Wells, Maine
Wells, ME Accessory Dwelling Unit (ADU) Rules
Last Updated: 11/17/2025
Image source: Town of Wells Facebook
What You Need to Know
Wells changed their zoning rules in 2025 to allow an easier pathway for building ADUs. The new rules for Wells are outlined below.
Type of Permit Required
ADUs in Wells do not require special permits, and can be built using a traditional building permit. Residents are allowed to build one ADU per lot, regardless of if it’s a single-family, duplex or multi-family lot.
ADU Rules in Wells
ADUs can be a maximum of 800 square feet.
Detached ADUs cannot be less than 400 square feet.
Attached ADUs can be at minimum 190 square feet, and no more than 35% of the area of the main house.
ADUs cannot have more than three rooms and a bathroom.
ADUs may be attached, detached, or built within the main house.
Short term rentals are not allowed - the main house or the ADU can be rented with a minimum lease term of 12 months.
ADUs in Wells do not need additional parking.
Attached ADUs must maintain the architectural style of the main house.
The main house and ADU must be owned by the same person(s).
The property owner(s) must live either in the main house or the ADU.
Resources:
Bridgton, Maine
Bridgton, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10
Last Updated: 11.8.2024
Image source: Town of Bridgton
What You Need to Know
One ADU is allowed per single-family, two-family, or multi-family dwelling, and it must comply with size regulations, including a minimum footprint of 190 square feet and a maximum footprint of 1,000 square feet or 50% of the primary dwelling's footprint. ADUs can be constructed within the primary dwelling, in an accessory structure, or as a separate structure on the lot. Additionally, ADUs must adhere to all other zoning requirements, including those related to Shoreland Zoning.
Type of Permit Required
ADUs are allowed by right and require a building permit through the Code Enforcement Officer in Bridgton.
ADU Rules
Size & Floor Area:
Minimum floor area of 190 square feet.
Maximum floor area of 1,000 square feet or 50% of the primary dwelling's floor area, whichever is smaller.
ADU cannot have more than two bedrooms.
Floor area excludes unfinished attic, basement, or cellar spaces.
Floor area is measured from the interior faces of the walls.
Location & Setbacks:
Detached ADUs must meet the same setbacks as the principal residential structure and cannot exceed the height of the primary dwelling.
ADUs within the same structure or attached to the primary dwelling must meet the dimensional requirements for the district.
ADUs cannot be constructed in existing detached accessory structures.
ADUs outside of shoreland zones are not considered additional dwelling units for lot area or residential density calculations.
Parking Requirements:
No additional parking required for ADUs under 600 square feet, though additional parking should be provided as needed.
ADUs over 600 square feet must provide two additional off-street parking spaces.
Off-street parking spaces cannot be eliminated to convert an attached garage into an ADU.
Utilities:
If connected to public sewer, both the ADU and primary dwelling must be connected, with proof of adequate service.
If using a septic system, the system must meet Maine’s Minimum Lot Size law and state rules for subsurface wastewater disposal.
If connected to public water, proof of adequate service is required. If using a well, proof of potable water is needed.General Rules:
An ADU is not considered a dwelling unit for the purpose of calculating lot size or road frontage requirements, nor when applying the subdivision definition, if it complies with the standards in subsection K.
ADUs that do not meet these standards are considered dwelling units and must comply with all dwelling unit standards.
Location and Eligibility:
No ADU is allowed on a lot without a single-family, two-family, or multi-family dwelling.
One ADU is allowed per single-family, two-family, or multi-family dwelling.
Construction:
ADUs can be located within or attached to the primary dwelling, in an accessory structure, or as a separate structure on the lot.
Size and Design:
Minimum footprint of 190 square feet.
Maximum footprint is the lesser of:
50% of the footprint of the largest dwelling on the property (single-family or the largest unit of a two-family or multi-family dwelling), or
1,000 square feet.
ADUs cannot have more than two stories.
Compliance:
ADUs must comply with all other applicable regulations, including those in Shoreland Zoning (Chapter IV).
Resources:
Old Orchard Beach, Maine
Old Orchard Beach, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10
Last Updated: 11.5.2024
Image source: Take Me 2 Old Orchard Beach Maine
What You Need to Know
Old Orchard, Maine has generous ADU rules and a few restrictions that you need to know. A maximum of 1,000 square feet not exceeding 50% of the primary dwelling's floor area is the size allowable. 2 additional parking spaces are required only for units over 600 square feet. Additionally, the ADU must comply with local utility requirements, including proof of adequate sewer, septic, and water services, ensuring that both the ADU and primary dwelling are properly supported.
