Lewiston, Maine
Lewiston, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last updated: 6.24.2024
Image source: City of Lewiston
What You Need to Know
Lewiston changed its zoning ordinance in April, 2023 to allow for ADUs to be built with a building permit. ADUs are allowed on land where single family detached dwellings or mobile homes are located.
Type of ADU Permit Required
ADUs are permitted by right in Lewiston.
ADU Rules in Lewiston
ADUs may be attached or detached from the primary dwelling.
ADUs must be on the same parcel and be built on permanent foundations.
When an ADU is attached, the principal dwelling must have the only main entrance, and other entrances must appear subordinate.
No additional curb cuts are allowed, and the ADU must share the same driveway as the principal residence. Driveways may not be expanded to exceed 24 feet in width.
ADUs may not be greater than 900 square feet and are limited to two bedrooms. ADUs may not be less than 190 square feet.
Detached ADUs must be located to the side or rear of the primary dwelling.
The ADU or the primary dwelling must be occupied by the owner.
No additional parking is required for the ADU.
The ADU is subject to all fire safety and egress requirements.
ADUs on properties with private sewer must meet requirements for new or expanded systems.
The primary dwelling and ADU must remain under common ownership.
Resources:
City of Lewiston Zoning and Land Use Code Section 11/Page 59
https://www.lewistonmaine.gov/DocumentCenter/View/250/Article-XII?bidId=
Belfast, Maine
Belfast, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 6.24.2024
What You Need To Know
Both attached and detached ADUs are allowed in Belfast.
Type of ADU Permit Required
A building permit is required in Belfast for ADUs.
ADU Rules
ADUs are limited to a two bedroom maximum and are limited to 800 square feet or 75% of the square footage, whichever is less.
An ADU within a detached accessory structure is still limited to no greater than 800 square feet.
A structure of this type is limited to attached open structures, such as a deck, that are no more than 200 square feet.
Adequate capacity for sewer must be provided.
There can only be one two way driveway or two one way driveways, but there cannot be separate driveways for the principal dwelling and ADU.
If the home is on a road with a posted speed limit of 40 mph or greater, a turnaround must be constructed.
Resources:
https://www.cityofbelfast.org/DocumentCenter/View/5693/Draft-Chap-102-ADU-Standards?bidId=
Kittery, Maine
Kittery, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated 6.24.2024
Image source: Foster’s Daily Democrat
What You Need To Know
ADUs are allowed in Kittery in all residential zoning districts. ADUs built within an existing structure, attached, or detached are all permitted.
Type of ADU Permit Required
ADUs are permitted via the Code Enforcement Officer.
ADU Rules
ADUs are only allowed on lots where there is one single family dwelling
ADUs are limited to one per lot.
ADUs may not be greater than 1,000 square feet.
For single family homes 1,000 square feet or less, the ADU may not be greater than 80% of the square footage of the single family dwelling.
ADUs are exempt from density requirements.
For conforming lots, ADUs must meet yard setbacks; however, for legally nonconforming lots that cannot meet setback requirements, the percentage of how much smaller the lot is will determine the setback requirements.
All utilities must meet or be updated to provide adequate service to the ADU.
One parking space must be provided for the ADU in addition to the parking available for the existing single family dwelling.
If an ADU is to be located on a privately maintained road or right-of-way, written permission must be obtained from the homeowner’s association and individuals/groups responsible for street maintenance.
Rental periods may not be less than 30 days.
Resources:
Town of Kittery Land Use Zone Regulations
https://ecode360.com/15062383
York, Maine
York, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 6.25.2024
Image source: Wikipedia
What You Need To Know
ADU regulations have loosened in York. This includes capacity for a larger ADU, and they no longer require a special exception.
Type of ADU Permit Required
An ADU in York requires a building permit issued by the Code Enforcement Officer.
ADU Rules
Only one ADU is allowed per lot.
Short term rentals are not permitted in the ADU, principal dwelling, or on a lot where an ADU is constructed.
The property owner must reside in either the ADU or the primary dwelling during a portion of each calendar year.
The gross floor area of the ADU may not exceed 50% of the total gross floor area of the primary dwelling or 850 square feet, whichever is less.
Gross floor area does not include garage or unfinished attic space.
The minimum gross floor area is 190 square feet.
