You can convert a single-family dwelling to a duplex in Minneapolis.
Property owners who want to convert a single-family dwelling to a duplex must:
- Learn City of Minneapolis and State of Minnesota dwelling rules
- Create a floor plan
- Complete a building permit application
- Get zoning and plan review approval
Step 1: Learn City of Minneapolis and State of Minnesota dwelling rules
Each dwelling unit must have at least one side-hinged door that is a minimum of 32” clear width and 78” clear height.
- Each dwelling unit must have at least one habitable room with at least 120 square feet of gross floor area.
- Other habitable rooms must have a floor area of not less than 70 square feet, except kitchens.
- No habitable rooms can be less than 7 feet in width, except kitchens.
- Rooms exclusively for sleeping must have a minimum of:
- 70 sq. ft. for one person
- 90 sq. ft for two persons
- 50 sq. ft for each additional person (maximum of four)
- Efficiency units must have a living room of not less than 350 square feet of gross floor area (535.90)
Arrangement of rooms
An occupant of a dwelling unit cannot be required to pass through any bedrooms or bathrooms to get to their bedroom or bathroom, or to any other room in the unit.
Habitable spaces including kitchens, baths, halls, laundry rooms, shall have ceiling heights of a minimum of 7'-0".
- Sloped ceilings: For rooms with sloped ceilings, the 7’-0” dimension must be at least 50% of the floor area. The floor area is measured from where the ceiling is at least 5’-0” high.
- Bathrooms: Ceiling height of 6’-8”minimum is required at the center of the front of toilets and sinks. At showers or tubs equipped with a shower head, the ceiling height of 6’-8 “is required for an area 30" x 30" at the shower head.
- Basements: The minimum ceiling height in existing basements shall be 6’-4”. Measurement to be the clear dimension between the finished floor surface and ceiling finish. No beam, girder, duct, pipe, soffit or other obstruction may project below 6’-4”.
Light, ventilation and heating
- Heating facilities must be capable of maintaining a minimum room temperature of 68 degrees F at a point three feet above the floor and two feet from exterior walls in all habitable rooms.
- Fuel-fired appliances must not be located in or obtain combustion air from sleeping rooms, bathrooms or closets.
- Air circulation is not permitted between dwelling units. Where forced air heating units are provided, separate units are required for each dwelling.
- Operable windows must be provided in all habitable spaces and bathrooms unless both of the following are provided:
- A mechanical ventilation system capable of providing 0.35 air change per hour in the room or a whole-house mechanical ventilation system is installed capable of supplying outdoor ventilation air of 15 cubic feet per minute per occupant on the basis of two occupants for the first bedroom and one occupant per each additional bedroom.
- Artificial light capable of producing an average illumination of six foot-candles over the area of the room at a height of 30 inches above the floor level.
Dwelling units in two-family dwellings shall be separated from each other by wall or floor assemblies having not less than one-hour fire-resistance rating when tested in accordance with ASTM E 119.
- New construction or removal of existing plaster or wallboard requires installation of an approved design and assembly.
- Existing walls and floor‑ceiling assemblies which are intact and are to remain in place. The following are permitted:
- Floor‑ceiling: Install resilient channels at 24” o.c. max and a one (1) layer of 5/8" Type "X" (or 1/2” Type “C”) gypsum board.
- Walls: Install resilient channels at 24" o.c. max. and one (1) layer of 5/8" Type "X" (or 1/2” Type “C”) gypsum wallboard, on one side. On opposite side, install one layer 5/8" gypsum (or 1/2” Type “C”) wallboard directly to existing wall surface.
- Wall at stair: Where wall separates unit from a stair Install resilient channels at 24” o.c. max and a one (1) layer of 5/8" Type "X" (or 1/2” Type “C”) gypsum board to the dwelling unit side of wall.
