ADU Bylaw 5/19/2025

§ 500-25.1 Accessory Dwelling Unit

A. Purpose and Intent

1.) An Accessory Dwelling Unit (ADU) is an alternative type of housing that provides Plainville with additional housing supply options without requiring additional land development. The design and implementation of an ADU is expected to fit on a lot in a single-family residential zoning district.

2.) ADUs are permitted As of Right per Massachusetts General Laws (MGL), Chapter (c) 40A, §§ 1A and 3.. The Town has established §500-25.1 of these Zoning Bylaws in addition to 760 CMR 71.00 in order to provide further guidance and to reasonably regulate the construction of ADUs within single-family zoning districts, while preserving the residential character of a neighborhood.

3.) Nothing within this Bylaw shall be construed to conflict with MGL c 40A, or 760 CMR 71.00.

B. Definitions

The following terms shall have the following meanings for the purposes of this bylaw.

1.) ACCESSORY DWELLING UNIT (ADU). A self-contained housing unit, inclusive of sleeping, cooking and sanitary facilities on the same Lot as a Principal Dwelling, subject to otherwise applicable dimensional and parking requirements, that: (a) maintains a separate entrance, either directly from the outside or through an entry hall or corridor shared with the Principal Dwelling sufficient to meet the requirements of the Building Code for safe egress; (b) is not larger in Gross Floor Area than ½ the Gross Floor Area of the Principal Dwelling or 900 square feet, whichever is smaller; and (c) is subject to such additional restrictions as may be imposed by a municipality including, but not limited to, additional size restrictions, and restrictions or prohibitions on Short-term Rental as defined in section 1 of chapter 64G; provided, however, that no Municipality shall unreasonably restrict the creation or rental of an ADU that is not a Short-term Rental.

2.) BUILDING, ATTACHED: A building having any portion of one or more walls in common.

3.) BUILDING, DETACHED: A building completely surrounded by open space on all sides.

4.) DWELLING UNIT: A single housing unit providing complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation. This definition does not include a trailer, however mounted.

5.) LOT: An area of land within definite boundaries that is used, or available for use, as the site of a structure or structures, regardless of whether the site conforms to requirements of Zoning.

6.) PROTECTED USE ADU: An attached or detached ADU that is located, or is proposed to be located, on a Lot in a Single-family Residential Zoning District and is protected by M.G.L. c. 40A, § 3, provided that only one ADU on a lot may qualify as a Protected Use ADU. An ADU that is nonconforming to Zoning shall still qualify as a Protected Use ADU if it otherwise meets this definition.

7.) PRINCIPAL DWELLING: A structure that contains at least one Dwelling Unit and is located on the same lot as an ADU.

8.) SINGLE-FAMILY DWELLING: A structure on a Lot containing not more than one Dwelling Unit.

9.) SINGLE-FAMILY RESIDENTIAL ZONING DISTRICT: Any Zoning District where Single-Family Residential Dwellings are a permitted or an allowable use, including any Zoning District where Single-Family Residential Dwellings are allowed as of right, by special permit, variance, waiver, or other zoning relief or discretionary zoning approval.

10.) TRANSIT STATION: A Subway Station, Commuter Rail Station, Ferry Terminal or Bus Station.

C. Procedural Requirements:

1.) A Building Permit application for an ADU shall be filed with the Building Commissioner.

2.) The ADU shall comply with the dimensional standards in §500-17 and the use regulation schedule in § 500-19.

3.) The ADU and the principal dwelling shall remain on the same Lot and shall not be divided onto two (2) separate lots.

4.) The Zoning Board of Appeals shall make a finding, when applicable, on the placement or addition of an ADU on a pre-existing non-conforming lot in accordance with MGL Chapter (c) 40A, § 6.

D. Use and Dimensional Requirements

1.) The Building Commissioner shall issue a Building Permit authorizing the installation and use of an Protected Use ADU to a principal single-family dwelling in a single-family zoning district provided the following conditions are met.

a. The Protected Use ADU shall only be located in a single-family residential zoning district on a lot with an existing principal dwelling. The principal dwelling shall be the primary use while the Protected Use ADU shall be an considered an accessory.

b. The Protected Use ADU may be located in the principal dwelling.

c. The principal dwelling may be altered to include a Protected Use ADU.

d. The Protected Use ADU shall consist of a complete, separate housekeeping unit containing both kitchen and bath.

e. The habitable area of the Protected Use ADU shall not exceed ½ the gross floor area of the principal dwelling or 900 square feet, whichever is smaller.

f. All Protected Use ADUs must comply with all applicable requirements of law including of those of the building, fire, sanitary, department of public works, and stormwater state codes and/or local Bylaw, regulations, and policies.

g. The Protected Use ADU is located on the lot so it does not impede vehicular access and circulation of the Lot, roadways, and sidewalks.

h. Sufficient and appropriate space for one (1) additional parking space shall be provided by the owner to serve the Protected Use ADU on a lot located outside a .5-mile radius of a Transit Station; lots within a 0.5-mile radius of a Transit Station shall have no requirement to provide for such an additional parking space. Said parking space shall have vehicular access to the driveway. Stacking of vehicles for the different dwelling units shall not be allowed. A separate driveway opening for the ADU shall not be allowed.

i. The use of any ADU for short-term rentals, as defined in MGL Chapter 64G Section 1, shall be prohibited.

2.) The Protected Use ADU shall comply with the dimensional requirements pursuant to § 500-25.1(C)(2). In order to encourage the development of housing units for disabled and handicapped individuals and persons with limited mobility, the Building Commissioner may allow for reasonable deviation from the stated conditions where necessary to install features that facilitate access and mobility for disabled persons.

3.) Prior to the issuance of a Building Permit, a floor plan must be submitted showing the proposed interior and exterior changes to the building.

E. ADU Special Permit

1.) Pursuant to MGL Chapter 40A Section 3A, more than one ADU within a single-family home or house lot shall require a Special Permit pursuant to MGL Chapter 40A Section 9 and § 500-20 of the Town of Plainville Zoning Bylaws.

2.) Special Permit Granting Authority. The Planning Board shall act as the special permit granting authority for applications submitted under this section of the Zoning Bylaw and may adopt and from time to time amend reasonable regulations for the administration of this bylaw.

F. Administration and Enforcement

1.) It shall be the duty of the Building Commissioner as Zoning Enforcement Officer to administer and enforce the provisions of this Bylaw.

2.) No building shall be changed in use or configuration until the Building Commissioner has issued a permit. No building permit shall be issued until water, sewer, septic, and/or Title V connection permit, when applicable, has been first obtained from the Department of Public Works and/or Board of Health. Any building alteration shall conform to all adopted state and town laws, bylaws, codes and regulations. No building shall be occupied until a certificate of occupancy has been issued by the Building Commissioner where required.

3.) The Building Commissioner shall refuse to issue any permit, which would result in a violation of any provision of this chapter or in a violation of the conditions or terms of any special permit or variance granted by the Zoning Board of Appeals or its agent.

4.) The Building Commissioner shall have the authority to issue a cease and desist order on any work in progress or on the use of any premises, either of which are in violation of the provisions of this chapter.

5.) Construction or use according to the building permit shall conform to any subsequent amendments to these provisions, MGL Chapter 40A, and/or Massachusetts Building Code.

And amending § 500-21(C) after the words:

“Single-family residences -2 spaces for each individual dwelling unit” by adding the following:

“Accessory Dwelling Unit-      1 space for each individual dwelling unit outside of a 0.5 mile radius of a Transit Station as defined in §500-25.1(B)(10) and zero (0) spaces for each unit within a 0.5. radius of a Transit Station as so defined”