A home business or occupation can be conducted in either the ADU or primary dwelling but not both.
ADUs must be designed to maintain the character of the primary dwelling.
Exterior stairs are not allowed.
If the ADU is detached, it must be designed in the style of a barn, garage, carriage house, or similar structure usually located on a single family lot.
Wherever realistic, no more than one curb cut is allowed, unless the lot has multiple curb cuts already.
If the existing dwelling is on a well, a test must be completed and reported to the Code Enforcement Officer.
Detached ADUs must be no further than 150 feet from the primary dwelling.
Resources:
Town of York, Maine Zoning Ordinance Article 7.17/Page 139
https://www.yorkmaine.org/DocumentCenter/View/11468/Zoning-Ordinance_2024-5-18_Certified
Kennebunkport, Maine
Kennebunkport, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 6.26.2024
Image source: The Beach House Inn
What You Need To Know
Kennebunkport updated their ADU bylaws in 2023 to allow for ADUs in all zones except for a few exceptions.
Type of ADU Permit Required
ADUs are permitted through submission of a site plan that includes lot boundaries, dimensions to scale, and location and setbacks of all buildings and parking areas. Additionally, for the ADU, a plan of the entire building that shows the floor layout of all finished levels, use of each room, and location of all entrances and exits is required.
ADU Rules
Only one ADU is permitted per single family dwelling.
ADUs may be located within a dwelling, attached to an existing dwelling, or detached.
The primary dwelling may only have one front entrance; however, a foyer may be created that leads from the foyer to the two dwellings.
ADUs are not permitted in Shoreland zoning unless the lot is double the lot size for that zone, double the minimum lot size, and double the shore frontage.
The ADU cannot operate as a short-term rental and must be rented for a period of six months or greater.
Town sewer or septic systems must be evaluated to ensure capacity and proper condition.
Properties on private wells must have a water quality test done prior to receiving a certificate of occupancy.
Resources:
Kennebunk Zoning Ordinance- Section 15/Article 10/Page 54
https://www.kennebunkmaine.us/DocumentCenter/View/9827/ARTICLE-10-w-2020-7-14-updates?bidId=
Kennebunk, Maine
Kennebunk, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 6.28.2024
What You Need To Know
Kennebunkport updated their ADU bylaws in 2023 to allow for ADUs in all zones except for a few exceptions.
Type of ADU Permit Required
ADUs are permitted through submission of a site plan that includes lot boundaries, dimensions to scale, and location and setbacks of all buildings and parking areas. Additionally, for the ADU, a plan of the entire building that shows the floor layout of all finished levels, use of each room, and location of all entrances and exits is required.
ADU Rules
Either the ADU or the primary dwelling must be occupied by the property owner as their primary residence.
The ADU and the primary dwelling must be occupied as an individuals’ primary residence.
Only one ADU is permitted per single family lot.
ADUs are limited in square footage to a minimum of 190 square feet and a maximum of 1,000 square feet.
If located in the shoreland zone, ADUs must separately meet the space and bulk requirements.
ADUs cannot be used as short term rentals, and only one unit ,either the primary dwelling or the ADU, can be rented.
Resources:
Kennebunk Zoning Ordinance- Section 15/Article 10/Page 54
https://www.kennebunkmaine.us/DocumentCenter/View/9827/ARTICLE-10-w-2020-7-14-updates?bidId=
Freeport, Maine
Freeport, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10 (10 is most accepting)
Last updated: 8.6..2024
What You Need To Know
Freeport broadened their rules and streamlined their process to allow for ADUs on all lots in which single family or duplex dwellings exist. One ADU is allowed per single family dwelling, and up to two ADUs can be constructed.
Type of ADU Permit Required
ADUs are permitted by right in Freeport and require a building permit.
ADU Rules
Only one ADU permitted is allowed on any lot containing either one or two existing or proposed single family homes or one duplex.
ADUS can be created in one of the following ways:
Using space within an existing single family home or a duplex.
Building an addition onto an existing single family home or duplex.
Use space in an existing accessory structure (not a shed) that is legally existing on or prior to January 1st, 2024.
Detached ADUs built in a structure built on or prior to January 1st, 2024 must adhere to the minimum setback requirements for single family homes and duplexes.
