Saint Paul, MN Accessory Structures: ADU Rules (2026)

913 defines an accessory dwelling unit as secondary housing within, attached to, or detached from a one-family dwelling on the same zoning lot, and sets six standards for it. A property can have up to two accessory dwelling units; if there are two, at least one must be detached unless the project retains at least 50 percent of the floor area of an existing principal residential structure, in which case both may be attached. 209. Each accessory unit's total floor area is capped at 800 square feet or 75 percent of the principal dwelling's floor area, whichever is greater.

A walkway must connect an abutting public street to the accessory unit's primary entrance; upper-floor units within the principal structure need interior stairway access, though exterior stairways required for fire safety can go on the side or rear (never the front) and must be built of durable material matching the principal structure's finish: raw or unfinished lumber is not allowed. Accessory dwelling units can never be sold separately from the principal dwelling or platted as their own tax parcel. 501(d). The section was most recently amended by Ordinance 23-43 on October 18, 2023.