What Are the Common Challenges and Delays Reported by Other ADU Applicants?
Building an Accessory Dwelling Unit can create valuable new possibilities for your property, but getting from an idea to a completed ADU involves more than choosing a design and beginning construction.
Massachusetts has made ADUs significantly more accessible. Since February 2, 2025, a qualifying single ADU is protected as a by-right use in single-family residential zoning districts, meaning municipalities generally cannot require a special permit or other discretionary zoning approval for the use. However, ADUs still need to meet applicable building, zoning, health, site, and permitting requirements.
That distinction is important.
By-right does not mean automatic approval or instant construction.
Understanding where complications can occur can help homeowners plan ahead, avoid preventable setbacks, and establish more realistic expectations for their project.
1. Zoning and Local Requirements
Massachusetts law provides important protections for qualifying ADUs, but municipalities can still apply certain reasonable local requirements.
Depending on the property and community, those can include dimensional setbacks, building height and bulk requirements, site plan review, and restrictions on short-term rentals.
A design that works well conceptually may therefore need to be adjusted after the property's specific requirements are reviewed.
How to prepare: Review zoning and site conditions before investing heavily in a final design. Early feasibility work can help identify whether the size and placement you're considering make sense for the property.
2. Incomplete Plans or Permit Applications
Even a qualifying by-right ADU still requires a building permit and compliance with applicable local rules and codes.
Missing information, incomplete drawings, conflicting details, or documents that do not adequately demonstrate code compliance can create additional rounds of review.
Every request for clarification or revision has the potential to add time to the process.
How to prepare: Build a complete project package before submission and make sure the professionals involved understand the requirements of the municipality where the project will be built.
3. Utilities and Infrastructure
One of the easiest aspects of an ADU to underestimate is how the new living space will be served.
Water, sewer, electrical service and other infrastructure may need to be evaluated as part of the project. Massachusetts guidance notes that, depending on the circumstances, an existing connection may need to be upgraded or a separate connection may reasonably be required to meet applicable standards.
Those discoveries can affect both the project's budget and schedule.
How to prepare: Evaluate utility capacity early rather than waiting until construction documents are nearly complete.
4. Septic and Title 5 Requirements
For homes that rely on septic systems, wastewater capacity can become a major feasibility consideration.
Massachusetts specifically allows applicable Title 5 requirements to apply to ADUs. State guidance also explains that a homeowner may need to upgrade an existing septic system to comply with Title 5 and applicable local regulations.
That doesn't mean a property with septic cannot support an ADU. It means septic capacity should be investigated early enough that it doesn't become an unexpected issue later.
How to prepare: If your property has a septic system, make wastewater capacity part of the initial feasibility conversation.
5. Design and Plan Revisions
Sometimes the first design simply isn't the design that gets built.
A proposed ADU may need adjustments because of setbacks, site constraints, building-code requirements, utilities, budget considerations, or feedback received during review.
Changes late in the process can affect multiple documents and sometimes require additional review.
How to prepare: Treat feasibility, budget and design as connected decisions. Designing around known property constraints from the beginning can reduce unnecessary redesign.
6. Site Conditions
What works on paper still has to work on the property.
Slope, drainage, existing structures, trees, access, foundation conditions and other physical characteristics can influence where and how an ADU is constructed.
For homeowners, this is one reason an ADU shouldn't be evaluated solely by looking at available backyard space.
How to prepare: A thorough site evaluation before design and construction can uncover potential complications while there is still time to plan around them.
7. Local Review and Coordination
The statewide ADU law establishes important zoning protections, but municipalities remain involved in administering building permits and other applicable requirements. Massachusetts also advises homeowners with property-specific questions to work with their city or town and trusted building, legal, or real-estate professionals.
Depending on the project, several disciplines or agencies may need to be coordinated.
The more moving pieces involved, the more important organization becomes.
How to prepare: Know which approvals apply to your project and build those reviews into the schedule rather than assuming every step will happen simultaneously.
8. Construction Scheduling and Availability
Receiving approvals isn't the end of the planning process.
ADUs require many of the same skilled trades and project-management resources as other residential construction projects. Contractor schedules, material lead times, inspections, subcontractor coordination and weather can all influence the construction timeline.
Starting those conversations early can help homeowners develop a more realistic path from approval to completion.
Can ADU Delays Be Avoided?
Not every delay can be prevented.
Unexpected site conditions, agency review times, design changes and construction variables are part of residential building.
But many problems are easier to manage when they're identified before construction begins.
That's why the earliest stages of an ADU project matter so much.
Before committing to a design, homeowners should understand:
- What their property can realistically support
- Which local requirements apply
- Whether utilities and septic are adequate
- What approvals will be necessary
- What the project may realistically cost
- How design decisions affect feasibility
- What a reasonable project timeline looks like
The objective isn't simply to move quickly.
It's to move forward with fewer surprises.
Where Landmark Associates Can Help
An ADU project involves decisions long before the first day of construction.
Landmark Associates helps homeowners evaluate those decisions as part of the overall process, including:
Property Feasibility
Understanding the opportunities and potential constraints of your property.
Zoning and Code Guidance
Helping identify the requirements that could influence your project.
Design Coordination
Developing a design around your property, goals and practical constraints.
Budget Planning
Establishing realistic expectations before major decisions are made.
Permitting Assistance
Helping organize and navigate the documentation and approval process.
Full-Service Construction
Managing the project from planning through construction and completion.
Instead of discovering potential obstacles one at a time, the goal is to identify as many as possible before they become expensive or time-consuming problems.
Planning an ADU? Start Before the Problems Start.
Massachusetts' updated ADU laws have created new opportunities for homeowners across the Commonwealth. A qualifying protected-use ADU generally cannot be subjected to a special permit, owner-occupancy requirement, or unreasonable zoning restrictions, but homeowners still need to navigate applicable building, dimensional, health, infrastructure and local requirements.
That's why a successful ADU project doesn't begin with construction.
It begins with understanding your property.
If you're considering an ADU, Landmark Associates can help you evaluate what's possible, identify potential challenges, and develop a clear path forward.
Ready to Explore Your Property?
Don't wait for a challenge to become a delay.
Contact Landmark Associates to discuss your ADU project and take the next step with confidence.
📞 (508) 482-0104
🌐 www.landmarkassoc.com
Add Space. Add Value. Build with Confidence.
This article is intended for general informational purposes and is not legal or zoning advice. ADU requirements and site conditions vary by property and municipality.



