Who Should Approve ADUs? Balancing Community Control And Efficient Housing
The Commonwealth of Massachusetts has enacted legislation permitting the creation of Accessory Dwelling Units (ADUs) throughout the state in any zoning district where single-family homes are allowed. Under this law, homeowners may add smaller, self-contained housing units—limited to 900 square feet or half the size of the primary dwelling, whichever is smaller—on the same lot as their primary residence. This initiative aims to increase affordable housing options across communities.
However, not every property will automatically qualify to build an ADU. The legislation requires ADUs to comply with specific criteria, including size limits, dimensional standards, parking requirements, and compliance with building and safety codes, ensuring they align with local regulations.
Crucially, each municipality—Millbury included—has the authority to adopt its own zoning bylaws to locally implement and enforce the state’s ADU provisions. While these bylaws must be consistent with the state law, they allow communities to tailor requirements and processes based on local housing goals, design preferences, and planning priorities. This flexibility helps towns balance the need for increased housing with preserving neighborhood compatibility and exercising appropriate planning oversight.
Accessory Dwelling Units (ADUs) have emerged as an important solution to meet housing needs across Massachusetts communities. The proposed zoning bylaw for Millbury introduces the option for ADU approvals to be handled by the Building Inspector, a change from the current practice where the five-member Planning Board holds this authority. While both approval routes are legally valid, choosing between them carries significant practical and procedural consequences. This post explores the advantages and disadvantages of each approach and what it means for a town governed by a five-member Planning Board.
What “By Right” Approval Really Means
A key point often misunderstood by board members and the public is the meaning of “by right” approval under Massachusetts land use law. Many assume it means automatic or guaranteed approval without review. Legally, “by right” means an applicant must be approved if the ADU meets the objective standards set forth in the zoning bylaw and state law.
This means the approving official, typically the Building Inspector, must approve the application if it complies with all clear dimensional, parking, and safety criteria. However, this is not an automatic approval upon submission:
The Building Inspector reviews whether the ADU meets all objective regulatory requirements.
The Inspector may deny or require changes if the application does not comply.
The approval is a ministerial act—mandatory if all criteria are met, but conditioned on compliance.
If denied, the applicant can appeal or revise the plans to meet standards.
Does “By Right” Mean the Community Has No Control?
No. “By right” approval does not mean the community or local government loses all authority to regulate ADUs or set reasonable conditions.
While “by right” means an applicant must be approved if the ADU meets the clear, objective standards set by zoning and state law, those standards themselves reflect community-established rules and conditions. For example, the Millbury bylaw sets dimensional limits, parking requirements, and building code compliance that the ADU must meet to qualify for “by right” approval.
The community has shaped these standards through the zoning bylaw and can update them within legal limits. The Building Inspector applies these rules ministerially but must enforce all reasonable conditions already established in law.
However, unlike discretionary Planning Board review where additional site-specific conditions can be imposed case-by-case, the “by right” pathway relies on a fixed set of objective standards to balance homeowner rights and community interests.
Therefore, “by right” means certainty and predictability in approvals when complying with community rules — not a loss of local control or oversight.
Pros and Cons of Approval by Building Inspector
Pros:
Streamlined Process: Building Inspectors typically handle building permits routinely and can approve Protected Use ADUs by right, as long as dimensional and safety code requirements are met. This can speed up the timeline for property owners.
Clear Standards: The Building Inspector’s approval is mostly ministerial, focusing on objective criteria like size, parking, and compliance with building and fire codes.
Less Ambiguity: Since approvals are by-right and based on code compliance, there's less room for subjective judgment or discretionary denial.
Cons:
Limited Discretion: The Building Inspector cannot consider neighborhood context or planning objectives beyond the set dimensional and safety criteria.
Potential Overlook of Broader Planning Goals: Without a deliberative board, there’s less opportunity to address cumulative impacts, design compatibility, or aesthetics.
Fewer Public Input Opportunities: Building permits generally have limited or no public hearing processes, translating to less opportunity for community engagement.
Pros and Cons of Approval by Planning Board (Five Members)
Pros:
Community and Planning Input: The Planning Board can evaluate ADU proposals with a holistic view, considering neighborhood character, planning goals, and the cumulative effect of ADUs in the district.
Public Hearing Process: The Planning Board’s decision often requires hearings where abutters and the public can provide input before a permit is granted or denied.
Flexibility to Impose Conditions: The Board may attach reasonable conditions to mitigate impacts, such as landscaping buffers, design elements, or parking modifications.
Checks and Balances: A five-member board provides collective deliberation, reducing the risk of arbitrary decisions by a single official.
Cons:
Longer Approval Time: The hearing and deliberation process naturally takes longer than ministerial approval by the Building Inspector.
Potential for Subjectivity: Board members may have varying opinions, and decisions might be influenced by local politics or opposition.
Complexity and Uncertainty for Applicants: Applicants face more procedural steps and could encounter uncertainty if the board is divided or if conditions are onerous.
Quorum Challenges: With a small five-member board, absences can affect quorum and delay decisions.
How the Five-Member Planning Board Regulates ADUs
A Planning Board with five members typically operates by majority vote. For an ADU special permit or approval process, this board:
Conducts public hearings where applicants present their plans and neighbors can comment.
Evaluates applications against local zoning bylaws (such as dimensional standards and parking requirements) and planning objectives reflected in the town’s zoning code.
Has authority to impose reasonable conditions intended to minimize negative impacts while facilitating ADU creation.
Issues approvals subject to a simple majority vote (often three out of five members).
Deliberates collectively, providing transparency and greater community accountability.
Follows state law and local procedural rules, including timely decision deadlines.
This regulation method provides a balance between supporting housing production and ensuring community input and planning standards are met. However, it requires applicants and residents to engage thoughtfully in the process, accepting longer timelines for broader community review.
Conclusion
The choice between the Planning Board or Building Inspector as the approval authority for ADUs reflects a trade-off between efficiency and deliberative public engagement. Building Inspectors provide faster, objective, code-based approvals but with limited oversight beyond technical compliance. Meanwhile, a five-member Planning Board offers collective decision-making, public participation, and planning discretion, promoting thoughtful integration of ADUs into neighborhoods but at the cost of complexity and time.
Communities like Millbury should weigh these pros and cons carefully when setting local policies for ADU approvals. The goal is to balance expanding housing opportunities with preserving community character and ensuring transparent, fair processes.
The ADU photograph attached to this blog post is by Abodu, a California-based company specializing in ADUs for that region. This is the Abodu Two model, featuring two bedrooms and one bathroom, all within a compact 610± square foot space.