Building an ADU in St. Paul
City code and Minnesota law · Last reviewed October 9, 2026
St. Paul allows up to two accessory dwelling units (ADUs) for each one-family home on a lot, in its RL through RM2 residential districts and a few others. Each ADU can be up to 800 square feet or 75% of the main home's floor area, whichever is greater, and an ADU in a detached building can be up to 25 feet tall. You don't have to live on the property, and you don't need to add parking. You apply for a building permit with the Department of Safety and Inspections (DSI), which reviews zoning at the same time. [1][2][3][4]
| Where ADUs are allowed | RL, H1, H2, RM1 and RM2 residential districts; T1-T3 traditional neighborhood; BC; F1 Ford [1] |
|---|---|
| How many | Up to two per one-family home on a lot; if two, at least one must be detached (unless you keep at least 50% of an existing house) [1][2] |
| Max size | 800 sq ft or 75% of the main home's floor area, whichever is greater (each ADU) [2] |
| Detached ADU height | 25 ft for an accessory building with a dwelling unit (RL-RM2 districts) [2][3] |
| Detached ADU setbacks | May sit in the rear yard; at least 3 ft from interior lot lines (more in some yard locations) and 1 ft from an alley [1][3] |
| Parking | No minimum number of parking spaces [3] |
| Owner occupancy | Not required (removed in 2022) [1] |
| Occupancy limit | Main home and its ADUs together: no more than six adults plus the minors in their care [1][2][11] |
| SAC and parkland fees | SAC $2,485 per unit plus $175 processing; parkland dedication $1,200 per unit (capped at 4.5% of land value) [4][8] |
| Selling the ADU separately | Not allowed; no separate tax parcel [2] |
| Short-term rental | Allowed with a city host license (stays under 30 days) [12][13] |
On this page
What you can build here
St. Paul defines an ADU as a dwelling unit "secondary to a principal one-family dwelling, within or attached to the one-family dwelling or in a detached accessory building on the same zoning lot." A detached ADU can be in a building that includes a garage.
St. Paul first allowed ADUs in a limited area in 2016 and citywide in 2018. In 2022 it dropped the owner-occupancy rule and the minimum lot size for detached ADUs. Ordinance 23-43, in effect since November 26, 2023, allowed two ADUs per one-family home, raised the size limit and set a 25-foot height limit for detached ADUs.
You can have up to two ADUs for each one-family home on a lot. If you have two, at least one must be detached, unless you keep at least 50% of the floor area of an existing house, in which case both can be attached. Other housing, such as a duplex, can share the lot with the one-family home and its ADUs.
ADUs don't count toward a district's maximum number of principal units. In the H1 district, for example, you can have up to four principal units (with 1,500 square feet of lot per unit), and ADUs are on top of that. For what state law says, see our Minnesota ADU page. [1][2][5][6]
Size, height and setbacks
Size. Each ADU can have up to 800 square feet of floor area or 75% of the floor area of the main home, whichever is greater. Floor area is measured from the inside faces of the exterior walls.
Height. An ADU attached to the house follows the district's height limit for the house. In RL through RM2 districts, an accessory building with a dwelling unit can be up to 25 feet tall. Historic sites and districts set accessory building heights through design review.
Setbacks for a detached ADU follow the accessory building rules:
- It can be in the required rear yard, at least 1 foot from an alley.
- It must be at least 3 feet from all interior lot lines. Overhangs must be set back at least one-third of the wall's setback or 1 foot, whichever is greater. In a nonrequired front or rear yard next to a side or front yard, it must instead meet the house's minimum side yard.
- On a corner lot, it must be as far from the side street as the house must be.
- A building less than 6 feet from the house counts as attached for setback and lot coverage.
An attached ADU follows the district's setbacks for the house. The district's maximum lot coverage applies to all buildings combined; in H1 it is 45% of the lot.
