St. Paul's 2023 zoning reform is one of the most ADU-friendly ordinances in Minnesota. Here's what homeowners need to know about size limits, setbacks, and permits.
Last verified: August 2026
9/10 · Very ADU-friendly
800 sq ft*
Max ADU size
25 ft
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes St. Paul Zoning Code §65.913 (Dwelling Units, Accessory) for general reference - it is not legal advice. Regulations change; always confirm current requirements with the St. Paul Department of Safety & Inspections (DSI) before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (accessory building)
800 sq ft or 75% of the principal dwelling's floor area, whichever is greater
25 ft
Requires its own lockable entrance, full kitchen, and full bathroom
Attached / internal (basement, addition)
Sized within the primary structure
Same as primary structure
Common for basement conversions
Lot size minimum
Eliminated under Ordinance 23-43 - no minimum lot size is required to qualify.
Additional standards
Setbacks, parking & other rules
Units per lot
Up to 2 ADUs permitted in addition to the principal dwelling
Owner-occupancy
Not required - you don't need to live on site to rent out an ADU or the main house, provided each is properly rental-licensed
Parking
No additional off-street parking required for the ADU
Rental license
A separate St. Paul rental license is required for each unit before placing tenants
Historic districts
Properties in the Hill District or on Summit Avenue require additional design review
Building code
Must meet 2020 Minnesota Residential Code standards
Ordinance history
How St. Paul's ADU rules got here
2016ADUs first allowed in a limited geographic area of the city, as a pilot.
2018Citywide allowance. Council extended ADUs to all residential districts, but kept an owner-occupancy requirement and a minimum lot size that made many parcels ineligible - only a handful of units were actually built under this version of the rule.
2022Two big barriers removed. The owner-occupancy requirement and the detached-ADU minimum lot size were both eliminated.
2023Ordinance 23-43. Raised the size cap to 800 sq ft or 75% of the principal dwelling (whichever is greater), allowed up to 2 ADUs per lot, and set a flat 25 ft height limit regardless of the main house's height - the most significant liberalization to date.
Worth knowing: a 2021 review found only about a dozen ADUs had actually been built under the original 2018 ordinance, mostly held back by the owner-occupancy rule and lot-size minimum. Both barriers are gone now, which is why St. Paul currently scores as one of the more workable ordinances in the metro.
Permit process
How St. Paul ADU permitting works
1
Confirm zoning
Check your property's zoning district and whether historic design review applies (Hill District / Summit Avenue).
2
Get a certified survey
DSI requires a certified signed survey of the lot before it will review your building permit application.
3
Prepare your plan set
You'll need ADU floor plans and elevations, civil plans showing utility connections, and floor plans of the existing house to verify the size-limit math.
4
Submit the building permit application
Include a site plan showing setbacks and the ADU's relationship to the principal dwelling.
5
Plan review & inspections
Standard review typically takes 2 to 4 weeks; historic districts add roughly 4 to 8 weeks for design review. Once permitted, expect the usual framing, plumbing, electrical, and final inspections.
6
Rental license (if renting)
Apply for a separate rental license for each unit before placing tenants.
Timelines are approximate and vary by application completeness and whether design review is required - confirm current figures with DSI at 651-266-8989 (weekdays, 7:30 a.m. to 4:30 p.m.).
Budgeting
What it costs to build an ADU in St. Paul
Garage conversion
Roughly $65,000-$155,000, the least expensive path since the shell already exists
Basement conversion
Roughly $110,000-$220,000, depending on existing ceiling height and utility access
New detached ADU
Roughly $135,000-$270,000+ for a code-compliant, fully insulated freestanding unit
SAC fee
$2,485 per unit in 2026, charged by Metropolitan Council Environmental Services on new units that add sewer demand
City permit & plan review fees
Set by DSI's valuation-based fee schedule - get a project-specific quote before you budget
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and whether utilities need to be extended. Minnesota's climate adds real cost too: a detached ADU is a fully insulated, freestanding structure, not just a room.
Before you apply
Tips for a smooth approval
Order your survey early. DSI won't review your building permit without a certified signed survey, and surveyors can book out several weeks.
Check historic district status before you design. Hill District and Summit Avenue properties go through extra design review that can add 4-8 weeks - better to know upfront than mid-permit.
Budget for SAC and rental licensing, not just construction. The $2,485 SAC fee and rental license costs are easy to forget when comparing contractor bids.
Use the current size formula, not an old one. Some contractors and templates still reference St. Paul's pre-2023 800 sq ft flat cap - you're now allowed 75% of the main house's floor area if that's larger.
Decide on rental plans before you build. If you'll rent either unit, you'll need a separate rental license per unit - it's easier to plan the layout with that in mind from the start.
FAQ
Common questions
Do I need to live on the property to have an ADU in St. Paul?
No. Ordinance 23-43 (2023) eliminated the owner-occupancy requirement - you can rent both the main house and the ADU without living on site, provided each is properly rental-licensed.
How many ADUs can I build?
Up to two ADUs are allowed on a single-family lot, in addition to the principal dwelling.
Is there a minimum lot size?
No - St. Paul eliminated minimum lot size requirements for ADUs under the 2023 reform.
What if my property is in a historic district?
Homes in the Hill District or on Summit Avenue go through additional design review, which typically adds 4–8 weeks to the process.
Do I need a rental license?
Yes - if you rent out your ADU (or your main house) you need a separate St. Paul rental license for each unit.
How much does an ADU cost to build in St. Paul?
It depends heavily on the type of project. Garage conversions tend to run roughly $65,000-$155,000, basement conversions $110,000-$220,000, and new detached units $135,000-$270,000 or more, based on local contractor estimates and regional reporting - not counting the $2,485 SAC fee and permit costs.
What documents do I need for the building permit?
DSI asks for a certified signed survey, civil plans showing utility connections, floor plans and elevations of the ADU, and floor plans of the existing house so staff can confirm the size-limit calculation.
What's the SAC fee, and do I always have to pay it?
SAC (Sewer Availability Charge) is a regional fee charged by the Metropolitan Council on units that add new sewer capacity demand - $2,485 per unit in 2026. Whether it applies to your project depends on the specifics; confirm with DSI before you budget.
Can I rent my ADU out on Airbnb or a short-term rental platform?
St. Paul regulates short-term rentals separately from standard rental licensing, with its own registration requirements and limits. If that's the plan, confirm current short-term rental rules with the city before you finalize your design.
