Building permits, zoning and septic rules in Marathon County, Wisconsin

Wisconsin's Uniform Dwelling Code (UDC) applies statewide to new one- and two-family homes in Marathon County, including manufactured homes¹. The code covers new homes built since 1980 and specified additions and alterations; older homes, accessory structures and buildings with three or more residential units may fall under different rules, so ask the inspector before assuming a barn or shed is covered⁶. A UDC building permit is required for a new stick-built, modular or manufactured-home installation¹. Plans must be approved and the building permit issued and posted before construction begins; a new home on private septic also needs its sanitary permit before the building permit can be issued⁶. Required inspections cover footings, foundation and reinforcement, rough electrical, plumbing, HVAC and framing work, insulation, and final inspection¹. The inspector may be a delegated municipality's or a DSPS-appointed inspector, and the one named on the UDC permit is the person to notify¹. Request each inspection before covering the work; the inspector has 2 business days after the request and the work is ready to inspect before the work may be covered, subject to the local inspector's instructions⁶. Occupancy requires a final inspection with no major health or safety violations; some municipalities issue occupancy permits⁶.

A delegated town, village or city issues the UDC building permit and performs building inspections; where the municipality lacks delegated authority, submit the building-permit application to Wisconsin DSPS through eSLA and use its Inspector Look-Up Tool¹. The application must include plans, required data, contractor information where applicable and the building-permit fee¹. Building-permit authority does not change septic authority: Marathon County Conservation, Planning and Zoning (CPZ) handles septic permits countywide². For county zoning approval and septic permits, call CPZ at 715-261-6000 or cpz@marathoncounty.gov, at 1100 Lake View Drive, Suite 400, Wausau, WI 54403⁷. CPZ administers shoreland, floodplain, airport-overlay, POWTS and mining ordinances countywide, while general county zoning applies only after a town adopts it⁸. Cities and villages have separate zoning jurisdiction².

General county zoning applies to unincorporated Marathon County only in towns that adopted it². Inside Schofield and the Village of Rothschild, each municipality administers its own zoning; Marathon County CPZ remains the septic-permit authority^2,9,10. The county publishes district standards and maps for participating towns; use those maps to confirm where county zoning approval is required¹¹. In participating towns, minimum lot size, lot coverage, setbacks and building height depend on the district; shoreland or floodplain rules may also apply². A new or expanding manufactured-home park in the county's manufactured-home park district requires conditional-use approval and must satisfy park and lot standards². Shoreland, floodplain, airport-overlay and mining ordinances remain with CPZ even where general county zoning does not apply⁸. In an unincorporated shoreland area, buildings generally must be at least 75 feet from the ordinary high-water mark, subject to listed exceptions and setback averaging¹².

Marathon County CPZ administers the county private sewage system ordinance, while state POWTS requirements also apply². Every private sewage system needs its own application and sanitary permit before installation, replacement, repair, reconnection or modification; minor repairs are excepted¹³. A county sanitary permit is also required before constructing or installing a non-plumbing sanitation system¹³. POWTS construction and installation must be inspected under the plan-review approval letter; contact the agency that issued the permit when the system is ready¹⁴. Once a system is in service, state rule requires a visual inspection at least once every three years, and an anaerobic tank must be pumped when combined sludge and scum reach about a third of its volume⁴. Only about 11.6% of Marathon County soils are free of severe limitations for a conventional drain field, so obtain a site evaluation before assuming a standard field will work¹⁵.

On unincorporated parcels subject to Marathon County Chapter 17 zoning, RV use may be allowed for recreation, but permanent habitation is prohibited, and the ordinance passage we reviewed identifies no exception allowing it². Do not assume recreational use authorizes living in an RV while building; ask CPZ about the proposed use before relying on that arrangement^2,7. RV storage requires a principal structure in a Residential or Agricultural district; wetlands and some floodplain areas exclude RVs, and a compliant self-contained sanitary system or designated POWTS is required². Private/personal use is limited to 3 RVs per parcel unless the Zoning Administrator approves otherwise; parking longer than 180 days requires screening from the road right-of-way². Keep wheels attached except for repairs and do not fix the RV to the ground in a way that prevents immediate removal². Outside county-zoned towns, ask the applicable town, city or village about RV use². We could not confirm a countywide tiny-home occupancy rule; ask CPZ in a county-zoned town or the local municipality elsewhere⁷. In county-zoned towns, manufactured homes are allowed where single-family dwellings are allowed principal uses, subject to an 800-square-foot minimum and installation and design standards².

1. Use the county zoning maps or call CPZ to determine whether county or town zoning governs the parcel^7,11.

1. Obtain the applicable zoning approval before applying for the building permit⁶.

1. If the home will use private septic, obtain the county sanitary permit before construction and before the building permit; obtain any applicable well permit too^6,13.

1. Submit the building-permit application, contractor-license information, plans, required data and fee to the delegated local authority or DSPS¹.

1. An owner who occupies or will occupy the home may take out the construction and erosion-control permits, but the permits and code requirements still apply⁶.

1. Obtain driveway approval from the town for a town road, the Marathon County Highway Department for a county road, or WisDOT for a state or federal highway¹⁶.

1. Notify the inspector named on the UDC permit for the footings, foundation and reinforcement, rough work, insulation and final building inspections¹.

Confirm whether the town your parcel sits in has opted into Marathon County Zoning or zones itself; that changes who handles zoning, though CPZ remains the septic contact^7,17. Get a soils evaluation before you rely on a specific septic layout: only about 11.6% of Marathon County's soils are free of severe limitations for a conventional drain field, while 97.8% of the county's land has slopes of 15% or less¹⁵. If the parcel is near water, measure the 75-foot shoreland setback from the ordinary high-water mark before siting a structure¹². County shoreland and floodplain rules apply across unincorporated Marathon County, and town rules may be stricter¹¹. Check mapped floodway and floodfringe areas: floodway development is largely prohibited, and floodfringe structures need their first floor at least two feet above base flood elevation¹⁸. Confirm road ownership before planning access because the town, county Highway Department or WisDOT issues the driveway approval accordingly¹⁶. Land-division and addressing fees have their own county schedule; do not assume those figures cover building, zoning or septic permits¹⁹.