South Portland, Maine

South Portland, ME Accessory Dwelling Unit (ADU) Rules

City Acceptance Rating: 7/10

Last Updated: 7.2.2024

Image source: MaineBiz

What You Need to Know

ADUs in South Portland can be with an existing dwelling, attached to an existing dwelling, detached from the existing dwelling.  There are a number of design considerations that must be taken into account when designing and building an ADU.

Type of Permit Required

ADUs are permitted through the Code Enforcement Officer.

ADU Rules

• Size conditions:

1. For lots under 10,980 square feet, ADUs shall not be greater than 800 square feet or 90% of the principal dwelling, whichever is less.

2. For lots 10,890 square feet or above, ADUs shall not exceed 10% of the parcel area, 1,200 square feet or 90% of the principal dwelling, whichever is less.

3. No ADU can be less than 190 square feet of living area.

4. On properties with two or three dwelling units, the ADU cannot be greater than 90% of the largest legal unit.

5. The ground floor coverage created from the ADU is limited to 800 square feet.

• Ownership

1. The ADU and the primary dwelling must remain in common ownership.

2. The owner of the property must reside in either the primary dwelling or the ADU.

• Design Considerations:

1. The ADUs primary entrance cannot be the same as the primary dwelling and must be less visible from the street

2. There must be a clear relationship between the rooflines of the ADU and the primary dwelling.

3. The placement of the ADU must maintain the privacy of the residents of the primary dwelling.

4. The max height of a detached ADU must not exceed 28 feet.

5. A safe pathway must be created from the ADU to the closest public sidewalk.

6. No additional parking spaces are required for the addition of an ADU

• Uses

1. ADUs cannot be used as short-term rentals.

Resources:

South Portland Zoning Code- Section 27/Article 15/Page 91

https://www.southportland.org/DocumentCenter/View/1510/CH-27--Zoning-with-New-TOC-format