Rock County, WI zoning map, flood zone and property lines by address
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Towns in Rock County: Janesville, Beloit, Milton.
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 Rock County has 182 FIRM panels, the newest effective September 2015; 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 Rock 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 Wisconsin statewide parcel layer (from each county, compiled by the State Cartographer), so a Rock lot shows the same lines the real property lister draws. Rock County covers about 459,627 acres of land and 5,114 acres of water.
Mapped lines are approximate. The Rock County real property lister keeps the parcel record (Rock County website); a licensed surveyor sets the true corners.
Zoning
In Wisconsin zoning is set by the county, the town or the city or village, depending on where the lot is: in Rock County, Janesville, Beloit, Milton 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 county, town or city zoning office has the district, the uses it allows and the lot size it needs. The Rock County website lists the county's municipalities.
ADU and guest houses
Under Wisconsin's zoning laws (Wis. Stat. 59.69 for counties, 60.61 for towns and 62.23 for cities), the county, the town or the city or village, depending on where the lot is can allow an accessory dwelling unit on a lot with a house. Whether a Rock lot can add one depends on its district; the county, town or city 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. Rock County is soil survey area WI105, Rock County, Wisconsin, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Rock County needs a permit from the Rock County sanitary permit office under the state POWTS rules (Department of Safety and Professional Services).
Setbacks
Setbacks in Rock County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county, town or city zoning office gives them for the lot's district, and Janesville, Beloit, Milton for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Rock lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Rock 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 Rock County has 182 panels, the newest effective September 2015. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Rock County?
Open the Wisconsin map, type the address, and the parcel outline from the Rock County real property lister 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 Rock County?
Zoning in Rock County is set by the county, the town or the city or village, depending on where the lot is (such as Janesville, Beloit). ParcelSheet shows the use code on the parcel record and names the municipality; the county, town or city zoning office has the final word.
Can I build an ADU in Rock County?
Under Wisconsin's zoning laws (Wis. Stat. 59.69 for counties, 60.61 for towns and 62.23 for cities), the county, the town or the city or village, depending on where the lot is can allow an accessory dwelling unit, and each sets its own rules. In Rock County ask the county, town or city 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 Rock County?
Yes. A new or changed septic system in Rock County needs a permit from the Rock County sanitary permit office under the state POWTS rules (Department of Safety and Professional Services). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area WI105 (Rock County, Wisconsin).
What can I build on 5 acres in Rock County?
Zoning in Rock County is set by the county, the town or the city or village, depending on where the lot is (such as Janesville, Beloit). 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 county, town or city zoning office has the district and its rules. See the Rock County website.
What are the residential setbacks in Rock County (2026)?
Setbacks in Rock 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 county, town or city zoning office gives them for the district. See the Rock County website.
Next to Rock County: Green County, Jefferson County, Walworth County.
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