Accessory Dwelling Units

"This is the draft bylaw as approved at Town Meeting on December 12, 2024. This bylaw will be added to the Middleton Zoning Code upon final approval by the Office of the Attorney General."

7.5 ACCESSORY DWELLING UNITS

7.5.1 Definition.

An Accessory Dwelling Unit (“ADU”) is an attached or detached Dwelling Unit that is accessory to a principal single-family Dwelling Unit and is otherwise defined in accordance with the provisions of G.L. c. 40A, §1A, as may be amended.

7.5.2 Use Schedule.

1. ADUs are allowed as a matter of right in the R-1a, R-1b, RA, and R-2 Zoning Districts, subject to the requirements of this Section. ADUs are prohibited in all other districts.

2. Only one ADU is allowed as a matter of right on any property.

3. ADUs may not be used as Short-Term Rentals, as such term is defined in G.L. c. 64G, §1 or otherwise rented for a period shorter than thirty-one (31) days.

7.5.3 Dimensional Requirements.

1. An ADU may be no larger in gross floor area than one half of the gross floor area of the principal Dwelling Unit on the property or 900 square feet, whichever is less.

2. ADUs shall comply with any and all lot area, frontage, setback, height, lot width and lot coverage requirements, as may be applicable to single family homes, as contained in Attachment 1 – Table of Dimensional Requirements of this Zoning Bylaw. a. Single Family Dwellings and ADU’s in the R2 District are to comply with the dimensional controls for the R1b District. b. Conversions of existing non-residential accessory structures to ADUs are permitted provided that the existing accessory structure complies with the above-described dimensional requirements.

3. ADUs are limited to a maximum of two stories.

4. ADUs shall be designed and constructed so that no portion thereof shall be closer to the front lot line than the primary dwelling.

7.5.4 Parking.

1. At least one (1) off-street parking space must be provided for all ADUs. Parking may be in a driveway or a garage but the parking space may not be a tandem space with a parking space for the primary single-family structure.

2. The construction of a new garage to serve an ADU shall require a Special Permit from the Board of Appeals.

7.5.5 Site Plan Approval.

 All ADUs are required to obtain Site Plan Approval from the Board of Appeals pursuant to the procedures in Section 9.5 of this Zoning Bylaw, provided that the Site Plan Review criteria shall be limited to the following:

1. The ADU should minimize tree, vegetation and soil removal and grade changes.

2. Architectural style should be compatible with the existing principal dwelling on the subject property.

3. The ADU shall be serviced with adequate water supply and sewer or septic service.

4. The Plan shall demonstrate adequate parking, as required hereunder and shall maximize convenience and safety for vehicular and pedestrian movement within the property and in relation to adjacent ways. The Board of Appeals may request reasonable plan modifications of the Site Plan for an ADU and may impose reasonable conditions that are not inconsistent with this bylaw or the provisions of G.L. c. 40A, §3.

7.5.6 Relationship to non-conformities.

If an ADU is proposed for a pre-existing, nonconforming single-family primary residence, the requirements of Sections 3.3.4 and 3.3.5 of this Zoning Bylaw shall apply provided that no special permit may consider the ADU use or impose conditions on such use.