Merrimack County, NH zoning map, flood zone and property lines by address
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Towns in Merrimack County: Concord, East Concord, Franklin.
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 Merrimack County has 179 FIRM panels, the newest effective January 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 Merrimack 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 Merrimack lot shows the same lines the town assessor draws. Merrimack County covers about 597,025 acres of land and 14,160 acres of water.
Mapped lines are approximate. The town assessors in Merrimack County keep the parcel record (Merrimack 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 Merrimack County, Concord, Franklin 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 Merrimack 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 Merrimack 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. Merrimack County is soil survey area NH609, Merrimack and Belknap Counties, New Hampshire, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Merrimack County needs a state construction approval from the New Hampshire Department of Environmental Services Subsurface Systems Bureau.
Setbacks
Setbacks in Merrimack 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 Concord and Franklin for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Merrimack lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Merrimack 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 Merrimack County has 179 panels, the newest effective January 2026. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Merrimack County?
Open the New Hampshire map, type the address, and the parcel outline from the town assessors in Merrimack 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 Merrimack County?
Zoning in Merrimack County is set by each town and city (such as Concord, Franklin), 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 Merrimack 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 Merrimack 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 Merrimack County?
Yes. A new or changed septic system in Merrimack 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 NH609 (Merrimack and Belknap Counties, New Hampshire).
What can I build on 5 acres in Merrimack County?
Zoning in Merrimack County is set by each town and city, not the county (such as Concord, Franklin). 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 Merrimack County website.
What are the residential setbacks in Merrimack County (2026)?
Setbacks in Merrimack 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 Merrimack County website.
Next to Merrimack County: Belknap County, Grafton County, Hillsborough County, Rockingham County, Strafford County, Sullivan County.
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