Accessory Structures in Cambridge, MA (2026)
5 verified accessory structures rules for Cambridge, Massachusetts, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Cambridge allows accessory dwelling units by right under the 2024 MA Affordable Homes Act and MGL c.40A s.3A, the statewide ADU mandate. Most residential districts now permit one ADU by right.
Cambridge ADU Rules
Few RestrictionsMass. Gen. Laws ch. 40A, § 3 (Zoning Exemptions — Accessory Dwelling Units)
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 Rules
Cambridge requires a building permit for any shed over 120 sq ft and zoning compliance for smaller sheds. Setbacks of 3 to 5 feet apply, with extra review in historic districts.
Cambridge Shed Rules
Some RestrictionsGarage Conversions
Garage conversions to living space are permitted in Cambridge with full building permits. Under the 2024 MA Affordable Homes Act, converting a garage into an ADU is allowed by right in most zones.
Cambridge Garage Conversion Rules
Some RestrictionsCarport Rules
Carports in Cambridge are accessory structures subject to zoning setbacks and a building permit over 120 sq ft. They are uncommon on dense lots and historic districts often restrict open-wall designs.
Cambridge Carport Rules
Some RestrictionsTiny Homes
Tiny homes on foundations are allowed as ADUs in Cambridge under MGL c.40A s.3A. Tiny homes on wheels are treated as recreational vehicles and cannot be used as permanent dwellings under the MA State Building Code.
Cambridge Tiny Home Rules
Some RestrictionsLooking for Middlesex County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Cambridge city rules.
Accessory Structures in Middlesex County →