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Barnstable, Massachusetts: what can you build or do?

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

Last reviewed 2026-10-04

• Accessory Dwelling Units (ADUs)
  Under the 2021 version of Barnstable's zoning ordinance we reviewed, one ADU per lot is allowed with a building permit from the Building Commissioner, either inside the house or in a detached accessory building. It can be no larger than 900 sq ft or half the main home's habitable floor area, whichever is smaller, with up to 2 bedrooms. The ordinance also requires that the ADU be used as a year-round rental (12-month minimum), but state law may override that.Allowed with a permit
• Short-Term Rentals (Airbnb / VRBO)
  Yes, but in the ordinance text we reviewed, Barnstable requires every rental, including short-term rentals, to be registered with the Board of Health before you rent or advertise it. The certificate costs $250 per unit and is renewed each December 31. Under the 2021 ADU zoning rules we reviewed, a home with an ADU, or the ADU itself, can only be rented for 12 months or more.Allowed with a permit
• Building Near the Water (Wetlands Rules)
  Almost any work within 100 feet of a wetland, pond, marsh, beach, coastal bank or flood-prone land needs a permit from the Barnstable Conservation Commission under the town's Wetlands Protection Ordinance (Ch. 237). The Commission's rules require keeping a 50-foot undisturbed natural buffer next to the resource area, and hardscape or landscaping closer than that needs a waiver plus 4:1 mitigation planting. The Commission's regulation also notes zoning construction setbacks of 35 feet from wetlands and 50 feet from mean high water, but we couldn't review the zoning ordinance itself.Allowed with board review
• Docks, Piers & Floats
  A private dock in Barnstable needs a Notice of Intent and approval from the Conservation Commission, which presumes docks are harmful unless you prove otherwise. Under the Commission's dock rules, floats are capped at 200 sq ft total, the walkway at 4 feet wide, and no dock may extend more than 100 feet past mean low water or more than half your water frontage. No new docks are allowed in an Area of Critical Environmental Concern (ACEC).Allowed with board review

We couldn't download Barnstable's bylaw text for the other 6 topics yet, so we don't cover them rather than guess.