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

At a glance

Building permit

Required for new UDC dwellings before construction begins²

Zoning

County rules cover most unincorporated areas; four towns and incorporated places use other local authority⁴

Septic

A sanitary permit is required before the local building permit³

Owner-builder

Available to an owner who occupies or will occupy the home⁵

Seasonal camping

Limited to the permitted seasonal window and barred in major subdivisions⁶

Tiny home

No countywide occupancy answer confirmed; ask the zoning authority for the parcel⁴

Private well

Obtain the required well approval before building a home served by a private well⁷

Septic soils

Only about 15% of soils rate free of severe limits for a conventional drain field⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on September 29, 2026.

Do you need a building permit 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 posted². The enforcing authority may be a municipality, county or state agency, and requirements for additions and alterations can vary by municipality⁹. If the project uses private septic, obtain the sanitary permit before the local municipality can issue its building permit³. Each construction phase must be inspected before the work is covered¹⁰. 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 requirements⁵.

Who issues building permits in St. Croix County, and how do you reach them?

Start with the building authority for the town, village or city where the parcel lies, because Wisconsin allows UDC enforcement by municipal or county inspectors or by the state¹¹. St. Croix County Community Development handles county land-use and sanitary work from 1101 Carmichael Rd, Suite 1300, Hudson; call 715-386-4680 or email [email protected]¹²¹³. County applications require fees at filing, are generally non-refundable, and a late application can cost double the normal fee¹⁴. County land-use applications are due on the first Monday of the month, and staff strongly recommend a pre-application meeting¹⁵. Building-permit fees themselves vary by municipality, so request the current requirements and fee schedule from the actual enforcing authority before preparing plans¹⁶.

Does St. Croix County have zoning?

St. Croix County general zoning applies across its towns and unincorporated areas except the towns of Forest, Hudson, St. Joseph and Troy; cities and villages enforce their own zoning codes⁴. Confirm the parcel's governing authority before relying on a county district map, especially in an excluded town or incorporated place⁴. Within county jurisdiction, district rules control uses, yards, lot size and building height, so height is not one countywide number¹⁷. Shoreland rules generally require buildings and structures to sit at least 75 feet from the ordinary high water mark, subject to listed exceptions and setback averaging¹⁸. A floodplain development permit is required for covered work in county flood-prone areas, and the zoning administrator reviews those applications¹⁹. We could not confirm a countywide minimum dwelling size, accessory-dwelling rule or lot-coverage limit; ask the zoning authority that governs the parcel.

How do septic permits work in St. Croix County?

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 Permit³. Only a licensed plumber may submit the sanitary application, and the sanitary permit must be issued before the local building permit³. County staff conduct at least one inspection for all sanitary-permit work, and private systems must be serviced or inspected at least every three years unless a management plan says otherwise²⁰. A privy or composting toilet is therefore not a permit-free off-grid workaround²¹. 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 buildable⁸. St. Croix County Community Development administers POWTS permits and maintenance tracking; call 715-386-4680 or email [email protected]¹³.

Can you live in an RV or tiny home on your land in St. Croix County?

Seasonal placement of one camping unit on a vacant parcel requires a land-use permit, a state sanitary system and a yearly sanitary reconnection permit, and is allowed only from May 15 through September 15; seasonal travel trailers are not allowed in major subdivisions⁶. During construction, a parcel owner with valid building and sanitary permits may obtain a land-use permit for temporary occupancy of a camping unit or manufactured home connected to a legal sanitary system, and occupancy must end when the principal structure is complete²². We could not confirm a general countywide rule allowing full-time RV living or a specific tiny-home occupancy rule. Ask the zoning authority for the parcel, because county zoning excludes four towns and incorporated cities and villages administer their own codes⁴. A tiny home intended as a dwelling still needs an answer on building-code compliance, sanitation and the applicable district before placement¹²¹.

Building a home in St. Croix County: the steps, in order

1. Identify the parcel's zoning authority; county general zoning excludes the towns of Forest, Hudson, St. Joseph and Troy, while cities and villages use their own codes⁴.
2. Ask that authority about district use, setbacks, height and any floodplain permit before finalizing the site plan¹⁷¹⁹.
3. Secure the required well approval if the home will use a private well⁷.
4. Have a licensed plumber submit the sanitary application, because the sanitary permit must precede the local building permit³.
5. File the plans, documents, fees and prerequisite approvals with the municipality or its authorized UDC inspection agency²³.
6. Begin only after plan approval and permit issuance, then request each inspection before covering the work²¹⁰.
7. Occupy after the final inspection finds no major health or safety violation; some municipalities also issue occupancy permits²⁴.

What should you check before buying land in St. Croix County?

Confirm who zones the parcel first, because four towns fall outside county general zoning and every city or village enforces its own code⁴. 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 subdivision²⁵. Check septic feasibility early because only about 15% of county soils rate free of severe limits for a conventional drain field⁸. Determine whether public utilities are available or private systems are feasible; some development, including lower-density multifamily use in the R-3 district, requires municipal water and wastewater or a common treatment system²⁶. Check flood maps and permits before choosing a building site, because county-regulated floodplain development requires review and flood-resistant construction¹⁹. A driveway connecting to a state highway requires a WisDOT connection permit²⁷.

Watch-outs

• Do not assume the county zoning map controls every parcel: Forest, Hudson, St. Joseph and Troy are excluded from county general zoning, and cities and villages enforce their own codes⁴.
• A privy or composting toilet still requires a County Sanitary Permit, so off-grid sanitation is not permit-free²¹.
• Seasonal camping is limited to May 15 through September 15 with permits and an approved sanitary setup, and it is prohibited in major subdivisions⁶.

Sources

1. Wisconsin’s Uniform Dwelling Code, quoted and re-checked
2. Wisconsin’s Uniform Dwelling Code, quoted and re-checked
3. Sanitary Program, quoted and re-checked
4. Land Use and Zoning, quoted and re-checked
5. Wisconsin’s Uniform Dwelling Code, quoted and re-checked
6. St. Croix County Zoning Code, quoted and re-checked
7. Wisconsin’s Uniform Dwelling Code, quoted and re-checked
8. Share of soils without severe limits for a conventional septic drain field (USDA SSURGO): Bolthole Index county data
9. Wisconsin’s Uniform Dwelling Code (Wisconsin statewide rule), quoted and re-checked
10. Wisconsin’s Uniform Dwelling Code, quoted and re-checked
11. Wisconsin’s Uniform Dwelling Code (Wisconsin statewide rule), quoted and re-checked
12. St. Croix County Community Development Department (sccwi.gov)
13. St. Croix County Community Development Department (sccwi.gov)
14. CDD Fees & Policies, quoted and re-checked
15. Land Use and Zoning, quoted and re-checked
16. Wisconsin Administrative Code SPS 302.34 (Wisconsin statewide rule), quoted and re-checked
17. St. Croix County Zoning Code, quoted and re-checked
18. Wisconsin’s Shoreland Management Program (Wisconsin statewide rule), quoted and re-checked
19. Chapter 18 Floodplain Zoning, quoted and re-checked
20. Sanitary Program, quoted and re-checked
21. Sanitary Program, quoted and re-checked
22. St. Croix County Zoning Code, quoted and re-checked
23. Wisconsin Administrative Code SPS 320.09 (Wisconsin statewide rule), quoted and re-checked
24. Wisconsin’s Uniform Dwelling Code, quoted and re-checked
25. Land Division, quoted and re-checked
26. St. Croix County Zoning Code, quoted and re-checked
27. State highway connection permits (driveways & more) (Wisconsin statewide rule), quoted and re-checked

Written September 29, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.