The ADU cannot be greater than 75% of the gross floor area of the largest existing new or single-family dwelling or largest unit in an existing or new Duplex or 1,100 square feet, whichever is lesser.
Any alterations to accommodate an ADU shall maintain the front entrance and residential character of the existing dwelling. Any additional entrance must appear secondary to the main entrance.
No additional parking is required for the ADU.
Water and wastewater requirements must be met.
Resources:
Saco, Maine
Saco, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 6.10.2024
What You Need To Know
ADUs in Saco are intended to increase affordable housing supply, encourage varied household types, encourage development of existing spaces that maintain the character of the town, and utilities existing utility infrastructure.
Type of ADU Permit Required
ADUs require a building permit in Saco.
ADU Rules
ADUs can be within, attached, or detached and only one ADU is permitted per lot.
ADUS are limited to a maximum of 1,000 square feet and a minimum of 400 square feet.
ADUs square footage is not considered when calculating minimum lot coverage.
ADUs cannot be rented for a period of less than one month.
ADUS must be constructed on permanent foundations.
If public sewer and water services the lot, the ADU and primary residence must be hooked up to public sewer and water.
Detached ADUs
Must have a sprinkler or fire suppression system installed
If constructed attached or within a dwelling, sprinkler or fire suppression systems are only required if they are already installed in the existing dwelling.
Must share the existing driveway of the primary dwelling
Must be designed compatibility to the primary dwelling
Must share the existing driveway.
Resources:
Biddeford, Maine
Biddeford, Maine has excellent rules for accessory dwelling units with few restrictions.
Biddeford, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 6.28.2024
What You Need To Know
Biddeford allows ADUs with the intention of providing residents with rental income, add moderately priced units, and develop housing units in single family neighborhoods.
Type of ADU Permit Required
The unit is permitted through the Code Enforcement Officer.
ADU Rules
Only one ADU is permitted per parcel.
ADUs must remain in common ownership with the primary dwelling
ADUs cannot be less than 300 square feet.
The gross floor area cannot be greater than 35% of the primary dwelling or 900 square feet, whichever is greater.
The ADU once in place cannot increase in gross floor area beyond the regulation above.
Rooftop decks are not allowed.
Balconies cannot face interior side lot lines.
One off-street parking space is required for the ADU unless legal on-street parking or publicly supplied off-street parking is located within 1,000 feet.
ADUs within
Construction of an ADU within a dwelling cannot result in additional entrances that face the public street.
All stairways leading to the ADU must be internal.
ADUs attached
An ADU attached cannot result in additional entrances that face the public street.
All stairways leading to the ADU must be internal.
The primary exterior materials must match the primary exterior materials of the principal structure.
Detached ADUs
Not less than 10% of the total area of the facade of the detached ADU facing an alley or public street may have windows.
Exterior stairways are allowed as long as they are finished in a way that matches the finish or trim of the detached ADU.
The ADU or the primary dwelling must be the residence of the owner of the property.
No more than three people can live in an ADU.
Resources:
https://www.biddefordmaine.org/3127/Accessory-Dwelling-Units-ADUs
Portland, Maine
Portland Maine allows two ADUs on any residential property! A single ADU can be up to 2/3 the size of the primary dwelling unit, or the size of two ADU can be equal to the size of the primary dwelling.
After updating its ADU rules in 2021, Portland has one of the most lenient ADU rules in New England. The rules provide great opportunities to add housing for families or generate rental income in Portland's booming rental market.
Portland, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 11.14.2024
Image source: Town of Cape Elizabeth
What You Need To Know
ADUs are permitted in Portland on all legal lots, and on qualifying lots, you can build up to two ADUs.
Type of ADU Permit Required
ADUs are permitted by right through the building department.
ADU Rules
Permitted Locations: ADUs allowed on lawfully conforming and nonconforming lots with legal residential uses.
Types of ADUs: Can be new detached structures, building additions, or within existing structures. Nonconformities cannot increase unless specifically permitted.
Number of Units: Up to two ADUs allowed per qualifying property.
Design Considerations: ADUs in nonconforming structures must prioritize adjacent property privacy.
Size Restrictions:
ADU floor area limited to 2/3 of the largest principal unit's gross floor area.
Total detached ADU square footage cannot exceed the principal structure's gross floor area.
Lot Requirements: Exempt from maximum lot coverage and minimum lot area per dwelling unit requirements.
