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Dennis, Massachusetts: what can you build or do?

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

Last reviewed 2026-10-15

• Accessory Dwelling Units (ADUs)
  Yes. Dennis allows one "Protected Use" ADU by right (building permit only) on a lot with an existing home in every zoning district except Industrial, as long as it is no larger than 900 sq ft or half the main home's floor area, whichever is smaller. On a lot with a protected ADU, neither the ADU nor the main house may be rented short-term: leases must be longer than 31 days. ADUs over 900 sq ft need a Planning Board special permit, must be inside or attached to the house, and carry owner-occupancy and 12-month lease rules.Allowed with a permit
• Backyard Chickens
  Yes, with a Board of Health poultry permit (renewed every January 1; fee capped at $5), under regulations dating from 2010. The rules conflict for smaller lots: a coop isn't allowed on a lot under 20,000 sq ft without a Board of Health variance, yet the same section lets those lots keep up to 12 birds, so owners of small lots should ask the Board about a variance first. Coops must be at least 10 feet from the abutter's line and 100 feet from wells and wetlands, and roosters over 16 weeks old aren't allowed on lots under 80,000 sq ft.Allowed with a permit
• Short-Term Rentals (Airbnb / VRBO)
  Yes, but you must first register with the Dennis Board of Health and get a Certificate of Registration, renewed every year (registrations expire March 15). Occupancy is capped at 2 guests per bedroom plus 2, your registration number must appear in every listing, and someone must be able to respond to emergencies within 1 hour. A by-right (protected) ADU can't be rented short-term at all.Allowed with a permit
• Fences
  South of Route 6, a typical fence needs no zoning approval: Dennis's zoning bylaw sets no fence height limit or setback (fences aren't "structures" under it), and its only fence rule is a corner-lot sight triangle (nothing over 2½ feet above street grade within 20 feet of the intersection). North of Route 6 you're in the Old King's Highway Historic District, where every fence needs a certificate from the Dennis OKH Committee; wooden fences 4 feet or lower in listed styles can get a certificate of exemption without a hearing, and others need full review.Depends on your zone
• Sheds & Accessory Buildings
  Yes, with paperwork. One shed of up to 200 sq ft and 15 ft tall may sit inside the normal setback areas as long as it is at least 2 feet from every lot line and not in front of the house, but it needs a Zoning Compliance Certificate from the Building Department. A larger or second accessory building must meet the district's full setbacks: for a single-family lot, 15 ft from the side and 25 ft from the rear in most districts, or 30 ft side and rear in R-60. North of Route 6, the Old King's Highway Committee must also approve the shed.Allowed with a permit
• Burn Permits & Backyard Fires
  Brush burning is allowed only in the January 15 to May 1 season, with a Dennis Fire Department permit (available online), between 10 a.m. and 4 p.m. on days the department allows, and at least 75 feet from buildings. Backyard fire pits need no permit if they're used mainly for cooking, smaller than 3 feet across and 2 feet high, at least 10 feet from structures, and attended; fire pits used just for ambiance are technically treated as open burning. Bonfires and fires on town property or beaches are not allowed.Allowed with a permit
• Home-Based Businesses
  Yes. A home occupation is allowed by right in every Dennis zoning district. It can be run by the residents plus no more than two non-resident employees, but it can't involve motor vehicle repair or selling goods mostly made elsewhere. You'll need 1 parking space per employee or per 400 sq ft of business space.Allowed
• Swimming Pools
  Dennis's zoning bylaw has no separate pool section. A residential pool appears to be treated as an accessory structure, so it would need to meet the district's setbacks (15 ft side and 25 ft rear in most districts, 30 ft side and rear in R-60), count toward lot coverage, and not sit in front of the house. You'll need a building permit and must meet the state pool-barrier rules; confirm the setbacks with the Building Department.Allowed with a permit
• Building Near the Water (Wetlands Rules)
  Work within 100 feet of a wetland, bank, beach, dune or marsh needs a Conservation Commission permit under the Dennis Wetlands Protection Bylaw. The Commission generally allows no new structures or alterations within 50 feet of a wetland resource area, except water-dependent projects like docks. Zoning separately bars structures within 50 feet of a coastal bank, mean high water, or the bank of a year-round stream or pond, again except docks, seawalls, walkways and similar.Allowed with board review
• Docks, Piers & Floats
  Possibly, with a Conservation Commission Order of Conditions plus state approvals. Dennis allows docks as water-dependent uses but won't permit new or bigger docks that would harm shellfish habitat. Docks need at least 3 feet of water at mean low tide without dredging, piers and walkways can be no wider than 4 feet and cross no more than 150 feet of marsh or flats, and floats can be no wider than 10 feet.Allowed with board review