Entrances. You need a walkway from the street to the ADU's main entrance. An upper-floor unit in the house needs an interior stair to its entrance. Exterior fire stairs can be on the side or rear but not the front, and must match the building's finish; raw lumber is not allowed. [1][2][3][6]
Parking
St. Paul's zoning code says, "There are no requirements for a minimum number of parking spaces." If you do add parking, access must come from the alley when there is one, and parking spaces can't be in the front yard. [3]
Fees
DSI's ADU checklist lists these parts of the permit cost:
- Building permit fee from the valuation table. On the fee schedule effective February 25, 2023, work valued at $100,001 to $500,000 costs $1,499 for the first $100,000 plus $8 for each additional $1,000. Work valued at $99,001 to $100,000 costs $1,522.
- Plan check fee: 65% of the building permit fee.
- State surcharge: the project valuation times 0.0005.
- Zoning design review fee: $357.
- Sewer availability charge (SAC): $2,485 per unit plus a $175 processing fee.
- Parkland dedication fee: $1,200 per dwelling unit, up to 4.5% of the county assessor's estimated market value of the land.
Credit is given for prior construction. DSI's ADU handout says SAC and parkland fees together could add up to $3,860, due when the building permit is issued. The building permit page still links the 2023 fee schedule, so confirm current amounts with DSI. See our ADU cost guide for whole-project budgeting. [4][7][8][9]
Building code, garages and utilities
ADUs must meet the 2020 Minnesota Residential Code and are treated like any other new dwelling unit. Frost-protected footings are required for every ADU. DSI warns that "a standard monolithic garage slab/foundation with turned-down footings is not adequate for an ADU." That matters if you plan to convert an existing garage; see our garage conversion guide.
Attached and internal ADUs need a one-hour fire and sound separation from the main home. Mechanical, plumbing and electrical must be metered separately, and each unit needs access to its own utilities and shut-offs.
A detached ADU is a separate building, so the state plumbing code generally requires its own water and sewer connections. Connecting through the main house is possible only with an approved alternate request, case by case, and only if the house's plumbing is code compliant. Connections to the street go through Saint Paul Regional Water Services for water and the city Sewer Utility for sewer. [1][4][8][10]
Occupancy and ownership
You don't have to live on the property; St. Paul removed that requirement in 2022. But the main home and its ADUs together can't exceed one "household," which the code defines as "six (6) or fewer adults, and minor children in their care." For example, if four adults live in the house, only two adults can live in the ADU.
ADUs "must not be sold separately from the principal dwelling unit, and may not be a separate tax parcel." [1][2][11]
Renting it out short term
A short-term rental in St. Paul is a dwelling or part of one rented for less than 30 days. You need a city host license, renewed every year. Short-term rentals can't be used for commercial or social events. The license application lists an ADU as a possible unit.
For an owner-occupied single-family building, one short-term rental unit is allowed and no Fire Certificate of Occupancy is needed. Non-owner-occupied rentals need Fire Certificate of Occupancy paperwork. Hosts must carry at least $300,000 in liability insurance or book through a platform that provides equal coverage. See the city's short-term rental page. [12][13]
Permit steps in St. Paul
Check your zoning district
Find your district on the city's zoning map. ADUs are allowed in RL, H1, H2, RM1 and RM2 residential districts, T1-T3, BC and F1, and only with a one-family home on the lot. [1][5]
Talk to plan review and zoning staff
For one- and two-unit projects, you can arrange a meeting with Building Plan Review staff by calling 651-266-9007. Zoning questions about design, setbacks, height and lot coverage go to 651-266-9008. [4][5]
Check sewer and water before you design
Under the state plumbing code, a detached ADU generally needs its own water and sewer connections to the street. Connecting through the main house needs an approved alternate code request from a master plumber or licensed engineer, decided case by case. [1][10]
Prepare your plans
You need a certified survey signed by a licensed surveyor, civil plans with utilities, ADU floor plans and elevations, and floor plans of the main home to verify the ADU's size. Plans must meet the 2020 Minnesota Residential Code. Use the city's new construction checklist for ADUs. [1][4][8]
Apply for a building permit in PAULIE
Since September 17, 2025, St. Paul takes permit applications in PAULIE, its online permitting system. Zoning review happens automatically with the building permit once plans are submitted. [4][14]
Get historic approval if it applies
If your property has local historic designation, you may need Heritage Preservation Commission approval before the permit is issued. [5]
Pay fees and start work
SAC and parkland dedication fees come on top of the permit, plan review and zoning fees, and are due when the building permit is issued. Projects over $25,000 also need a signed Construction Management Acknowledgement form before work starts. [4][8]
Who to call
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Building permit and plan review questions for one- and two-unit projects, including ADUs; desk open Monday to Friday 8 a.m. to 4 p.m.
