Code (WAC 51-51), which incorporates IRC Appendix G - Section AG105 for residential pool barriers. The code defines a swimming pool as any structure intended for swimming or recreational bathing that contains water over 24 inches deep, so an above-ground or inflatable pool exceeding that depth is regulated and requires a King County building permit. AG105 requires the top of the barrier to be at least 48 inches above grade measured on the side facing away from the pool, with no more than 4 inches of clearance below and no openings allowing a 4-inch sphere.
Where the above-ground pool wall is 48 inches or more tall on the entire perimeter, the wall itself can serve as the barrier; in that case, ladders or steps must be removable, lockable, or otherwise secured when the pool is unattended, or surrounded by a separate compliant barrier. Electrical work for pumps and heaters requires a Title 16 electrical permit and must follow NEC Article 680. C. 24 (wetlands, streams, steep slopes, shoreline) may need additional review. Confirm with King County DLS - Permitting at 206-296-6600.
Violations & Fines
Installing an above-ground pool deeper than 24 inches without a building permit, leaving a fixed access ladder available when the pool is unattended, or having a pool wall under 48 inches without a separate compliant barrier violates WSRC AG105 and supports a stop-work order, a failed inspection, and a code-enforcement notice under K.C.C. Title 23.
Frequently Asked Questions
Do I need a permit for an above-ground pool in unincorporated King County?
Can the wall of an above-ground pool count as the safety barrier?
What barrier height does King County require?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington swimming pools & spas overview
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