Accessory Apartments

What is an accessory apartment?

An accessory apartment, sometimes called an in-law apartment, is a separate living unit located on a residential lot.  An accessory apartment includes one or more rooms used to provide living, sleeping, cooking, eating and sanitation, located within a single- or two-family dwelling or in a     detached structure on the same property. Accessory apartments are by definition subordinate in size and location to the primary unit.

How  do I know whether I can develop an accessory apartment?                        

Check with a building inspector. He or she can provide information about the City’s Accessory Apartment Ordinance (Section 6.7.1 of the Zoning Ordinance) and other regulations that may apply to your project, as well as other options that are available to you to help you achieve your goal.             

Is there a fee for review?

The fee is dependent on the type of permitting  process necessary for the accessory apartment, and are as follows:

Accessory Apartment Application  - building permit fee

Special Permit Application  -  $250.00 + $20 for required public notice sign + building permit fee (following special permit approval)

Can I legalize a pre-existing unit?

Yes.  All property owners with existing accessory apartments are encouraged to legalize existing units and to comply with building and life safety codes.

Is there funding available to help?

Funding assistance may be available to help homeowners offset the cost of improvements to make an existing accessory apartment legal or to construct a new apartment. Interested homeowners should contact the *Planning Department for additional information.

What Is The Process?     


Step 1

·Read the Accessory Apartment Ordinance (Chapter 30 Section 6.7.1 of the Zoning Ordinance) to learn about what you will need to ensure a successful project.

· Contact the Inspectional Services Department with any questions about creating an accessory apartment on your property.  Fill out the Pre-Application Form.

· Depending on the nature of your project, staff will direct you to a building permit or to any necessary reviews with Historic Planning, Urban Design Commission (as necessary), or Special Permit (if required).


Step 2  –  Permit Process.  Bring your plans to Inspectional Services Department for sign off. Then take the plans reviewed by the Fire Department, and Engineering Departments.  After review, apply for a building permit from ISD and complete building work.

Decision Making

Step  3  –  Upon completion of all reviews and approvals the Commissioner of ISD may issue a Determination Letter, authorizing the site for an accessory apartment.

Determination Letter

Step 4 - Bring building plans to the Inspectional Services Department (ISD) for review. Once it is determined that plans meet building code and Ordinance requirements, the applicant may receive a Determination Letter.

Step 5 - The Determination Letter must be recorded with the Registry of Deeds or Land Court and returned to ISD.

Step 6 - Certificate of Occupancy: After all work is completed and all final inspections the applicant must seek a Certificate of Occupancy.  After occupancy of the accessory unit, annual affidavits are required to be submitted to ISD.


Accessory Apartment Controls

¨ Only one apartment is allowed per lot and the minimum occupancy or rental term shall be 30 days.

¨ The property owner must occupy either the principal dwelling unit or the accessory apartment as their principal place of residence.

¨ The principal dwelling unit must have been constructed 4 or more years prior to the date of application for a building permit to create an accessory apartment.

¨ A Determination Letter granting pre-approval of the accessory apartment must be recorded at the Registry of Deeds or Land Court and an annual affidavit must be filed with the Commissioner of Inspectional Services., attesting to the continued owner occupancy of the property.

¨ The apartment size shall be:

à Internal Unit: a minimum of 250 sq. ft. and not more than 1,000 sq. ft. or 40% of the total building size of the structure, whichever is less;  or up to 1,200 sq. ft. by special permit.

à Detached Unit: permitted by special permit and a minimum of 250 sq. ft. and not more than 1,200 sq. ft. or 40% of the total building size of the structure, whichever is less; or up to 1,500 sq. ft. by special permit.

¨ Additional controls apply, please see the Accessory Apartment Ordinance (Chapter 30 Section 6.7.1 of Newton Zoning Ordinance).



Accessory Apartment Ordinance

Pre-Application for Accessory Apartment

Accessory Apartment Annual Affidavit

Archived 2017 Ordinance Updates



Inspectional Services                           617.796.1060

Planning Department                          617.796.1120

Fire Prevention                                     617.796.2210

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