ADU Permit Process in Boston, MA
Step-by-step guide to the ADU permit process in Boston, Massachusetts. Learn whether you need a special permit or can build by right.
Boston's Local ADU Ordinance
Unlike most Massachusetts municipalities, Boston operates under its own zoning charter with ADU-specific rules that may differ from the state baseline. This means some state-level rights may not apply in the same way. Check the specific rules below for Boston's requirements.
Step-by-Step Permit Process
1. Hire an architect or designer to create ADU plans that comply with Boston's zoning and building codes. 2. Submit plans to Boston's building department for review. 3. Receive your building permit (typically 4-8 weeks). 4. Begin construction with licensed contractors. 5. Schedule required inspections during construction. 6. Receive certificate of occupancy upon completion.
Required Documents
You'll need the following documents when applying for an ADU permit in Boston: architectural plans with dimensions and elevations, a site plan showing the ADU location relative to property lines, proof of property ownership, a completed building permit application, and documentation of building code compliance (energy, structural, fire safety).
Inspections and Occupancy
During ADU construction in Boston, you'll need inspections at key milestones: foundation, framing, rough plumbing/electrical/mechanical, insulation, and final inspection. After passing the final inspection, you'll receive a certificate of occupancy that allows legal use of the ADU as a dwelling unit.
Boston Building Department
The Boston Inspectional Services Department is your first point of contact for ADU permits. They are located at 1010 Massachusetts Ave # 5, Boston, MA 02118, USA. Call (617) 635-5300 for questions about your ADU project. Visit their website for forms and filing instructions.
Important: State Baseline Data
The information on this page reflects Massachusetts state baseline rules. Boston may have additional local requirements. We recommend confirming with your local building department before starting your project.
Boston ADU Rules at a Glance
Max Size
1250 sq ft
% of Home
75%
Max Height
25 ft
Max Stories
2
Front Setback
25 ft
Side Setback
5 ft
Rear Setback
5 ft
Parking
1 space(s)
Approval
BY RIGHT
Owner Occupancy
Required
Rental Allowed
Yes
Short-Term Rental
Not allowed
Boston Building Department
Boston Inspectional Services Department
1010 Massachusetts Ave # 5, Boston, MA 02118, USA
Phone: (617) 635-5300
Frequently Asked Questions
Do I need a special permit for an ADU in Boston?
No. ADUs in Boston are approved by right — you submit your plans to the building department and receive a building permit without a public hearing or special permit process. This is significantly faster than the old process.
How long does the ADU permit process take in Boston?
With by-right approval in Boston, the permit process typically takes 4-8 weeks from plan submission to building permit issuance. There is no public hearing or zoning board review, which eliminates the longest delays in the process.
What documents do I need for an ADU permit in Boston?
You'll typically need: architectural plans showing the ADU layout and dimensions, a site plan showing setbacks and lot coverage, proof of ownership, and a building permit application. Boston may also require energy code compliance documentation and septic/sewer capacity verification.
How do I contact Boston's building department about an ADU?
Contact the Boston Inspectional Services Department, located at 1010 Massachusetts Ave # 5, Boston, MA 02118, USA, by calling (617) 635-5300. They can answer questions about ADU permit requirements, plan review, inspections, and local zoning rules specific to Boston. You can also visit their website for forms and filing instructions.
Can I build an ADU without a permit in Boston?
No. All ADUs in Boston require a building permit regardless of size or type. Building without a permit can result in fines, required demolition, and complications when selling your property. The permit ensures your ADU meets building codes for safety, structural integrity, and habitability.
How accurate is the ADU data for Boston?
The information on this page reflects Massachusetts state baseline rules under the Affordable Homes Act. Boston may have additional local requirements that differ from the state baseline. We recommend confirming with your local building department before starting your project.
Where can I find all ADU regulations for Boston?
Visit our complete ADU rules page for Boston, MA for a full overview of zoning, permits, size limits, setbacks, parking, and costs. We cover all Massachusetts municipalities with data sourced from local ordinances and state law.
Check Your Address
See exactly what ADU rules apply to your specific property in Boston.