Section 100-5-4 - ACCESSORY DWELLING UNITSA.GENERAL1. A municipality must allow, effective July 1, 2023, one accessory dwelling unit to be located on the same lot as a single-family dwelling unit in any area in which housing is allowed, subject to the requirements outlined below. The requirements listed in Section 4 apply to municipalities with and without zoning. Private, state or local standards such as homeowners' association regulation, deed restrictions, set back, density, septic requirements, shoreland zoning and subdivision law may also apply to lots.2. A municipal ordinance that allows more than one accessory dwelling unit or that allows accessory dwelling units to be established in relation to duplex, triplex and other multi-unit buildings shall be considered consistent with the goals of P.L. 2021 Ch. 672.B.REQUIREMENTS1. Accessory Dwelling Unit Allowance An accessory dwelling unit may be constructed only: a) Within an existing dwelling unit on the lot;b) Attached to a single-family dwelling unit; orc) As a new structure on the lot for the primary purpose of creating an accessory dwelling unit. A municipality may allow an accessory dwelling unit to be constructed or established within an existing accessory structure, except the setback requirements of Section 4(B)(3)(b)(i) shall apply.
2. Zoning With respect to accessory dwelling units, municipalities with zoning ordinances and municipalities without zoning must comply with the following conditions:
(a) At least one accessory dwelling unit must be allowed on any lot where a single-family dwelling unit is the principal structure; and(b) If more than one accessory dwelling unit has been constructed on a lot as a result of the allowance pursuant to this Section, the lot is not eligible for any additional units or increases in density, except as allowed by the municipality. Municipalities have the discretion to determine if a dwelling unit or accessory dwelling unit has been constructed on a lot for purposes of this provision.3. Other With respect to accessory dwelling units, municipalities must comply with the following conditions:
a) A municipality must exempt an accessory dwelling unit from any density requirements or lot area requirements related to the area in which the accessory dwelling unit is constructed;b) For an accessory dwelling unit located within the same structure as a single-family dwelling unit or attached to a single-family dwelling unit, the dimensional requirements and setback requirements must be the same as the dimensional requirements and setback requirements of the single-family dwelling unit; i. For an accessory dwelling unit permitted in an existing accessory building or secondary building or garage as of July 1, 2023, the required setback requirements in local ordinance of the existing accessory or secondary building apply.c) A municipality may establish more permissive dimensional requirements and setback requirements for an accessory dwelling unit.d) An accessory dwelling unit may 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.4. Size a) An accessory dwelling unit must be at least 190 square feet in size, unless the Technical Building Code and Standards Board, pursuant to 10 M.R.S. §9722, adopts a different minimum standard; if so, that standard applies.b) Municipalities may set a maximum size for accessory dwelling units in local ordinances, as long as accessory dwelling units are not less than 190 square feet.5. Water and Wastewater A municipality must require an owner of an accessory dwelling unit to provide written verification that the proposed accessory dwelling unit is to be 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:
a) 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;b) 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 to 30-A M.R.S. §4221. Plans for a subsurface wastewater disposal must be prepared by a licensed site evaluator in accordance with 10-144 C.M.R. Ch. 241, Subsurface Wastewater Disposal Rules;c) 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; andd) If an accessory dwelling unit is connected to a well, proof of access to potable water, including the standards outlined in 01-672 C.M.R. Ch. 10 section 10.25(J), Land Use Districts and Standards. Any test of an existing well or proposed well must indicate that the water supply is potable and acceptable for domestic use.C.MUNICIPAL IMPLEMENTATIONIn adopting an ordinance under this Section, a municipality may:
1. Establish an application and permitting process for accessory dwelling units;2. Impose fines for violations of building, zoning and utility requirements for accessory dwelling units; and3. Establish alternative criteria that are less restrictive than the above criteria in Section 4 for the approval of an accessory dwelling unit only in circumstances in which the municipality would be able to provide a variance pursuant to 30-A M.R.S. §4353(4)(A), (B), or (C).D.RATE OF GROWTH ORDINANCEA permit issued by a municipality for an accessory dwelling unit does not count as a permit issued toward a municipality's rate of growth ordinance pursuant to 30-A M.R.S. §4360.