Walls and floor‑ceiling assemblies separating dwelling units from each other and common areas such as stairway, corridors, dwelling unit entrance doors, etc. shall meet Airborne Sound Transmission Class (STC) rating of STC 45 when tested in accordance with ASTM E 90.
Note: Penetrations or openings in construction assemblies for piping; electrical devices; recessed cabinets; bathtubs; soffits; or heating, ventilating, or exhaust ducts shall be sealed, lined, insulated or otherwise treated to maintain the required ratings.
Floor-ceiling assemblies between dwelling units or between a dwelling unit and a public or service area within a structure shall have an Impact Insulation Class (IIC) rating of not less 45 when tested in accordance with ASTM E492.
You must get electrical permits through the Minnesota Department of Labor and Industry. All requirements should be verified with the appropriate inspector.
Electrical Panels (NFPA 70: Article 230.72 + 240.24): Each occupant shall have ready access to the panel that supplies that dwelling. Panels shall not be located where they may be exposed to damage, in a bathroom, over steps or stairs or in a closet.
- Egress windows: required in all sleeping rooms.
See Minnesota Residential Building Code
- Smoke and carbon monoxide detectors: required.
See Smoke and Carbon Monoxide Alarm bulletin
See constructing or removing a stairway
Step 2: Create a floor plan
Create a floor plan for your project drawn to scale. (You will submit the floor plan in digital (PDF) format shortly after you apply for the permit.)
Your floor plan must:
- Show the layout of the dwelling along with any proposed changes
- Include each level of the home, such as the:
- Main floor
- Second floor
- Show all the following:
- An outline of the foundation walls
- An outline of the interior and exterior walls
- The location of windows, doors and stairways
- Identify the rooms by name, such as:
- Living room
- Dining room
- Kitchen (include arrangement of cabinets, stoves, sink, refrigerator)
- List room dimensions (you can use a simple description, such as 12 X 10 feet)
Your floor plans must also show any planned construction work, such as the location where:
- New walls will be built
- Old walls will be removed
- You will make changes to doors, windows or floor openings
- Kitchens will be added
We recommend but do not require you to:
- Use a scale of 1/4” per foot
- Draw a before and after set of floor plans
We don’t require that you use an architect to draw floor plans. If you have trouble creating accurate plans, however, you may want to get help from one of the following:
- An architect
- A contractor
- A drafting service
Step 3: Complete a building permit application
After you have finished your floor plan, the next step is to complete a building permit application. The person doing the work is the permit applicant:
- If you, as the owner-occupant, will be doing the work, you would be the permit applicant.
- If you hire a contractor, the licensed contractor would be the permit applicant.
If you, as the owner-occupant, will do any plumbing, electrical or mechanical work, you must also apply for those permits.
After you submit the building permit
- You will receive an email from a City development coordinator.
- The development coordinator will explain the process to submit your floor plans using the City’s ProjectDox electronic plan system. (Note: Due to COVID-19, you must submit plans online. We may accept paper plans in the future.)
- After you submit the floor plans, City staff will do a zoning and plan review.
Step 4: Get zoning and plan review approval
When a property owner wants to change the use of a building, the City must do a zoning and plan review to approve the floor plan.
Staff people from two divisions in the City’s Community Planning & Economic Development (CPED) department will review your plan:
- CPED Zoning will verify that converting from a single-family dwelling to a duplex complies with the City Zoning Ordinance.
- CPED Construction Code Services will review for state building code requirements.
During the review, CPED might send you comments for correction. If this happens, you will need to correct the floor plan and resubmit it.
Once CPED approves your plans
- We will issue a building permit to officially convert the building to a duplex.
- You will be notified by our electronic system to pay for the permit.
After you finish the building project
After you finish the project, the City will inspect the new dwelling. Once CPED approves your work, we will:
- Update the certificate of occupancy to a duplex.
- Change the unit count record to 2 in department permit records.
- Notify the City’s Solid Waste & Recycling and Utility Billing (water department) that the conversion is complete. City services will then be billed for a duplex.