Height Limits: Detached ADUs limited to 18 feet in height or 25 feet if above a garage.
Setbacks: Subject to side and rear setbacks for accessory structures under 250 square feet.
Placement: Detached ADUs prohibited between the principal structure and front lot line.
Resources:
https://static1.squarespace.com/static/5a75f43a692ebeeb1159413d/t/671025bbe5595f4d699c1994/1729111486146/Final+draft+LUC_10_8_24_compressed_reduced.pdf - pages 91-92 of PDF
Scarborough, Maine
Scarborough, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
Last Updated: 7.2.2024
Image source: Green Healthy Maine
What You Need To Know
ADUs are permitted within, attached, or detached in Scarborough.
Type of ADU Permit Required
ADUs in Scarborough are permitted through the Code Enforcement Officer..
ADU Rules
Only one ADU is permitted per lot.
The owner of the ADU must live in either the primary dwelling or the ADU.
Neither the primary dwelling or ADU can be rented for a period of less than 28 days.
Only two individuals may live in the ADU.
The ADU is limited to 190 square feet or:
If the living space of the single family dwelling is:
Up to 2,000 SF- The living space of the accessory unit shall not exceed 40% or 750 SF, whichever is greater.
2,000 SF to 3,000 SF- The living space of the accessory unit shall not exceed 35% or 750 SF, whichever is greater.
3,000 SF to 5,000 SF- The living space of the accessory unit shall not exceed 30% or 1,050 SF, whichever is greater.
5,000 SF or over- The living space of the accessory unit shall not exceed 20% or 1,500 SF, whichever is greater.
ADUs are exempt from density or lot area requirements as it relates to the area in which an ADU is constructed, but must meet dimensional or setback requirements.
ADUs are permitted within, attached or detached.
ADUs are allowed on nonconforming lots, but the ADU or structure in which it is located must meet dimensional requirements.
Ingress and egress must be available to the ADU.
The design of an attached or ADU within a primary dwelling must be designed with the character of the area and preservation of the appearance of a single family home in mind.
Exterior stairs are not permitted.
For ADUs within or attached to a primary dwelling, single family dwelling setbacks and dimensional requirements must be followed.
ADUs detached from the primary dwelling cannot be built further than 100 feet from the nearest point of the primary dwelling and must be designed in the style of a barn, storage, building, garage, carriage, house, accessory cottage, or similar structure that you would find on the same lot as a single family residence.
ADUs and the corresponding primary dwelling must be serviced by the same utility meters unless the utility company refuses to do so.
If a utility company refuses, the applicant must provide a letter to the code enforcement officer indicating the reason for their refusal.
For lots that are not connected to public sewer, documentation must be provided that the lot meets the state’s minimum requirements as well as Maine’s plumbing code and Scarborough’s.
The owner of the ADU must provide written confirmation that each unit on the property has adequate water and wastewater services prior to certification of occupancy being given. The written confirmation must include the following:
Proof of adequate service if connected to public sewer
If on septic, proof of adequate sewage disposal and verification through local plumbing inspector
If on a well, must provide proof of potable water
Resources:
Zoning Ordinance Town of Scarborough- Section 5/Page 24
Falmouth, Maine
Falmouth, Maine Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 10/10
last updated 4/13/2020
What you need to know about Falmouth
In 2016 Falmouth, ME revised its Accessory Dwelling Unit (ADU) rules making all types of ADUs allowed by right. This means homeowners can build a 2nd small home on their property without applying for a special permit which saves time, aggravation, and money.
These attractive ADU rules give homeowners the ability to sell their backyard, create space for family, or even build a small home to rent out and generate rental income.
Opportunities in Falmouth, Me:
Sell your un-subdividable backyard
Build a small home to rent out
Create space for family
Type of Permit Required:
ADUs are allowed by right. Homeowners only need to apply for a building permit to build an ADU/small home in their backyard.
Other ADU Rules in Falmouth:
ADUs are allowed by right in all residential zoning districts
The ADUs living area cannot exceed that of the existing house or 850SF, whichever is larger
The ADU and primary house can only have one main entrance. Other entrances must be designed to appear subordinate
Download Falmouth’s full zoning bylaw
Download the Accessory Dwelling Unit rules section
Download lot size and setback requirements.