Building permits, zoning and septic rules in Fond du Lac County, Wisconsin

Yes. A UDC permit is required for a new one- or two-family dwelling in Fond du Lac County, including stick-built, modular and manufactured-home installations¹. Wisconsin's Uniform Dwelling Code governs one- and two-family homes, while the responsible permit authority may be the municipality or DSPS depending on delegated authority¹. The Town of Fond du Lac separately requires a building permit before a covered building or structure is erected, reconstructed, altered, moved or enlarged⁴. Required new-home inspections include footings, foundation and reinforcement, rough work, insulation and final inspection; the applicant must notify the inspector shown on the permit¹. An owner who occupies or will occupy the dwelling may use the owner-occupant route for construction and erosion-control permits, but that does not waive permits or code requirements⁷.

The correct permit counter depends on the parcel's municipality because zoning varies among Fond du Lac County's towns, villages and cities³. Start by identifying that municipality and its UDC inspection agency; where a municipality has delegated authority, apply locally, and otherwise DSPS handles the application¹. Fond du Lac County Planning & Development can help with parcel mapping and local contacts at 160 S. Macy Street, Fond du Lac, or (920) 929-3138¹⁰. County Code Enforcement handles county shoreland and floodplain questions at (920) 929-3140¹⁰. Permit fees vary by municipality, and the state permit-seal fee for each new dwelling is $30¹¹. In the Town of Fond du Lac, the written application goes to the Building Inspector, an approved permit must be displayed at the site, and the permit lasts 12 months unless substantial work begins⁴.

Fond du Lac County does not have countywide zoning: each of its 21 towns controls its own zoning ordinance and has its own permit issuer². Villages and the City of Fond du Lac also control their own zoning, and the county's GIS zoning layer is for reference only, so get zoning documents from the town, village or city³. County shoreland, floodplain, subdivision and sanitary rules may still apply³. Because the county sets no general zoning, it sets no countywide minimum dwelling size or tiny-home zoning rule either, but town or municipal ordinances may, and building-code, septic and other requirements still apply². In the Town of Fond du Lac, zoning districts have their own use and dimensional rules, and the official zoning map is available for inspection at Town Hall⁴. That town's code regulates minimum lots, yards and setbacks, lot coverage, building height and structure size, but the extracted rules do not supply a single numeric standard for every district⁴. In unincorporated shoreland areas, lots without sewer generally need at least 20,000 square feet and 100 feet of average width, while sewered lots generally need at least 10,000 square feet and 65 feet of average width⁸. Shoreland structures generally sit at least 75 feet from the ordinary high-water mark⁸.

Fond du Lac County is the sanitary-permit authority for private sewage systems, although a property served by public sewer may fall outside that requirement⁴. New construction served by a newly constructed POWTS needs a valid sanitary permit when the county land-use permit is issued, and other municipal, state or federal permits may also apply⁶. Contact the Fond du Lac County Code Enforcement Office's POWTS program at (920) 929-3139 before finalizing the building layout¹². Wisconsin also requires inspection of POWTS construction and installation under the plan-review approval, with the permitting agency as the inspection contact¹³. Only about 25.3% of the county's mapped soils rate free of severe limitations for a conventional drain field, so septic feasibility deserves attention before purchase¹⁴. Buildings with plumbing but no public-sewer connection must still provide for wastewater treatment, recycling, dispersal or holding under Wisconsin POWTS rules¹⁵. Wisconsin DSPS says installed systems must be visually inspected at least once every three years¹⁶. Fond du Lac County also assesses $13 a year to property owners with a private onsite wastewater system, starting with the 2025 tax year¹⁷.

We could not confirm one rule allowing long-term RV living or tiny-home occupancy on every private parcel in Fond du Lac County, and the county itself does not zone for either one². The county's own RV time limit applies only to its Columbia Park and Waupun County Park campgrounds, where no camping unit may stay more than 14 days in any four-week period¹⁸. The practical answer depends first on the parcel's town, village or city because local zoning varies across the county³. Ask the local zoning authority whether the proposed unit is a dwelling, a camping unit or an accessory structure, and ask what district, dimensional and occupancy rules apply. The Town of Fond du Lac, for example, uses district-specific rules and an official zoning map rather than one standard for every property⁴. A manufactured home used as a new dwelling is expressly within the state permit framework, but local land-use and sanitary requirements still apply¹. Fond du Lac County Planning & Development can help identify the correct municipality, but the local zoning authority should give the parcel-specific answer¹⁰.

1. Identify the parcel's town, village or city and confirm the zoning district, allowed use and dimensional standards with that municipality³.
2. If dividing land outside an incorporated area into a parcel of 35 acres or less, obtain Fond du Lac County Planning review and approval⁵.
3. Resolve county shoreland or floodplain conditions before fixing the building pad; prohibited work includes placing fill in a wetland or stream floodway⁶.
4. For a new POWTS, obtain the county sanitary permit alongside the county land-use permit⁶.
5. Obtain a Well Construction Notification Number before most new private-well construction⁹.
6. Submit the permit application, plans, required data and fee to the authority responsible for the parcel¹.
7. Call the inspector for each required phase, and occupy the home only after a final inspection finds no major health or safety violations^1,19.

Confirm the municipality and zoning district before making an offer because allowed uses and dimensional rules vary by town, village or city³. For unincorporated shoreland property, check lot area and width, the ordinary-high-water-mark setback and impervious coverage: coverage up to 15% is ordinarily allowed, while coverage above 15% and up to 30% requires mitigation⁸. Check mapped floodplain conditions before selecting a building pad because floodway development is tightly limited and new structures, wells and sewage systems are prohibited in the floodway²⁰. Test septic feasibility early because only about 25.3% of mapped soils lack severe limits for a conventional drain field¹⁴. Confirm access with the road authority; a driveway connection to a state highway requires a WisDOT permit²¹. For a private well, obtain the state notification number before most new construction⁹. A new private well that is not high-capacity needs advance notice to the Wisconsin DNR and a Well Construction Notification Number, with a $50.50 notification fee⁹.