St. Louis County, MO Swimming Pools & Spas: Pool Permits (2026)
Swimming pool permit rules in St. Louis County, MO, also covering above-ground pools, in-ground pools, and spa installations, set fencing, barrier, alarm, and inspection requirements.
Key Facts
- Governing code
- Ch. 1118 SLCRO (2015 ISPSC), § 1115.105
- Permit required for
- Any pool construction, alteration or demolition
- Exempt pools
- 24 in. deep or less, 5,000 gal. max, above-ground
- Enforcing agency
- Dept. of Transportation and Public Works
- No-permit penalty
- Greater of $500 or 1% of cost
- General violation fine
- Up to $1,000 or 90 days jail
- Appeal body
- Building Commission / Board of Appeals
Summary
Anyone building, enlarging, or altering a residential swimming pool in unincorporated St. Louis County must first obtain a permit from the Department of Transportation and Public Works under the county's Swimming Pool and Spa Code, Chapter 1118, which routes every permit question to the county's own Building Code. Only small prefabricated above-ground pools holding no more than 5,000 gallons at a maximum 24-inch depth skip the permit step entirely.
105.1 Required. Any owner or owner's authorized agent who intends to construct, enlarge, alter, repair, move, demolish, or change the occupancy of a building or structure, or install or alter a ground level paved parking lot other than those lots serving a single-family dwelling, or establish a new or relocated lot line that affects an existing structure, or to erect, install, enlarge, alter, repair, remove, convert or replace any electrical, gas, mechanical or plumbing system, the installation of which is regulated by this code, or to cause any such work to be performed, shall first make application to the building official and obtain the required permit. ... 7.Prefabricated swimming pools accessory to one- and two-family dwellings, townhouses and Group R-3 occupancies which have a maximum water depth of 24 inches (610 mm), a maximum water volume of 5,000 gallons (18925 L) and are installed entirely above ground.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 85 | Traffic: Supplement 80).
Full Breakdown
St. Louis County adopted the 2015 International Swimming Pool and Spa Code as Chapter 1118 SLCRO by Ordinance No. 27654, effective April 1, 2020, covering the construction, alteration, replacement, repair, equipment, location and demolition of every swimming pool and spa in the unincorporated county. Rather than reprint its own permitting chapter, Section 1118.101 deletes Section 105 Permits from the model pool code outright and substitutes Section 105 Permits from the International Building Code, meaning pool permits run on the identical rule the county uses for house additions and garages: Section 105.1 requires any owner or authorized agent who intends to construct, enlarge, alter, repair, move, or demolish a regulated structure to first make application to the building official and obtain the required permit.
The exemption that matters to most homeowners sits in Section 105.2(7): a prefabricated pool is exempt only if it serves a one- or two-family dwelling, holds a maximum water depth of 24 inches, a maximum volume of 5,000 gallons, and sits entirely above ground. Anything deeper, bigger, or built in-ground needs a permit before construction starts, including electrical sign-off for pumps and lighting under Section 1118.103's NFPA 70 reference. The Director of the Department of Transportation and Public Works, acting as Code Official, reviews applications, and any municipality that contracts with the county for enforcement must also clear the plans for zoning compliance under Section 1118.051 before the county issues a permit.
Permit fees are set in Chapter 1100 SLCRO, and the building official can grant modifications for practical difficulties under Section 104.10, with extra scrutiny for pools in flood hazard areas under Section 104.10.1.
Violations & Fines
Building without the required permit exposes the owner to a stop-work order and a no-permit penalty of the greater of $500 or 1 percent of the construction cost, assessed under Section 114.4.1, on top of the general Building Code penalty of up to $1,000 and 90 days in jail for any code violation, with each day of continued noncompliance treated as a separate offense under Section 114.4. No-permit penalties can be appealed to the Board of Appeals.
Frequently Asked Questions
Do I need a permit for an above-ground pool in St. Louis County?
Which department issues residential pool permits?
What happens if I build a pool without a permit?
Can I appeal a denied pool permit or an assessed penalty?
Sources & Official References
Other rules in St. Louis County
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