Bolthole Index

Boone County, Indiana

Zoning, building permits and septic rules in Thorntown, Indiana

The Town of Thorntown, Indiana (Boone County) zones all property inside town limits under its Unified Development Ordinance, and construction needs an improvement location permit from the town12. Living in an RV is not allowed outside an IDOH-approved campground or RV park3. Septic permits and well permits stay with the Boone County Health Department45.

At a glance

Zoning
Yes: town-wide under the Unified Development Ordinance1
Building permit
Improvement location permit required before construction2
Septic
Boone County Health Department; the Residential district requires town water and sewer46
RV living
Not allowed outside an approved campground or RV park3
Tiny home
Possible, but may need a variance from the minimum living area7
Minimum home size (R district)
1,000 sq ft of living area8
Minimum lot (R district)
6,000 sq ft and 50 ft wide9
Wells
Boone County well permit required5

Who to call

Zoning

Town of Thorntown Planning Administrator

Zoning and planning applications inside Thorntown, pre-application meetings and address assignment

463-201-8455

planning@thorntown.in.gov

101 W. Main St. Thorntown, IN 46071

Septic permits

Boone County Health Department - Environmental Health Division

Onsite sewage system permits and inspections, and well permits, in Boone County

765-483-4458

Boone County Office Building, 116 W. Washington St., Suite B202, Lebanon, IN 46052

Contact details are copied from each office’s official page and were checked against it on October 23, 2026.

Off-grid gear

Going off-grid in Town of Thorntown means bringing your own water and power. The kit we’d start with:

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Does Thorntown, Indiana have zoning?

Yes. The Town of Thorntown applies its Unified Development Ordinance and official zoning map to all property inside town limits1. The districts are Residential, High Density Residential, Public and Community, Downtown Business, Business and Light Industrial, plus a planned unit development district and a Flood Hazard Overlay10.

In the Residential district, a single-family home needs at least 1,000 square feet of living area8 and a lot at least 50 feet wide with 6,000 square feet of area9. Setbacks for a single-family home in the Residential district are 20 feet in front, 10 feet on the side and 10 feet in the rear, with 5 feet for accessory structures on the side and rear11. Impervious coverage tops out at 50% of the lot12, and primary structures can stand 35 feet high while accessory structures are limited to 25 feet13.

A tiny home may need a variance from the district's minimum living area7. Accessory dwelling units are allowed under the ordinance's own standards, and an approved accessory dwelling cannot be a short-term rental14.

Can you live in an RV in Thorntown?

No, not on a private lot. Thorntown's ordinance bars residential occupancy of a recreational vehicle outside a campground or RV park approved by the Indiana State Department of Health3. Recreational use only, with no permanent occupancy, is allowed for up to 14 consecutive days, twice per calendar year, and the administrator can prohibit serial stays15.

A manufactured home can serve as temporary housing for relatives, a caretaker, or the owner while a permanent dwelling is under construction. It must be tied down and removed within 30 days after the main building's certificate of occupancy is issued16.

Do you need a building permit in Thorntown, and who issues it?

Yes. Construction inside Thorntown requires an improvement location permit under the town's Unified Development Ordinance, and building without one brings a fine set in the fee schedule2. No permit or certificate of occupancy is issued for a building that does not conform to the ordinance17.

Start with the town's planning administrator, who offers a pre-application meeting by phone, email, video or in person18. Thorntown's rules apply inside town limits only; for land outside them, the Boone County Area Plan Commission handles unincorporated Boone County, as described on the Boone County page. We could not confirm the town's permit fee amounts, inspection steps or whether an owner may build their own home without extra requirements, so ask the planning administrator before you pay for plans.

How do septic permits work inside Thorntown?

Septic permits come from the Boone County Health Department, not the town. The county health department regulates, permits and inspects onsite sewage systems in Boone County4, and applicants submit an application and soil report to the Environmental Health Division19. The county lists an application, floor plans, a soil report, a plot plan and a fee as required20.

Many town lots will not need septic at all: the Residential district requires municipal water and sewer for new buildings6. Where sanitary sewers are not available, subdivision lots are routed to individual disposal systems under Boone County Health Department rules6. We could not confirm a septic rule for a single lot inside town, so ask the Health Department and the planning administrator which applies to a specific address.

What about wells and water?

A permit is required to drill or repair a well in Boone County, and the Boone County Health Department issues it5. The town's ordinance accepts an approved private well where public water is not available, and where public water lies within 300 feet of a proposed subdivision, the subdivider or water provider must extend mains6.

Building a home in Thorntown: the steps, in order

  1. Confirm the lot's zoning district on the town's official zoning map and read the district standards10.
  2. Schedule a pre-application meeting with the planning administrator18.
  3. Confirm water and sewer service; the Residential district requires municipal water and sewer6.
  4. If the lot is divided, a subdivision plat needs Plan Commission approval before lots are sold21.
  5. Obtain the improvement location permit before construction starts2.
  6. Get a certificate of occupancy once the building conforms to the ordinance17.

What stays with Boone County, and what to check before you buy in Thorntown

Septic permits and well permits stay with the Boone County Health Department45. Mapped flood areas in the town fall under a Flood Hazard Overlay district, though we could not confirm its permit rules10; the county's Area Plan administers floodplain permits only for unincorporated land22.

For cost context, Boone County's effective property tax rate is 0.8% and the median property tax bill is $2,725 a year2324. These are county figures, not Thorntown-only figures.

Watch-outs

  • Thorntown adopted its Unified Development Ordinance on May 4, 2026, replacing the earlier zoning and subdivision chapters, so older guides and listings may quote outdated rules1.
  • Lot, setback and size figures here are for the Residential district; the High Density Residential and Downtown Business districts use different standards8.
  • We could not confirm permit fees, inspection steps, driveway rules or well and septic requirements for a single lot inside town; ask the planning administrator at 463-201-8455 and the Boone County Health Department at 765-483-44581819.