Type of Permit Required
Applications for ADUs must go through administrative site plan review.
ADU Rules
Size & Floor Area:
Minimum floor area of 190 square feet.
Maximum floor area of 1,000 square feet or 50% of the primary dwelling's floor area, whichever is smaller.
ADU cannot have more than two bedrooms.
Floor area excludes unfinished attic, basement, or cellar spaces.
Floor area is measured from the interior faces of the walls.
Location & Setbacks:
Detached ADUs must meet the same setbacks as the principal residential structure and cannot exceed the height of the primary dwelling.
ADUs within the same structure or attached to the primary dwelling must meet the dimensional requirements for the district.
ADUs cannot be constructed in existing detached accessory structures.
ADUs outside of shoreland zones are not considered additional dwelling units for lot area or residential density calculations.
Parking Requirements:
No additional parking required for ADUs under 600 square feet, though additional parking should be provided as needed.
ADUs over 600 square feet must provide two additional off-street parking spaces.
Off-street parking spaces cannot be eliminated to convert an attached garage into an ADU.
Utilities:
If connected to public sewer, both the ADU and primary dwelling must be connected, with proof of adequate service.
If using a septic system, the system must meet Maine’s Minimum Lot Size law and state rules for subsurface wastewater disposal.
If connected to public water, proof of adequate service is required. If using a well, proof of potable water is needed.
Resources:
Cape Elizabeth, Maine
Cape Elizabeth, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10
Last Updated: 9/25/2025
Image source: Town of Cape Elizabeth, Maine
What You Need to Know
Cape Elizabeth has excellent rules for accessory dwelling units with few restrictions. The ADU must be located on a property with a single-family dwelling as the primary structure. Setbacks for the ADU depend on its location within or attached to the primary dwelling or in an existing accessory structure. Additionally, the ADU cannot be used as a short-term rental.
Type of Permit Required
ADUs in Cape Elizabeth are a permitted use and require a building permit.
ADU Rules
Single-family Parity: ADUs are allowed only on lots with a single-family dwelling as the principal structure.
Location: ADUs can be:
Within an existing dwelling unit,
Attached to or sharing a wall with the primary dwelling,
In a new structure or a converted accessory building (subject to accessory structure setbacks).
Density: ADUs are exempt from additional density or lot size requirements beyond those for the primary dwelling.
Setbacks:
ADUs attached to or built within the primary dwelling must follow the same setback and dimensional requirements for a single family home.
ADUs in existing accessory buildings must follow the original setbacks for those buildings.
Parking: No additional parking requirements beyond those for the primary dwelling.
Size:
Minimum size of 190 square feet.
Maximum size of 1,200 square feet and must be smaller than the primary dwelling.
Short-Term Rental Prohibition: ADUs cannot be used as short-term rentals (effective July 10, 2024).
Ownership: The primary dwelling and the ADU must stay under the same ownership.
Resources:
https://cms2.revize.com/revize/capeelizabethme/Documents/Government/Governing%20Documents/Ordinances/Zoning%20Ordinance.pdf Pages 176-177
Gorham, Maine
Gorham, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 8/10
Last Updated: 11.5.2024
Image source: Gorham Village Alliance Facebook
What You Need to Know
The property owner must live on the property (either in the main house or the accessory apartment) and the apartment must be no larger than 800 square feet with a maximum of two occupants. Additionally, the apartment must comply with local utility requirements, including being connected to public sewer or having an adequate septic system, and must meet zoning setbacks and access requirements.
Type of Permit Required
ADUs in Gorham are allowed in all zoning districts that allow single family homes.
ADU Rules
The property owner must reside in either the primary dwelling or the accessory apartment.
The apartment cannot exceed 800 square feet in size and must have at least 190 square feet of living space.
The number of occupants in the apartment is limited to two.
If public sewer is available, the accessory apartment must be connected to it. If not, the property must have a functioning septic system capable of handling the increased load.
For properties with private wells, proof of potable water is required.
The apartment must meet all zoning setbacks, including those in Shoreland areas, and provide proper access.
Only one accessory apartment is allowed per lot, and it will not be counted as an additional dwelling unit when calculating lot area per dwelling unit.
