Accessory Structures in Waltham, MA (2026)
5 verified accessory structures rules for Waltham, Massachusetts, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Waltham must permit Accessory Dwelling Units by-right under the 2024 Massachusetts Affordable Homes Act (MGL c.40A s.3A). ADUs up to 900 sq ft are allowed on single-family lots without special permits.
Waltham ADU Rules
Few RestrictionsShed Rules
Sheds in Waltham under 200 square feet and 15 feet tall typically require no building permit but must meet zoning setbacks. Larger sheds need a building permit from the Building Department.
Waltham Shed Rules
Few RestrictionsGarage Conversions
Converting a garage to living space in Waltham requires a building permit, zoning compliance, and may now qualify as an ADU under the 2024 Massachusetts Affordable Homes Act.
Waltham Garage Conversion Rules
Some RestrictionsCarport Rules
Carports in Waltham require a building permit and must comply with zoning setbacks, lot coverage, and accessory structure rules. Most residential districts allow carports in side or rear yards only.
Waltham Carport Rules
Some RestrictionsTiny Homes
Tiny homes on foundations may qualify as ADUs in Waltham under the 2024 Affordable Homes Act. Tiny homes on wheels are treated as RVs and not allowed as permanent dwellings in residential zones.
Waltham Tiny Home Rules
Some RestrictionsLooking for Middlesex County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Waltham city rules.
Accessory Structures in Middlesex County →