Is St. Louis City the same as St. Louis County?

No — and this is a critical distinction. St. Louis City is an independent city that separated from St. Louis County in 1876. The City is not part of any county and functions as its own county-equivalent. When searching for zoning, permit, or land use information, make sure you are looking at St. Louis City resources (stlouis-mo.gov), not St. Louis County resources (stlouisco.com). Properties within city limits use the City's zoning code; properties in the suburbs use St. Louis County or their respective municipality's codes.

Can I build an ADU on my St. Louis rowhouse lot?

Yes. St. Louis allows ADUs in residential zones. The traditional St. Louis rowhouse lot typically has a rear yard with alley access — the natural location for a detached ADU or carriage house conversion. No replacement parking is required. Contact the St. Louis Building Division for current requirements and the Planning and Urban Design Agency for zoning questions. If your home is in a local historic district (Soulard, Lafayette Square, etc.), you'll need a Certificate of Appropriateness before building.

What is the St. Louis City home business permit process?

St. Louis does not require a separate home occupation permit, but home businesses must comply with zoning code restrictions: no customers visiting the premises in residential zones A-E, no exterior signage, no non-resident employees, and no more than 25% of floor area used for business. If you plan to operate a business requiring a state or city license (e.g., daycare, food service, professional services), contact the St. Louis License Collector for applicable license requirements.

How does St. Louis handle short-term rentals like Airbnb?

St. Louis requires an STR license ($200/year) for rentals of less than 31 consecutive days. Both hosted (room rental while owner is present) and whole-home rentals may be allowed depending on the zone. All listings must include the license number. St. Louis imposes a Hotel/Motel Guest Tax on STR revenues in addition to Missouri state sales tax. Contact the St. Louis License Collector at (314) 622-4111 for current licensing requirements.

My home is in the Soulard Historic District — what does that mean for renovations?

Soulard is one of St. Louis's most celebrated historic neighborhoods, designated as both a local historic district and a National Register Historic District. For exterior changes (including additions, window replacements, siding, fences, roofing material changes, and ADU construction visible from public right-of-way), you must obtain a Certificate of Appropriateness from the St. Louis Preservation Board before beginning work. Interior changes do not require Preservation Board review. Applications are reviewed at monthly Preservation Board meetings. Contact the Cultural Resources Office at (314) 622-3400.

Can I Build?

Can I Build ADU in St. Louis, MO? (2026)

Find out if you can build a adu in St. Louis, MO. Rules, permit requirements, costs, and next steps.

Conditional

Whether ADUs are allowed in St. Louis, MO has not been confirmed — contact the local building department or see the official source before proceeding.

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a residential lot — also called a granny flat, in-law suite, or backyard cottage. In St. Louis, MO, ADU regulations are in flux — state law and local ordinances interact to determine what is permitted. ADUs can be detached, attached to the main home, or created by converting an existing garage or accessory structure.

ADU Rules in St. Louis

ADU Rules in St. Louis: Detached ADU max size: size varies by zoning — see official source. Attached ADU max size: size varies by zoning — see official source. Setback requirements are not confirmed — see official source. Owner-occupancy: not confirmed — see official source.

Costs & Fees

ADU permits in St. Louis: Contact the local building department for current fee schedule.

Next Steps

Next steps for building an ADU in St. Louis: 1. Review full ADU rules including size limits, setbacks, and parking. 2. Apply for an ADU permit through the local building department. 3. Hire a licensed contractor familiar with MO ADU requirements.

View Full ADU Rules ADU Permit Requirements

St. Louis Building Division (Community Development Administration)

Phone: See official source

Website: https://stlouis-mo.gov/government/departments/building

Online Permits: https://stlouis-mo.gov/government/departments/building/permits.cfm

Frequently Asked Questions

See official source

Source: St. Louis Building Division (Community Development Administration) — Building Regulations. Last verified April 6, 2026. View source

Last updated: April 6, 2026

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