Hillsborough County, NH zoning map, flood zone and property lines by address
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Towns in Hillsborough County: Manchester, Nashua, Merrimack.
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 Hillsborough County has 233 FIRM panels, the newest effective June 2026; no coastal V zones are mapped in it.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Hillsborough 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 NH GRANIT parcel mosaic, from town parcel maps, so a Hillsborough lot shows the same lines the town assessor draws. Hillsborough County covers about 560,979 acres of land and 10,208 acres of water.
Mapped lines are approximate. The town assessors in Hillsborough County keep the parcel record (Hillsborough County website); a licensed surveyor sets the true corners.
Zoning
In New Hampshire zoning is set by each town and city, not by the county: in Hillsborough County, Manchester, Nashua each zone the land inside their limits. ParcelSheet shows the use code on the lot's parcel record and the municipality it sits in; the town planning and zoning office has the district, the uses it allows and the lot size it needs. The Hillsborough County website lists the county's municipalities.
ADU and guest houses
Under New Hampshire's municipal zoning law (RSA Chapter 674, starting at 674:16), each town and city can allow an accessory dwelling unit on a lot with a house. Whether a Hillsborough lot can add one depends on its district; the town planning and 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. Hillsborough County is soil survey area NH601, Hillsborough County, New Hampshire, Eastern Part, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Hillsborough County needs a state construction approval from the New Hampshire Department of Environmental Services Subsurface Systems Bureau.
Setbacks
Setbacks in Hillsborough County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the town planning and zoning office gives them for the lot's district, and Manchester and Nashua for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Hillsborough lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Hillsborough 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 Hillsborough County has 233 panels, the newest effective June 2026. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Hillsborough County?
Open the New Hampshire map, type the address, and the parcel outline from the town assessors in Hillsborough 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 Hillsborough County?
Zoning in Hillsborough County is set by each town and city (such as Manchester, Nashua), not by the county. ParcelSheet shows the use code on the parcel record and names the municipality; the town planning and zoning office has the final word.
Can I build an ADU in Hillsborough County?
Under New Hampshire's municipal zoning law (RSA Chapter 674, starting at 674:16), each town and city can allow an accessory dwelling unit, and each sets its own rules. In Hillsborough County ask the town planning and 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 Hillsborough County?
Yes. A new or changed septic system in Hillsborough County needs a state construction approval from the New Hampshire Department of Environmental Services Subsurface Systems Bureau. ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area NH601 (Hillsborough County, New Hampshire, Eastern Part).
What can I build on 5 acres in Hillsborough County?
Zoning in Hillsborough County is set by each town and city, not the county (such as Manchester, Nashua). 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 planning and zoning office has the district and its rules. See the Hillsborough County website.
What are the residential setbacks in Hillsborough County (2026)?
Setbacks in Hillsborough 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 planning and zoning office gives them for the district. See the Hillsborough County website.
Next to Hillsborough County: Cheshire County, Merrimack County, Rockingham County, Sullivan County.
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