Resources:
https://www.gorham-me.org/sites/g/files/vyhlif4456/f/uploads/entire_searchable_ludc_07022024.pdf
Page 251 of PDF
Windham, Maine
Windham, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 6/10
Last Updated: 11.5.2024
Image source: Town of Windham Facebook
What You Need to Know
Detached ADU’s are not allowed. The ADU cannot exceed 800 square feet in size with a maximum of two bedrooms. Additionally, it must have its own entrance and comply with all building and septic system requirements. Parking for the accessory apartment cannot exceed the requirements for the primary dwelling.
Type of Permit Required
ADUs require approval from the Code Enforcement Officer
ADU Rules
Zoning Rules Summary for Accessory Apartments (Post-November 23, 2012):
The accessory apartment must be attached to the principal dwelling or located within an accessory building.
The property owner must live in either the principal dwelling or the accessory apartment.
The accessory apartment cannot exceed 800 square feet in total floor area and can have no more than two bedrooms.
It must have its own entrance and comply with building codes, requiring a certificate of occupancy from the Code Enforcement Officer.
Only one accessory apartment is allowed per lot, and it does not count toward the district’s maximum residential density.
The property must have an approved septic system, with the capacity documented in an HHE-200 form.
The parking requirement for the accessory apartment cannot exceed the parking required for the primary dwelling.
Resources:
Bath, Maine
Bath, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 8/10
Last Updated: 10.15.2024
Image source: Maine Street Maine Association
What You Need to Know
Permits are issued by Code Enforcement Office if attached to the primary dwelling, or the Planning Board if detached. ADU’s may be attached, with in or stand alone buildings and may not be rented for less than 90 days at a time.
Type of Permit Required
ADUs require a permit from the Code Enforcement Office or the Planning Board.
ADU Rules
One ADU is permitted per property that currently contains a primary dwelling unit.
The ADU can be built attached to or within the preexisting primary dwelling or as its own freestanding structure.
ADUs may only be built on properties in which the primary dwelling unit is either a single-family home or a duplex.
The ADU must be clearly accessory to the primary dwelling.
An ADU may be no larger than 850 square feet or 80% of the square footage of the primary residence, whichever value is lower.
An ADU may have at maximum two bedrooms
Each ADU requires at least one on-site parking space additional to the required parking for the primary residence. This requirement can be waived in the instance of an established off-site parking agreement.
ADUs must consider the privacy of the ADU and neighboring residences in their design.
ADUs may not exceed the height of the primary dwelling.
ADUs may not be used as a rental property for leases less than 90 days.
All ADUs must receive permits before construction from the CodeEnforcement Office if attached to the primary dwelling, or the Planning Board if detached.
All ADUs must meet the minimum requirements for a dwelling in relation to other ordinances not specific to ADUs, and must provide basic facilities for living, sleeping, cooking and sanitation.
Resources:
https://www.cityofbathmaine.gov/media/Departments/Planning/ADU%20Guidebook.9.27_KS.pdf
Brunswick, Maine
Brunswick, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 5/10
Last Updated: 9/23/2025
Image source: Town of Brunswick
What You Need to Know
No Development Review is required, but a safe water supply and appropriate waste management verification is needed prior to issuing a building permit.
Type of Permit Required
ADUs in Brunswick require a building permit.
ADU Rules
An accessory dwelling unit does not require Development Review.
The creation of an accessory dwelling unit shall not be counted for density purposes.
ADUs are allowed on lots used for single-family or two-family homes, either within the main house or in a detached structure.
Only one ADU is allowed per lot; any additional dwelling units must meet full density and dimensional requirements.
When possible, the ADU entrance should be located on a different side of the house than the main dwelling entrance.
An ADU may not exceed 1,100 square feet or 75 percent of the size of the primary dwelling, whichever is smaller. Floor area from a garage or carport that is part of the ADU does not count toward this limit.
A detached ADU may not be taller than the primary home, unless it is built above a garage and meets all dimensional requirements.
A detached ADU may not be taller than the primary home, unless it is built above a garage and meets all dimensional requirements.
The ADU must remain under the common ownership and cannot be sold separately as a condominium unit.
No permit for an accessory dwelling unit may be issued until the applicant has provided written verification from qualified professionals that the accessory dwelling
(a) will have adequate and safe water supply;
(b) will have adequate connection to wastewater services, as required by 30-A.M.R.S. §4364-B(7), as amended.
Resources:
https://www.brunswickme.gov/AgendaCenter/ViewFile/Item/2715?fileID=32584
Dayton, Maine
Dayton, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 7/10
Last Updated: 9.13.2024
Image source: Town of Dayton Facebook
What You Need to Know
The ADU Rules in Dayton are rather lengthy and complicated.
