Accessory Structures in St. Louis, MO (2026)
9 verified accessory structures rules for St. Louis, Missouri, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
St. Louis allows accessory dwelling units in many residential zones through a 2023 zoning code update supporting infill housing.
Accessory Structures: Adu Rules
Some RestrictionsADU Permits
St. Louis allows accessory dwelling units in several residential zoning districts following the 2021 ADU reform under Ordinance 71591, which amended the City's Zoning Code (SLRC Title 26). ADU applications are processed by the Building Division within the Department of Public Safety, with zoning review by the City Planning Commission staff. Missouri has no statewide ADU mandate.
St. Louis ADU Permits and Zoning Code Process
Some RestrictionsADU Impact Fees
St. Louis does not charge true impact fees on ADUs because Missouri has not granted municipalities statutory authority to impose development impact fees on residential construction. ADU costs are limited to Building Division permit fees, plan-review charges, and Metropolitan St. Louis Sewer District (MSD) and city water connection charges based on actual service.
St. Louis ADU Impact Fees (None — Missouri Lacks State Authorization)
Few RestrictionsADU Owner Occupancy
St. Louis's Zoning Code (SLRC Title 26) does not impose a blanket citywide owner-occupancy mandate on ADUs following the 2021 reforms. However, both the primary dwelling and the ADU, if rented to non-owners, must comply with the City's Occupancy Permit requirement under SLRC Title 25 and any applicable Local Historic District guidelines. Missouri has no state preemption — STL retains full home-rule discretion.
St. Louis ADU Owner-Occupancy Rules
Some RestrictionsADU Rental Restrictions
St. Louis ADUs may be rented long-term (30+ days) subject to the City's Occupancy Permit requirement under SLRC Title 25. Short-term rentals under 30 days are regulated by St. Louis Revised Code Chapter 11.55 (Short-Term Rental Ordinance, Ordinance 71596), which requires a Short-Term Rental Operator Permit and collection of the 3.5% Convention and Tourism Tax plus state and local sales taxes.
St. Louis ADU Rental and Short-Term Rental Rules
Some RestrictionsShed Rules
St. Louis allows residential sheds up to 200 sq ft without a building permit but requires zoning compliance under Ord. §26.52. Sheds must be set back at least 3 ft from rear and side lot lines, cannot exceed 12 ft in height, and may not be placed in front yards or easements.
accessory-structures/shed-rules
Some RestrictionsGarage Conversions
Converting a garage into livable space in St. Louis requires a Building Division permit, zoning review, and compliance with residential code.
Accessory Structures: Garage Conversions
Some RestrictionsCarport Rules
Carports are treated as accessory structures in St. Louis and must comply with setback, size, and design review rules. Permits are required for any carport regardless of size.
Accessory Structures: Carport Rules
Some RestrictionsTiny Homes
Tiny homes on permanent foundations are allowed in St. Louis as ADUs or primary dwellings subject to zoning district minimums, building code, and historic district review.