Can you build an ADU in St. Paul, MN?
ADUs are expressly allowed in multiple districts when tied to a one-family dwelling, and the city has reduced barriers by removing owner-occupancy and allowing up to two ADUs per one-family dwelling.
Confidence: high · Last researched May 2026
ADU rules
ADUs are secondary dwelling units associated with a principal one-family dwelling and may be within, attached to, or detached from that dwelling on the same zoning lot.
- ADUs are only permitted when there is an associated one-family dwelling on the same lot.
- Two ADUs are permitted for each one-family dwelling on a lot.
- If there are two ADUs for one-family dwelling, at least one of the ADUs must be detached from the one-family dwelling.
- Exception: both ADUs may be attached if at least 50% of the floor area of an existing principal residential structure on the zoning lot is retained.
- Combined occupancy of the one-family dwelling and associated ADUs cannot exceed the occupancy allowed under the definition of Household.
- Maximum floor area of each accessory unit is 800 square feet or 75% of the floor area of the associated principal dwelling unit, whichever is greater.
- Detached ADUs may be up to 25’ in height regardless of the height of the principal dwelling.
Dimensional standards in St. Paul, MN
| RL — minimum lot area | 21,780 square feet — Larger lot may be required depending on sewage treatment system needs. |
| RL — minimum front setback | 30 feet — May be adjusted by blockface averaging rule where at least 50 percent of front footage is built up with principal structures. |
| RL — minimum side setback | 10 feet |
| RL — minimum rear setback | 25 feet |
| R1 — minimum lot area | 9,600 square feet — Where over half of the lot has slopes of twelve percent or greater, minimum lot size shall be 15,000 square feet. |
| R1 — minimum front setback | 30 feet — May be adjusted by blockface averaging rule. |
| R1 — minimum side setback | 10 feet |
| R1 — minimum rear setback | 25 feet |
| R2 — minimum lot area | 7,200 square feet |
| R2 — minimum front setback | 25 feet — May be adjusted by blockface averaging rule. |
| R2 — minimum side setback | 8 feet |
| R2 — minimum rear setback | 25 feet |
| R3 — minimum lot area | 6,000 square feet |
| R3 — minimum front setback | 25 feet — May be adjusted by blockface averaging rule. |
| R3 — minimum side setback | 6 feet |
| R3 — minimum rear setback | 25 feet |
| R4 — minimum lot area | 5,000 square feet — These standards apply when one-family dwellings are erected in less restrictive residential districts. |
| R4 — minimum front setback | 25 feet — May be adjusted by blockface averaging rule. |
| R4 — minimum side setback | 4 feet |
| R4 — minimum rear setback | 25 feet |
| RT1 — minimum lot area | 3,000 square feet — RT1 standards apply when two-family dwellings are erected in less restrictive residential districts. |
| RT1 — minimum front setback | 25 feet — May be adjusted by blockface averaging rule. |
| RT1 — minimum side setback | 9 feet |
| RT1 — minimum rear setback | 25 feet |
| RT2 — minimum lot area | 2,500 square feet — Applies to entire parcel where townhouse lots are individually described with common land. |
| RT2 — minimum front setback | 25 feet — May be adjusted by blockface averaging rule. |
| RT2 — minimum side setback | 9 feet |
| RT2 — minimum rear setback | 25 feet |
| RM1 — minimum lot area per unit | 2,000 square feet — No multifamily dwelling with three or more units on a lot less than 9,000 square feet. |
| RM1 — minimum front setback | 25 feet — May be adjusted by blockface averaging rule. |
Related questions
Are ADUs allowed in St. Paul, MN?
ADUs are secondary dwelling units associated with a principal one-family dwelling and may be within, attached to, or detached from that dwelling on the same zoning lot.
Full investor analysis
You've seen the general rule. The full St. Paul, MN report shows which districts allow ADUs by-right vs. by special permit, the approval path and timeline, and the overlay/flood constraints that quietly kill ADU projects here. First town report is free.
Get the full St. Paul, MN report free →More about St. Paul, MN zoning
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This summary is AI-generated from public municipal sources and is not legal, engineering, or land-use advice. Always verify zoning with St. Paul, MN officials before making decisions.
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