375 Jackson Street, Suite 220, Saint Paul, MN 55101
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Zoning questions on design, setbacks, height, lot coverage and openings; email dsi-zoning@ci.stpaul.mn.us
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Department of Safety and Inspections (main line)
General DSI questions, including short-term rental licenses
375 Jackson Street, Suite 220, Saint Paul, MN 55101
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Saint Paul Regional Water Services
Water service and water meter permits and fees
-
Permits and fees for sewer work outside the building
Questions people ask
How many ADUs can I build in St. Paul?
Up to two for each one-family home on a lot. If you build two, at least one must be detached, unless you keep at least 50% of the floor area of an existing house. [2]
How big can an ADU be in St. Paul?
Each ADU can be up to 800 square feet or 75% of the main home's floor area, whichever is greater. An ADU in a detached building can be up to 25 feet tall in RL through RM2 districts. [2][3]
Do I have to live on the property to have an ADU in St. Paul?
No. St. Paul removed the owner-occupancy requirement in 2022. The house and its ADUs together are limited to six adults plus the minors in their care. [1][2]
Can I convert my garage into an ADU in St. Paul?
An ADU can be in a detached accessory building that includes a garage. Every ADU needs frost-protected footings, and DSI says a standard monolithic garage slab with turned-down footings is not adequate. A detached ADU also generally needs its own water and sewer connections. [1][8][10]
Do I need a parking space for an ADU in St. Paul?
No. St. Paul's zoning code has no minimum number of parking spaces. [3]
Sources (14)
- Accessory Dwelling Units (last edited March 6, 2024), City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- Saint Paul Legislative Code, Sec. 65.913: Dwelling unit, accessory, City of Saint Paul (Municode). Accessed October 9, 2026.
- Saint Paul Legislative Code, Chapter 63: Zoning Code, Regulations of General Applicability (Secs. 63.201 and 63.501), City of Saint Paul (Municode). Accessed October 9, 2026.
- New Construction Checklist for Single Family, 2 Family, Townhome and Accessory Dwelling Unit (ADU), City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- 1-6 Unit Housing Development in RL, H1, and H2 Residential Zoning Districts (last edited May 26, 2026), City of Saint Paul, Department of Planning and Economic Development. Accessed October 9, 2026.
- H1 Residential District, City of Saint Paul, Department of Planning and Economic Development. Accessed October 9, 2026.
- Building Permit Fee Schedule (effective February 25, 2023), City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- Accessory Dwelling Units and the Building Code, City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- Building Information & Applications (last edited August 31, 2026), City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- Accessory Dwelling Unit (ADU): sewer and water connections, City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- Saint Paul Legislative Code, Sec. 60.209: H (definition of household), City of Saint Paul (Municode). Accessed October 9, 2026.
- Short Term Rentals, City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- Short Term Rental Host License Application (1-21-25), City of Saint Paul, Department of Safety and Inspections. Accessed October 9, 2026.
- PAULIE: New Permitting and Licensing System, City of Saint Paul. Accessed October 9, 2026.