Permitting Your Accessory Dwelling Unit
Research what type of permits you will need to build your ADU and learn more about the permitting process.
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Still have questions? Contact:
Housing
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12 Channel Street
9th FloorBoston, MA 02210
Permitting Overview
Once you've finalized your ADU design, it's time to apply for a building permit!
The permitting stage of the ADU process is one of the first major project milestones. During this process, you will submit your completed ADU plans and other related documentation to the City's Inspectional Services Department in order to receive a permit to build your ADU.
Before You Start: ensure your design is finalized and financing is secured
In order to receive a building permit, your ADU designs must be finalized and your project team - which may include an architect, contractor, and/or other building professionals - should be in place. It is also recommended that you have most or all financing for your project secured, and that you have budgeted for any fees associated with permitting your ADU. For more information about how to plan, design, and pay for your ADU, please see our page Planning Your ADU.
Which Permits Will I Need?
You will need to obtain a long-form building permit in order to construct your ADU.
The City's Inspectional Services Department (ISD) requires that a long-form permit be filed for all new construction projects or projects that include major alterations to an existing home. All ADUs require a long-form permit. It is recommended that your licensed contractor apply for all permits on your behalf.
Other required documents
Depending on the scope of your project, you may need to submit some of the following documents alongside a long-form permit.
- Homeowner Exemption Form (only applies for homeowners of single-family homes who intend to perform the construction work without a general contractor)
- Application to Install a Fire Protection System (Sprinkler)
- Electrical and mechanical permits
- Foundation permit
Permitting Process
APPLYING FOR YOUR PERMIT
To apply for your long-form permit, you can either apply online or in person at ISD's offices at 1010 Massachusetts Avenue. You will need to have various documents prepared to submit, including a copy of your contractor agreement, proof that your contractor has Worker's Compensation, and various site, plot, and floor plans of your proposed ADU.
Keep in mind that there are fees associated with applying for a building permit. The fees you need to pay are determined by the type of permits you're applying for and the scope of your project.
TIPS TO KEEP IN MIND
- Ensure that you've submitted all required documents as a complete application package.
- The process to review your application depends on the size and scope of your project. It may take up to 5 weeks for review to be completed, or longer if your project requires zoning relief or if documents were submitted incorrectly.
- Use ISD's permit finder tool to check the status of your building permit.
- You must receive a printed building permit card before you can start work on your project. If you applied online, you can print your building permit at home.
- Your building permit is valid for six months after the date of issue, and you are required to work without interruption during this time. In some cases, you may be able to extend your permit for another 180 days.
Do you have more questions on the permitting your ADU? The following guide includes step-by-step instructions on how to navigate the process.
Zoning Board of Appeal
In some cases, your project may require approval from the Zoning Board of Appeal in order to receive a building permit.
During the process of reviewing your building permit application, an ISD Plans Examiner will review your building plans and ensure they meet Boston's Zoning Code requirements. If your building plans do not comply with the zoning rules relevant to your property, you will need to be granted zoning relief from Boston's Zoning Board of Appeal (ZBA).
projects that may require zoning relief
- Attached or Detached ADUs (Mattapan homeowners may build attached and detached ADUs without zoning relief)
- Attached or Detached ADUs in Mattapan, if out of compliance with requirements outlined in Article 2 and/or dimensional requirements outlined in Article 60, Table D
- Internal ADUs that propose additional gross square footage and/or exterior alterations
To learn more about zoning review and the ZBA, click the video link below.
Zoning board of appeal process
If, during review of your long-form building permit application, your ISD Plans Examiner determines that your project contains one or more zoning violations, you will receive a Zoning Code Refusal Letter. This letter identifies which provisions in the Zoning Code are not met by your project and is a prerequisite to filing an appeal to the ZBA for zoning relief.
You will use the ZBA's online portal to file your appeal. You must file within 45 days of receiving your refusal letter from ISD. Please keep in mind that there is a $150 flat fee to file a zoning appeal. The Zoning Board will set up a public hearing date after your appeal has been processed, which you must attend.
Next Steps
Once you have secured the necessary permits, your next step is to begin construction on your ADU.
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Still have questions? Contact:
Housing
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12 Channel Street
9th FloorBoston, MA 02210
