Middleton

• Middleton adopted its ADU bylaw (Section 7.5) at Town Meeting on December 12, 2024, proactively before the state deadline.
• ADUs are allowed by right in all residential districts (R-1a, R-1b, RA, R-2) but require Site Plan Approval from the Board of Appeals (a streamlined, non-discretionary review).
• Short-term rentals are prohibited -- ADUs may not be rented for less than 31 consecutive days.
• Maximum size is 900 sq ft or 50% of principal dwelling, whichever is smaller.
• Tandem parking is explicitly prohibited -- the required ADU parking space cannot share space with the primary dwelling's parking.

1. Contact the Building Department: Reach out to the Middleton Planning Department / Building Commissioner at 48 South Main Street to discuss your project.
2. Prepare site plan: Develop a site plan that addresses the four review criteria: (a) minimize tree/vegetation/soil removal and grade changes, (b) architectural compatibility with principal dwelling, (c) adequate water/sewer/septic service, and (d) adequate parking with safe vehicular and pedestrian movement.
3. Site Plan Approval: Submit for Site Plan Approval from the Board of Appeals pursuant to Section 9.5 of the Zoning Bylaw. This is a streamlined review, not a discretionary special permit. The Board may request reasonable plan modifications and impose reasonable conditions consistent with the bylaw and G.L. c. 40A, Section 3.
4. Building permit: Obtain a building permit after Site Plan Approval.
5. Construction and inspection: Build in accordance with approved plans and the Massachusetts State Building Code (780 CMR).

Note: If your ADU requires a new garage, that garage construction requires a separate Special Permit from the Board of Appeals.

• Maximum size: 900 square feet or 50% of the gross floor area of the principal dwelling, whichever is less.
• Types: Attached, detached, or internal. Conversions of existing non-residential accessory structures are permitted provided they comply with dimensional requirements.
• Dimensional requirements: ADUs must comply with all lot area, frontage, setback, height, lot width, and lot coverage requirements applicable to single-family homes per Attachment 1 - Table of Dimensional Requirements.
• R-2 District: Single family dwellings and ADUs in R-2 must comply with R-1b dimensional controls.
• Front setback: No portion of the ADU may be closer to the front lot line than the primary dwelling.
• Architectural compatibility: Architectural style should be compatible with the existing principal dwelling on the subject property.
• Environmental: The ADU should minimize tree, vegetation, and soil removal and grade changes.

• One off-street parking space required for all ADUs.
• Tandem parking explicitly prohibited: The ADU parking space may not be a tandem space with a parking space for the primary single-family structure. Parking may be in a driveway or a garage.
• New garage: Construction of a new garage to serve an ADU requires a Special Permit from the Board of Appeals.
• Site plan must demonstrate: Adequate parking with maximum convenience and safety for vehicular and pedestrian movement within the property and in relation to adjacent ways.

• Site Plan Approval: While ADUs are by-right, all ADUs must obtain Site Plan Approval from the Board of Appeals. This is a streamlined review with criteria limited to four specific areas (environmental impact, architectural compatibility, water/sewer/septic adequacy, and parking/circulation). It is not a discretionary special permit.
• Short-term rental prohibition: ADUs may not be used as Short-Term Rentals as defined in G.L. c. 64G, Section 1, or otherwise rented for less than 31 consecutive days.
• Non-conforming lots: If an ADU is proposed for a pre-existing, non-conforming single-family primary residence, the requirements of Sections 3.3.4 and 3.3.5 of the Zoning Bylaw apply, but no special permit may consider the ADU use or impose conditions on such use.
• Water/sewer/septic: The ADU must be serviced with adequate water supply and sewer or septic service.
• Proactive adoption: Middleton adopted this clean, concise 2-page bylaw proactively before the state deadline, demonstrating readiness for ADU development.

The following is the full text of Middleton's ADU Zoning Bylaw Section 7.5, as approved at Town Meeting on December 12, 2024.

ARTICLE 1. Accessory Dwelling Unit ("ADU") Zoning Bylaw

On petition of the Middleton Planning Board to see if the Town will vote to amend its zoning bylaws with respect to Accessory Dwelling Units, by adding the following language:

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, Section 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, Section 1 or otherwise rented for a period shorter than thirty-one (31) consecutive 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 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, Section 3.

7.5.6 Relationship to non-conformities.

If an ADU is proposed for a pre-existing, non-conforming 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.

And to amend Attachment 2 - Table of Use Regulations of the Zoning Bylaws by adding a new row for Accessory Dwelling Unit under Accessory Uses, noting that the use is allowed (Y) in the R-1a, R1b, RA, & R-2 Districts but also adding a footnote that states "See Section 7.5 for additional requirements for Accessory Dwelling Units."

Middleton has not adopted the Stretch Energy Code. Your ADU project follows the Base Energy Code (IECC 2021 with MA amendments) using the prescriptive compliance path.

This means no HERS rater is required, which can save $500–$1,500 in testing costs. You still must meet minimum insulation, window, and mechanical efficiency standards per code, but you don't need a third-party energy rating.

Builders can optionally choose the ERI/HERS performance path for more design flexibility (e.g., trading off insulation thickness for higher-efficiency equipment).

The following local provisions are preempted by the Massachusetts Affordable Homes Act (Section 8, Chapter 150, Acts of 2024) and 760 CMR 71.00:

• Owner-occupancy requirements: Cannot be imposed on either the principal dwelling or the ADU. Middleton's bylaw does not include an owner-occupancy requirement, consistent with state law.

Note: Middleton's bylaw is generally well-aligned with state law. The Site Plan Approval process is structured as a limited, non-discretionary review rather than a special permit, which appears consistent with the state law's by-right requirement. However, the requirement that the Board of Appeals may impose "reasonable conditions" could be tested if conditions are perceived as unreasonably restrictive.

The short-term rental prohibition (31 consecutive day minimum) appears permissible under state law, which explicitly allows municipalities to restrict or prohibit short-term rental use of ADUs.

• Middleton ADU Zoning Bylaw - Town Meeting December 2024
• Town of Middleton ADU Page
• Town of Middleton Website