Type of Permit Required
ADUs are permitted through the Code Enforcement Officer of Dayton.
ADU Rules
The owner(s) of the lot on which the Principal Structure, a single-family dwelling, is located must reside in the principal structure or the Accessory Dwelling Unit. Neither the accessory dwelling unit nor the single-family dwelling shall be rented as a Short Term Rental for less than three consecutive months during a twelve (12) month period.
Ownership. The Principal Structure and the Accessory Dwelling Unit shall be held in the same ownership.
One of the occupants of the accessory unit shall be an immediate family member to the owner of the property and resident of the single-family dwelling unit. Immediate family as used in this Ordinance is defined as; spouse, parent, 100 grandparent, brother, sister, child, or grandchild related by blood, marriage, or adoption.
The number of occupants of the accessory unit is limited to two.
The living space, habitable area, of an accessory unit shall be a minimum of 190 square feet and shall not exceed the following percentage of living space of the single family dwelling to which the unit is accessory or the following maximum amounts, whichever are applicable:
The living space of the accessory dwelling unit may not exceed:
If the living space of the single family dwelling is:
40% or 750 sq ft, whichever is greater
Under 2,000 sq ft
35% or 750 sq ft, whichever is greater
2,000 sq ft to 3,000 sq ft
30% or 1,050 sq ft, whichever is greater
3,000 sq ft to 5,000 sq ft
20% or 1,500 sq ft, whichever is greater
Over 5,000 sq ft
Accessory dwelling units are exempt from density requirements or lot area requirements related to the area in which the accessory dwelling unit is constructed.
Parking. An accessory dwelling unit shall not be subject to any additional motor vehicle parking requirements beyond the parking requirements of the single family dwelling unit on the lot where the accessory dwelling unit is located.
Only one accessory dwelling unit per principal structure shall be permitted on a lot
An accessory dwelling unit may be constructed only:
Within an existing dwelling unit on the lot;
Attached to or sharing a wall with a single-family dwelling unit; or
As a new structure on the lot for the primary purpose of creating an accessory dwelling unit.
Accessory units are permitted on nonconforming lots, but the structures in which they are located (attached or detached), shall meet the lot coverage and setback requirements for the district in which they are located.
Any new structure constructed on the lot to be an accessory dwelling unit must meet the existing dimensional requirements as required by the municipality for an accessory structure.
Proper ingress and egress shall be provided to the accessory unit.
Attached and internal accessory units shall retain and respect the existing streetscape, character of the neighborhood, and preserve the single-family appearance, architectural style, and character of the original dwelling and property. Outside stairways (either open or closed) that service accessory units on upper stories are permitted, provided that they are integrated into and consistent with the architecture of the building. Outside stairways serving upper stories shall not be located on the side of the building that faces the street, except in the case of a building on a corner lot that fronts two or more streets, a stairway may be allowed on one of the sides of the building that faces a street if no reasonable alternative exists.
All municipal and state buildings codes in effect at the time of application must be followed.
An applicant for a permit for an accessory unit may also apply to the Zoning Board of Appeals for a limited reduction of yard size under Article 9 of this Ordinance where such reduction is reasonably necessary to allow construction of the accessory unit.
Should the owner(s) of the principal structure be found in non-compliance with the standards contained in this section, the non-compliance shall be considered a violation of this Ordinance, and the structure shall revert to a single family dwelling or the previous use.
For an accessory dwelling unit located within the same structure as a single family dwelling unit or attached to or sharing a wall with a single-family dwelling unit, dimensional requirements and setback requirements must be the same as the dimensional requirements and setback requirements of the single-family dwelling unit.
In order for an accessory unit to be located in a detached accessory structure, the following requirements must be met:
The detached accessory structure must be located no further than 100 feet from the nearest point of the principal structure;
The detached accessory structure must be designed and constructed in the style of a garage, barn, storage building, carriage house, or similar structure customarily located on the same lot with a single-family residence.
For an accessory dwelling unit permitted in an existing accessory structure, such as a barn or garage, as of July 1, 2023, the required setback requirements of the zoning district apply.
The accessory dwelling unit and the principal structure must be serviced by common utility meters, unless the utility company providing the service refuses to do so. Should a utility company be unwilling to service the accessory dwelling unit with a common meter, the applicant must provide the Code Enforcement Officer with a letter signed by the utility company so stating, with specific reasons for the refusal.
