Home › Massachusetts › Cohasset

Cohasset, Massachusetts: what can you build or do?

Plain-English answers to common homeowner questions, taken from Cohasset's published bylaws, with every rule linked to the section it comes from.

Last reviewed 2026-10-05

• Accessory Dwelling Units (ADUs)
  Under the December 2024 zoning amendment, Cohasset allows one ADU per lot by right. It can be no bigger than 900 sq ft or half the main home's floor area, whichever is smaller, needs one extra off-street parking space (none near transit), and can't be used as a short-term rental. A larger ADU of up to 1,250 sq ft needs a special permit from the Zoning Board of Appeals, and the owner must live on the property.Allowed with a permit
• Backyard Chickens
  Under Cohasset's Board of Public Health animal regulations, you can keep up to 11 hens without a permit; 12 or more hens, or any rooster, needs a Keeping of Animals and Stable Permit. The regulations also say a coop must be at least 30 ft from property lines and 100 ft from any dwelling, well or wetland, which many smaller lots can't meet, so confirm with the Board how these setbacks apply to your flock.Restricted
• Burn Permits & Backyard Fires
  To burn brush in Cohasset you need a Residential Burn Permit from the Fire Department, issued online with an annual fee. Burning is allowed only from January 15 to May 1, and you must request each burn online on the day itself, between 9 a.m. and 2 p.m. The town's online permit system doesn't address backyard fire pits.Allowed with a permit
• Swimming Pools
  Under the Board of Public Health's pool regulations (adopted Sept. 20, 2022), you need the Board's approval of your plans before building any residential pool, and an inspection before using it. The pool must be enclosed by a fence at least 4 feet high with a self-latching gate, and kept at least 10 feet from a septic tank or the house foundation (20 feet from a cesspool or leaching field). We couldn't get Cohasset's zoning bylaw, so property-line setbacks are unknown; ask the Building Department.Allowed with a permit
• Building Near the Water (Wetlands Rules)
  Any building, filling, clearing or other alteration within 100 feet of a wetland, bank, pond, stream, estuary or tidal flood area in Cohasset needs a Conservation Commission permit under the town wetlands bylaw. The Commission's rules allow no alterations at all in the inner 50 feet unless it grants a variance.Allowed with board review
• Docks, Piers & Floats
  A private dock, pier or float in Cohasset needs Conservation Commission approval under the town wetlands bylaw. You must also show that state Chapter 91 and Army Corps permits have been applied for. Solid-fill docks are prohibited, and no new dock is allowed in an identified shellfish area. A float on a mooring in the harbor also needs a Harbor Master mooring permit.Allowed with board review

We couldn't download Cohasset's bylaw text for the other 4 topics yet, so we don't cover them rather than guess.