New Castle County, DE zoning map, flood zone and property lines by address
Free, no account. Or open the Delaware map and tap a lot.
Towns in New Castle County: Wilmington, Newark, Middletown.
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 New Castle County has 114 FIRM panels, the newest effective January 2020; 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 New Castle 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 Delaware FirstMap, statewide parcels from the three counties, so a New Castle lot shows the same lines the county assessment office draws. New Castle County covers about 272,856 acres of land and 43,321 acres of water.
Mapped lines are approximate. The New Castle County assessment office keeps the parcel record (New Castle County website); a licensed surveyor sets the true corners.
Zoning
New Castle County zones its unincorporated land, and Wilmington, Newark, Middletown each zone the land inside their limits. ParcelSheet shows the use the county assessment office lists for the lot and links the county planning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Delaware's county zoning laws (Delaware Code Title 9, Chapter 26 for New Castle, Chapter 49 for Kent, Chapter 69 for Sussex), local governments can allow an accessory dwelling unit on a lot with a house. Whether a New Castle lot can add one depends on its district; the county planning 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. New Castle County is soil survey area DE003, New Castle County, Delaware, last updated September 2026, on Web Soil Survey.
A new or changed septic system in New Castle County needs a permit from the Delaware Department of Natural Resources and Environmental Control (DNREC Division of Water, Groundwater Discharges Section).
Setbacks
Setbacks in New Castle County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county zoning office gives them for the lot's district, and Wilmington, Newark, Middletown for land inside their limits.
Hazards that apply
- Storm surge. New Castle 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 New Castle lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in New Castle 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 New Castle County has 114 panels, the newest effective January 2020. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in New Castle County?
Open the Delaware map, type the address, and the parcel outline from the New Castle County assessment office 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 New Castle County?
Zoning in New Castle County is set by the county for unincorporated land and by each city (such as Wilmington, Newark) inside its own limits. ParcelSheet shows the use code the county assessment office lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in New Castle County?
Under Delaware's county zoning laws (Delaware Code Title 9, Chapter 26 for New Castle, Chapter 49 for Kent, Chapter 69 for Sussex), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In New Castle County ask the 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 New Castle County?
Yes. A new or changed septic system in New Castle County needs a permit from the Delaware Department of Natural Resources and Environmental Control (DNREC Division of Water, Groundwater Discharges Section). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area DE003 (New Castle County, Delaware).
What can I build on 5 acres in New Castle County?
Zoning in New Castle County is set by the county for unincorporated land and each city inside its own limits (such as Wilmington, Newark). 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 planning office has the district and its rules. See the New Castle County website.
What are the residential setbacks in New Castle County (2026)?
Setbacks in New Castle County come from the zoning code of the county, or of the city when the lot is inside city limits: 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 zoning office gives them for the district. See the New Castle County website.
Next to New Castle County: Kent County.
The Delaware map · All Delaware counties · Flood zones explained · FIRM panels and LOMAs · All 50 states