Frequently Asked Questions

Yes, but neither your home nor the ADU may be used as a short-term rental (example: AirBnB, VRBO)

1. An ADU is a small independent living unit on the same lot as a single-family home.  

• An ADU can be located WITHIN a single-family home such as in a lower level, 
• ATTACHED to a single-family home (an addition), or 
• DETACHED from the main home  

No larger than 50% of the main home OR 900 square feet – whichever is smaller.

That depends on the size of the unit, the location on your property and other factors. The Building Inspector can provide more information.

There are no restrictions on who may live in any ADU or main residence. The number of people that can live in either is based on building, health and fire codes. 

Complete an application with the Randolph Building Department available HERE. 

Please see “Documents section". If you have a pre-existing unit that you want reviewed, please check the “pre-existing” box on the form. Otherwise, check the “new construction” box.

•The Town's ADU Ordinance may be found here: https://ecode360.com/13201817 

•The State’s ADU regulations may be found here: https://www.mass.gov/info-details/accessory-dwelling-units   

All ADU’s must meet the current state and local requirements.

If your unit was lawfully constructed before February 2025, it must have:

• Been granted a Special Permit by the Town;
• Have the Special Permit recorded at the Norfolk County Registry of Deeds; and,
• Received building permits and completed all required inspections.

Research recorded special permits on your property here: https://norfolkresearch.org/ 

Contact the Building Department at 781-961-0921 for information on inspections, permits, and other approvals that have been issued for your property.

If there is no proof that permits were obtained, the unit is not “pre-existing, non-conforming” and may not be legal.  To have it approved as a legal ADU, you will need to submit a building permit application together with architectural plans that show that the unit meets (or will meet) current code standards.  The Building Inspector will review the application and any available records, and conduct an inspection of your property.

When the Building Inspector checks the structure, some things that will be reviewed are the number of ways a resident can get into and out of the unit, plumbing, cooling/heating, and wiring. If any electrical or plumbing work was done already, the walls may have to be opened so the Inspector can see the work and make sure it meets all codes.

Yes, if an addition to the main home or a completely separate structure is being proposed. 

It depends on whether sprinklers are already installed in the main house and how close the house is to emergency access points for the Fire Department.

A main line for each utility will come to the property to support both units.   Then, the lines will be separated to serve the main residence and ADU.  Since the two units may be occupied by different households, an ADU must function independently of the principal dwelling unit in terms of all utilities.

The ADU will not have a separate Town-owned water or sewer meter.  The property owner may install a submeter to track water and other utility use in the ADU separately from the main unit.   The property owner will continue to be responsible for payment of all Town utilities for both units.

It’s possible.  They should be reviewed to determine whether they can serve the ADU and the main unit.   You may need to upgrade your existing system or add a new connection for an ADU at your own expense.  A flow test or pressure test may help you determine if your existing system can serve both units. 

For information on Water/Sewer systems, contact the Town's Department of Public Works (DPW) at 781-961-0940 and the Town’s Engineering Department at 781-961-0950

Yes. Every dwelling unit needs to have a unique address for identification and safety purposes. The address number is assigned by the Engineering Department upon approval of construction plans.  It is shared with all Town Departments, the postal service and other organizations. When you prepare your application for a building permit, use the address of the existing home on the property.

It is possible. The construction of an ADU is considered an improvement to your property. The Town’s Assessor reviews each parcel to determine its value.  The property tax bill for the parcel is sent to the property owner of that whole parcel that includes ALL structures. That person is responsible for the full property tax bill.

Yes, both are required for the ADU. The property will have a trash fee for the main residence AND a trash fee for the ADU.

There are currently no grant or loan programs available.