In order for an accessory dwelling unit to be added to an unsewered lot, the lot must comply with the requirements of the state minimum lot size law, 12 M.R.S.A. §§ 4807 – 4807-G for multiple unit housing as well as all the provisions of the Maine State Plumbing Code and the Town of Dayton Plumbing Ordinance. The applicant shall have the burden to establish the lot area, which may include a survey signed and sealed by a Professional Land Surveyor, at the discretion of the Code Enforcement Officer. The septic system on the property in question shall be functioning properly at the time of application for accessory dwelling unit approval.
The owner of an accessory dwelling unit must provide written verification that each unit of the accessory dwelling unit is connected to adequate water and wastewater services prior to certification of the accessory dwelling unit for occupancy or similar type of approval process. Written verification must include the following:
If an accessory dwelling unit is connected to a public, special district or other comparable sewer system, proof of adequate service to support any additional flow created by the unit and proof of payment for the connection to the sewer system.
If an accessory dwelling unit is connected to a septic system, proof of adequate sewage disposal for subsurface wastewater. The septic system must be verified as adequate by a local plumbing inspector pursuant under section 4221 of Title 30-A. Plans for subsurface wastewater disposal must be prepared by a licensed site evaluator in accordance with Subsurface Wastewater Disposal Rules.
If an accessory dwelling unit is connected to a public, special district or other centrally managed water system, proof of adequate service to support any additional flow created by the unit, proof of payment for the connection and the volume and supply of water required for the unit; and
If an accessory dwelling unit is connected to a well, proof of access to potable water. Any test of an existing well or proposed well must indicate that the water supply is potable and acceptable for domestic use.
Nothing contained in this Section 7.18 or elsewhere in this Ordinance shall be construed to:
exempt a subdivider from the requirements for division of a tract or parcel of land in accordance with the Town’s subdivision ordinance; or b) interfere with, abrogate or annul the validity or enforceability of any valid and enforceable easement, covenant, deed restriction or other agreement or instrument between private parties that imposes greater restrictions than those provided in this section, as long as the agreement does not abrogate rights under the United States Constitution or the Constitution of Maine.
Resources
Lyman, Maine
Lyman, ME Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 9/10
Last Updated: 9.5.2024
Image Source: Town of Lyman
What You Need To Know
Lyman, Maine allows ADU’s on all single family home lots.
Type of ADU Permit Required
No permit needed if the following conditions are met.
ADU Rules
Only one ADU is permitted per lot.
The lot meets all the current dimensional requirements.
The ADU shall not exceed six hundred (600) square feet.
The ADU shall be located either in the same building or an accessory building to the principal structure. If the accessory dwelling unit is located in the basement of a single family dwelling it must meet egress standards of the NFPA Life Safety Code #101 as well as all other required codes and standards.
Must maintain the exterior appearance of a single family home.
The unit must comply with all applicable building codes and expansion criteria of the Maine State Subsurface Wastewater Rules.
Driveways longer than two hundred (200) feet must provide an adequate emergency vehicle turnaround.
On street parking will not be permitted. Additional parking and turnaround space must be provided if needed.
Resources:
https://lyman-me.gov/wp-content/uploads/2021/02/TOL-Zoning_Ord_-amended_-071420.pdf - page 47 of PDF
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
Durham, Maine
Durham, Maine Accessory Dwelling Unit (ADU) Rules
City Acceptance Rating: 6/10
last updated: 2021
What You Need to Know:
Accessory apartments may be utilized for rental purposes as well as in-law accommodations subject to the following requirements:
The dwelling must have only one main entrance and all other entrances must appear subordinate to the main entrance. An entrance leading to a foyer with entrances leading from the foyer to the two dwelling units is permitted. No open or enclosed outside stairways shall be permitted above the first story.
The principal dwelling unit must have at least 1500 sq. ft. of floor area and the accessory apartment must not exceed 50% of the floor area of the principal dwelling unit. Floor area measurements must not include unfinished attic, basement or cellar spaces, nor public hallways or other common areas.
Only one accessory apartment may be permitted per lot. It must be made part of the main residence, or located in a separate building whose primary function is not as a dwelling unit, such as a garage or barn.
Accessory apartments may not be permitted for any nonconforming structure or use, where the nonconformity is due to the use of the premises, as opposed to nonconforming dimensional requirements
See full text here: Durham, Maine Performance Standards, Article 5, Page 19
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