Nantucket County, MA zoning map, flood zone and property lines by address
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Towns in Nantucket County: Nantucket.
Flood zone by address
ParcelSheet reads FEMA's National Flood Hazard Layer at the lot: the zone, whether it is a high risk area where lenders ask for flood insurance, and the base flood elevation where FEMA lists one. FEMA's countywide study for Nantucket County has 36 FIRM panels, the newest effective June 2014; coastal V zones, where waves add to the flood, are mapped along its shore.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Nantucket house comes from a licensed surveyor and is often on file with the county or city building office.
Property lines
The parcel outline, parcel number and mapped size come from the MassGIS, Property Tax Parcels from city and town assessors, so a Nantucket lot shows the same lines the town assessor draws. Nantucket County covers about 29,563 acres of land and 164,776 acres of water.
Mapped lines are approximate. The town assessors in Nantucket County keep the parcel record (Nantucket County website); a licensed surveyor sets the true corners.
Zoning
In Massachusetts zoning is set by each city and town, not by the county. ParcelSheet shows the use code on the lot's parcel record and the municipality it sits in; the town building or zoning office has the district, the uses it allows and the lot size it needs. The Nantucket County website lists the county's municipalities.
ADU and guest houses
Under Massachusetts's Zoning Act (General Laws Chapter 40A), each city and town can allow an accessory dwelling unit on a lot with a house. Whether a Nantucket lot can add one depends on its district; the town building or zoning office has the rule. ParcelSheet shows the mapped lot size and the ground's slope, the first two things the question turns on.
Septic and soil
ParcelSheet reads the USDA soil survey at the lot: the soil's name, its septic absorption rating and whether it is prime farmland. Nantucket County is soil survey area MA019, Nantucket County, Massachusetts, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Nantucket County needs a permit from the town or city board of health (under MassDEP Title 5 rules).
Setbacks
Setbacks in Nantucket County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the town building or zoning office gives them for the lot's district.
Hazards that apply
- Storm surge. Nantucket County has coastal V zones on its FEMA map, so storm surge reaches its shore. The county's evacuation zones are on its emergency management site; ParcelSheet shows the FEMA zone and the 3 ft sea level rise map at the lot.
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Nantucket lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Nantucket County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA's countywide flood map for Nantucket County has 36 panels, the newest effective June 2014. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Nantucket County?
Open the Massachusetts map, type the address, and the parcel outline from the town assessors in Nantucket County shows on the map with its parcel number and mapped size. Mapped lines are approximate; only a licensed surveyor sets the true corners.
What is my property zoned in Nantucket County?
Zoning in Nantucket County is set by each city and town, not by the county. ParcelSheet shows the use code on the parcel record and names the municipality; the town building or zoning office has the final word.
Can I build an ADU in Nantucket County?
Under Massachusetts's Zoning Act (General Laws Chapter 40A), each city and town can allow an accessory dwelling unit, and each sets its own rules. In Nantucket County ask the town building or zoning office for the lot's district first; ParcelSheet shows the lot size as mapped so you can see the room you have.
Do I need a septic permit in Nantucket County?
Yes. A new or changed septic system in Nantucket County needs a permit from the town or city board of health (under MassDEP Title 5 rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area MA019 (Nantucket County, Massachusetts).
What can I build on 5 acres in Nantucket County?
Zoning in Nantucket County is set by each city and town, not the county. The zoning district decides the uses, how many homes and the smallest lot it allows on 5 acres. ParcelSheet shows the lot size as mapped and the use code on the parcel record; the town building or zoning office has the district and its rules. See the Nantucket County website.
What are the residential setbacks in Nantucket County (2026)?
Setbacks in Nantucket County come from the zoning code of the municipality the lot sits in: the front, side and rear distances depend on the lot's district. ParcelSheet does not draw setback lines or give a number it did not read; the town building or zoning office gives them for the district. See the Nantucket County website.
Next to Nantucket County: Dukes County.
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