Accessory Dwelling Units (ADUs)

Overview


Pursuant to Section 8 of Chapter 150 of the Acts of 2024, Accessory Dwelling Units (ADUs) under 900 square feet are allowed by-right in all zoning districts that allow single-family homes. An ADU is a is a small residential living space located on the same lot as another home. ADUs can be either internal within the existing primary structure on a site, external as an addition to the existing structure, or detached within a new or existing accessory structure on a site (such as a detached garage or carriage house).


Accessory_Dwelling_Unit_(ADU)_Types_1


Pursuant to state legislation, ADUs must:

  • Maintain a separate entrance, either directly from the exterior of the home, or through an entry hall or corridor shared with the principal dwelling sufficient to meet the requirements of the state building code for safe egress;
  • Be either no larger than half the gross floor area of the principal dwelling OR 900 square feet, whichever is smaller; and
  • Comply with local regulations, including, but not limited to, additional size restrictions and/or restrictions or prohibitions on short-term rentals.

For more information regarding the state legislation, please follow this link: Accessory Dwelling Unit (ADU) - FAQs | Mass.gov.

Additional guidelines for ADU construction in Lowell can be found below, or at this link. If you have any additional questions, please contact the Division of Development Services at 978-674-4144.

 

 

 

 

Accessory Dwelling Unit Definition 

 

 

“Protected Use ADU”. An attached or detached Accessory Dwelling Unit that is located, or is proposed to be located, on a lot in a Single-Family Residential Zoning District and no other Accessory Dwelling Unit is located on said Lot and which is protected from Prohibited Regulations and Unreasonable Regulations pursuant M.G.L. c.40A, S. 3, para. 11 and 760 CMR 71.00. 

 

 

 

What properties can CREATE an ADU? 

 

 

Any property located in a zoning district that allows single-family uses either by-right or by Special Permit is permitted one (1) ADU, regardless of the existing use of the property. 

 

ADUs are permitted in the following zoning districts: 

 

  • Suburban Single-Family (SSF)
  • Suburban Multi-Family (SMF)
  • Suburban Mixed-Use (SMU)
  • Traditional Single-Family (TSF)
  • Traditional Two-Family (TTF)
  • Traditional Multi-Family (TMF)
  • Traditional Mixed-Use (TMU)
  • Urban Single-Family (USF)
  • Urban Multi-Family (UMF)
  • Urban Mixed-Use (UMU)
  • Downtown Mixed-Use (DMU)

 

 

 

Maximum Size of ADUs 

 

 

The maximum size for an ADU is 900 square feet OR 50% of the Gross Floor Area of the Principal Dwelling, whichever is smaller. 

 

 

 

Internal ADUs 

 

 

 

Internal ADUs are located within the existing footprint for the structure where the footprint of the home remains unchanged, and no floor area is added to the home. 

 

 

 

Attached ADUs 

 

 

Attached ADUs are additions constructed to an existing structure to fully or partially accommodate an ADU. 

 

Attached ADUs must comply with all dimensional regulations pursuant to Section 5.1 of the Lowell Zoning Ordinance. 

 

 

 

Detached ADUs 

 

 

Detached ADUs are freestanding structures on the property utilized as an ADU. These may be located in existing detached structures or may be new structures built to serve as an ADU. 

 

Any newly constructed detached ADU or existing detached structure in which the footprint of the structure has been enlarged to accommodate an ADU must comply with the dimensional regulations for accessory structure pursuant to Section 4.3.5 and Section 4.4.1 of the Lowell Zoning Ordinance.  

 

Pre-existing, nonconforming accessory structures may be able to be converted into an ADU. Please consult with Division of Development Service (DDS) staff to confirm whether an existing accessory structure on your property may be converted into an ADU. 

 

 

Is parking required for an ADU? 

 

 

No off-street parking may be required for an ADU if the property is located within 0.5 miles of a Transit Station, including bus stops.  

 

 

Is owner-occupancy required? 

 

There is no owner-occupancy requirement for either the Principal Dwelling or ADU. 

 

 

 

Can an ADU be rented? 

 

 

ADUs may be rented, and there are no restrictions on who the property can be rented to.  

 

Please note that Short Term Rentals (STRs) are NOT allowed in the City of Lowell. All residential rental units must be rented for a minimum of thirty (30) days.