Building permits, zoning and septic rules in St. Croix County, Wisconsin

Yes. New one- and two-family homes in St. Croix County must follow Wisconsin's statewide Uniform Dwelling Code¹. Construction may begin only after plans are approved and the building permit is issued and posted¹. The enforcing authority may be a municipality, county or state agency, and requirements for additions and alterations can vary by municipality¹. If the project uses private septic, obtain the sanitary permit before the local municipality can issue its building permit². Each construction phase must be inspected before the work is covered¹. An owner who occupies or will occupy the finished home may take out the construction and erosion-control permits, but owner-builder status does not remove code, inspection or other approval requirements¹.

Start with the town, village or city where the parcel lies for the building permit, because Wisconsin allows UDC enforcement by municipal or county inspectors or by the state¹. Inside New Richmond, the city issues residential building permits⁶. St. Croix County Community Development separately handles sanitary permits countywide and county zoning, shoreland, riverway and floodplain matters where those county rules apply; call 715-386-4680 or email cdd@sccwi.gov^3,7,8. County land-use applications require fees at filing, are generally non-refundable, and a late application can cost double the normal fee⁹. County land-use applications are due on the first Monday of the month, and staff strongly recommend a pre-application meeting⁷. Building-permit fees vary by municipality, so request the current requirements and fee schedule from the actual enforcing authority¹⁰.

St. Croix County general zoning covers all towns and unincorporated areas except Forest, Hudson, St. Joseph and Troy; county shoreland, floodplain, land-division, riverway and sanitary rules still apply across all townships^3,4. Cities and villages, including New Richmond, North Hudson, Roberts and the village of Baldwin, enforce their own zoning codes^4,11,12,13. We could not confirm separate zoning codes for the four excluded towns; ask the relevant town office before buying⁴. Where county zoning applies, Chapter 15 sorts land into base districts AG-1, AG-2, R-1, R-2, R-3, C-1, C-2, C-3, I-1, I-2 and CON, plus shoreland, Lower St. Croix Riverway, floodplain and non-metallic mining overlays, so the district decides what you can build¹⁴. Every dwelling, including a manufactured home, needs at least 500 square feet of floor area per family⁵. Minimum lot area and setbacks vary by district and design^3,14. Shoreland rules generally require a 75-foot setback from the ordinary high water mark, subject to exceptions and averaging¹⁵. Private septic approval stays with St. Croix County Community Development, including inside cities and villages^2,8.

A new private onsite wastewater treatment system needs a State Sanitary Permit, while repair, reconnection, rejuvenation or installation of non-plumbing sanitation needs a County Sanitary Permit². Only a licensed plumber may submit the sanitary application, the permit must precede the local building permit, and county staff inspect sanitary-permit work at least once². Private systems must also be serviced or inspected at least every three years unless a management plan says otherwise². A privy or composting toilet is therefore not a permit-free off-grid workaround². Only about 15% of county soils rate free of severe limits for a conventional drain field, so investigate soil and system feasibility before treating a lot as buildable¹⁶. St. Croix County Community Development administers POWTS permits and maintenance tracking; call 715-386-4680 or email cdd@sccwi.gov⁸.

Where county General Zoning applies, one camping unit on vacant land or beside a principal dwelling may generally be occupied or used for no more than 14 nights or days in a 60-day period⁵. A seasonal land-use permit can instead allow one camping unit on a vacant parcel from May 15 through September 15 if it has a state sanitary system and yearly sanitary reconnection permit; seasonal travel trailers are barred in major subdivisions⁵. During construction, a one-year land-use permit can allow a camping unit or manufactured home when the owner holds building and sanitary permits and connects it to a legal sanitary system⁵. Residential occupancy must stop when the principal home is capable of occupancy, and the manufactured home must be removed when the residence becomes occupied⁵. The county ordinance has no separate tiny-home category: a tiny home used as a dwelling must have at least 500 square feet per family⁵, while a portable structure that qualifies as a camping unit follows the camping limits⁵. County camping and dwelling-size provisions do not establish the answer for Forest, Hudson, St. Joseph, Troy or incorporated municipalities; ask the town or municipal zoning office^4,5.

1. Identify the parcel's zoning authority; county general zoning excludes Forest, Hudson, St. Joseph and Troy, while cities and villages use their own codes³.
2. Confirm the district's allowed use, minimum lot area, setbacks, height and utility requirements before finalizing the site plan^3,5,14.
3. Secure the required well approval if the home will use a private well¹.
4. Have a licensed plumber submit the county sanitary-permit application, because that sanitary permit must precede the local building permit².
5. File building plans, documents, fees and prerequisite approvals with the municipality or its authorized UDC inspection agency¹⁰.
6. Begin only after building-plan approval and building-permit issuance, then request each building inspection before covering the work¹.
7. Occupy after the final inspection finds no major health or safety violation; some municipalities also issue occupancy permits¹.

Confirm who zones the parcel first, because Forest, Hudson, St. Joseph and Troy fall outside county general zoning and every city or village enforces its own code; county sanitary rules and the county's township-wide land-division and overlay programs remain relevant³. If a seller proposes a new split, a survey and both town and county review may be required; creating 1-4 parcels within five years is a minor subdivision, while 5 or more is a major subdivision¹⁷. Check septic feasibility early because only about 15% of county soils rate free of severe limits for a conventional drain field¹⁶. Check flood maps before choosing a building site, because county-regulated floodplain development requires review and flood-resistant construction¹⁸. A driveway connecting to a state highway requires a WisDOT connection permit¹⁹. Renting a principal dwelling short-term requires an annual tourist rooming house license, locally issued by St. Croix County Public Health⁵.