Accessory Structures in Chelsea, MA (2026)
3 verified accessory structures rules for Chelsea, Massachusetts, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
ADUs are now allowed by right in Chelsea under Massachusetts Affordable Homes Act (Ch. 150, Acts of 2024, §8, effective Feb 2, 2025). Max 900 sq ft or 50% of principal dwelling. Chelsea's Planning Board was developing a local ADU ordinance in early 2025 to implement the state mandate, with design review retained.
Chelsea ADU (Accessory Dwelling Unit) Rules
Some RestrictionsM.G.L. c. 40A, § 3
No zoning ordinance or by-law shall prohibit, unreasonably restrict or require a special permit or other discretionary zoning approval for the use of land or structures for a single accessory dwelling unit, or the rental thereof, in a single-family residential zoning district; provided, that the use of land or structures for such accessory dwelling unit under this paragraph may be subject to re...
Shed & Carport Rules
Chelsea's zoning ordinance keeps accessory structures, including a tool shed, greenhouse or garage, out of the required front yard and at least five feet from any side or rear lot line unless the zoning board of appeals grants a special permit. A tool shed is a listed permitted accessory use in the R1, R2 and NHR residential districts under Sec. 34-50.
Chelsea Accessory Building & Shed Rules
Some RestrictionsChelsea Code of Ordinances § 34-50(c), (f)(5)
(c)Location. ... No accessory building, structure or use shall be located within the required front yard area nor shall be located nearer than five feet to any side or rear lot line except by special permit from the zoning board of appeals and conditional upon the following:(1)Adequate access on the lot shall remain for the unobstructed passage of emergency equipment to the rear of the principa...
Garage Conversions
Garage conversions to living space in Chelsea require a building permit and zoning compliance. Under the MA Affordable Homes Act (2025), garage conversions are one of the protected ADU types that must be allowed by right in single-family zones. Design review applies.
Chelsea Garage Conversion Rules
Some RestrictionsMGL c. 40A, §§ 1A & 3 (Affordable Homes Act)
The Affordable Homes Act, Section 7 and 8, amended M.G.L. Chapter 40A Section 1A and M.G.L. Chapter 40A Section 3 to allows accessory dwelling units — or ADUs — under 900 square feet to be built by-right in single-family zoning districts. An ADU must: Maintain a separate entrance, either directly from the outside or through an entry hall or corridor shared with the principal dwelling sufficient...