Cambridge, Massachusetts: what can you build or do?
Plain-English answers to common homeowner questions, taken from Cambridge's published bylaws, with every rule linked to the section it comes from.
Last reviewed
Accessory Dwelling Units (ADUs) Yes. Cambridge's Zoning Ordinance permits Accessory Apartments in every zoning district where residences are allowed, with no special permit, and it sets no owner-occupancy rule or size cap. The local definition covers a unit inside a single- or two-family house; detached ADUs aren't addressed locally, but state law has protected one attached or detached ADU per lot since February 2, 2025.Allowed
Backyard Chickens Yes, with a permit from the Cambridge Public Health Department. You can keep up to 6 hens (up to 12 only if your permit explicitly allows it), roosters are banned, and the coop and run must be outside the front yard and at least 5 feet from property lines unless screened by a solid fence or wall.Allowed with a permit
Short-Term Rentals (Airbnb / VRBO) Only if Cambridge is your primary residence. You can rent rooms (up to 3 bedrooms) in the unit you live in, or a whole unit next to yours in a building of 4 or fewer units that you own entirely. You must register with Inspectional Services and pass an inspection before renting; the ordinance doesn't set the fee, and the only fee we found ($500, valid five years) is in a city guide dated November 2017, so confirm the current amount with ISD.Restricted
Fences Yes. Cambridge has no citywide fence height limit: its Zoning Ordinance allows fences in front, side and rear yards and doesn't cap their height outside a few overlay districts. In the Parkway Overlay (e.g. near Fresh Pond) and the Alewife Quadrangle, fences near the street can't exceed 4 feet or be more than 30% opaque, and chain-link is banned. Separately, the state building code requires a building permit for fences over 7 feet.Allowed
Sheds & Accessory Buildings A small shed is allowed, but it has to meet zoning at any size. The state building code exempts one-story storage sheds of 200 sq ft or less from a building permit, while the city's FAQ still says 120 sq ft, so check with Inspectional Services for a shed between 120 and 200 sq ft. In the Residence C-1 district, an accessory building can be at most 15 feet tall, must meet the district setbacks (10 ft front, 5 ft side/rear), and all accessory buildings and uses together can cover at most 15% of the lot.Allowed
Burn Permits & Backyard Fires No. In an August 2024 notice, the Cambridge Fire Department says open burning is prohibited in Cambridge, including fire pits, chimineas, outdoor fireplaces and burning yard waste, brush or trash. MassDEP also bans outdoor burning in Cambridge year-round, so there is no burn-permit season here.Not allowed
Home-Based Businesses Yes, as an accessory use with no special zoning approval, as long as only residents of the home work there (a resident professional may have up to 3 people practicing or employed on site), everything happens inside the building, and there's no offensive noise, smoke or other nuisance. In residence districts, no stock in trade, displays or signs beyond what Article 7 allows.Allowed
Swimming Pools Cambridge's Zoning Ordinance articles we reviewed don't have specific rules for residential swimming pools or hot tubs. The state building code still requires a building permit and a barrier at least 48 inches high, and the work must comply with zoning.Not specifically regulated
Building Near the Water (Wetlands Rules) Building near water in Cambridge is allowed but reviewed. Any work within 100 feet of a wetland, floodplain or water body such as Fresh Pond, the Charles River or Alewife Brook needs a permit from the Conservation Commission under the state Wetlands Protection Act. In FEMA flood zones (the Floodplain Overlay District) you also need a permit from the City Engineer, and a new building on a new foundation, or an addition with a new foundation that grows the footprint by 50% or more, must be certified to the city's flood resilience standards.Allowed with board review
Docks, Piers & Floats Cambridge's Zoning Ordinance doesn't regulate private docks, piers or floats. Any work in or next to Fresh Pond, the Charles River, Alewife Brook or other water bodies falls under the Conservation Commission and state law (Wetlands Protection Act and, where it applies, a Chapter 91 license).Not specifically regulated