Sources

  1. Town of Thorntown, Thorntown Unified Development Ordinance: notice of adoption (May 4, 2026) (Town of Thorntown), quoted and re-checked
  2. Town of Thorntown, Thorntown Unified Development Ordinance: notice of adoption (May 4, 2026) (Town of Thorntown), quoted and re-checked
  3. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  4. Waste Water - Boone County, Indiana, quoted and re-checked
  5. Water Wells - Boone County, Indiana, quoted and re-checked
  6. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  7. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  8. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  9. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  10. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  11. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  12. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  13. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  14. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  15. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  16. Thorntown Unified Development Ordinance, adopted text (20260504 version) (Town of Thorntown), quoted and re-checked
  17. Town of Thorntown, Thorntown Unified Development Ordinance: notice of adoption (May 4, 2026) (Town of Thorntown), quoted and re-checked
  18. Town of Thorntown Planning Administrator (townofthorntown.com)
  19. Boone County Health Department - Environmental Health Division (boonecounty.in.gov)
  20. Waste Water - Boone County, Indiana, quoted and re-checked
  21. Town of Thorntown, Thorntown Unified Development Ordinance: notice of adoption (May 4, 2026) (Town of Thorntown), quoted and re-checked
  22. Area Plan Commission - Boone County, Indiana, quoted and re-checked
  23. Effective property tax rate: Bolthole Index county data
  24. Median property tax bill: Bolthole Index county data

Written October 23, 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.

Answers from the rulebook for Town of Thorntown

Town of Thorntown’s own rules

  • Building permitRequired

    Construction of any building, structure or improvement inside Thorntown town under the UDO

    • The UDO names an improvement location permit (ILP) and other required permits; construction may proceed once the permit is obtained.
    • The UDO also states that a building permit is required to establish an accessory solar energy system (chapter 4, section b.10).
    • Fee and application details for the ILP were not located (see permit_fees).
    “any person or corporation who initiates construction prior to obtaining an ilp, certificate of occupancy, certificate of completion, or any other permit or authorization required herein, shall pay the fine as set forth in the fee schedule.”
  • Certificate of occupancyRequired

    Buildings, structures and improvements inside Thorntown town that need a certificate of occupancy

    • A certificate of occupancy is issued only where the location conforms to the UDO.
    • The notice does not describe the inspection steps for issuing a certificate of occupancy.
    “no ilp or certificate of occupancy shall be issued for any building, structure, or improvement unless the location of the building, structure, or improvement conforms to this udo.”
  • Local zoningPresent (with conditions)

    All property inside Thorntown town limits, under the Thorntown Unified Development Ordinance (UDO) adopted by Town Council Ordinance 2026-4 and the new official zoning map

    • Council voted to adopt Ordinance 2026-4 at its May 4, 2026 regular meeting; the notice states the UDO applies to all property within the town's jurisdiction.
    • The adopted UDO replaces the prior zoning and subdivision ordinances; the repeal list in Ordinance 2026-4 names the entirety of Chapters 151 and 152 (Land Usage) and the existing zoning map. The Ordinance 2026-4 copy located on the Town site is an unsigned draft with a blank date, so the adoption is taken from the Town's notice of adoption, not the draft.
    • Other claims in this record (dimensional standards, RV, manufactured and tiny home, ADU, subdivision) come from the adopted UDO text.
    “the udo and zoning map apply to all property within the jurisdiction of the town of thorntown.”
  • Zoning districtsPublished

    Zoning districts inside Thorntown town under the UDO

    • Districts shown in the adopted UDO text read: Residential (R), High Density Residential (HR), Public and Community (PC), Downtown Business (DB), Business (B), and Light Industrial (LI); the chapter 2 contents also list a Planned Unit Development (PUD) district and a Flood Hazard Overlay (FHO).
    • Dimensional tables for each district are in chapter 2; the Official Zoning Map was adopted with the UDO.
    “1. residential district (r). 2.4 2. high density residential district (hr). 2.6 3. public and community district (pc). 2.8 4. downtown business district (db). 2.10 5. business district (b). 2.12 6. light industrial district (li). 2.14 7. planned unit development (pud). 2.16”
  • Minimum dwelling sizeSpecified

    Single-family dwelling in the Residential district (R) inside Thorntown town

    • Minimum living area per single-family unit in R is 1,000 square feet, per the R district structure table.
    • High Density Residential (HR) and Downtown Business (DB) districts set a different single-family figure (800 square feet); they are not claimed here.

    minimum living area per single-family unit: >= 1000 sq ft (Residential district (R) only; tiny home variance may apply (see tiny_home_occupancy))

    “structure standards - residential district (r) primary structure accessory structure minimum living area per unit maximum height of structure single-family two-family and multiple-family non-residential 35 feet 25 feet 1000 sqft 35 feet 25 feet 1000 sqft/unit 35 feet 25 feet na”
  • Minimum lot sizeSpecified

    Single-family dwelling lot in the Residential district (R) inside Thorntown town

    • Minimum lot width 50 feet and minimum lot area 6,000 square feet per unit apply to the single-family row of the R lot table.
    • The two-family and multi-family rows of the R table differ (75 feet; 3,000 sq ft per unit and 6,000 sq ft respectively) and are not claimed here.
    • Values come from a flattened table; the row-to-use mapping is inferred from the column header order. Verify against the PDF table.

    minimum lot width: >= 50 feet (single-family, R district) · minimum lot area: >= 6000 sq ft per unit (single-family, R district)

    “lot standards - residential district (r) minimum lot width minimum lot area minimum front yard setback primary structure minimum side yard setback accessory structure primary structure minimum rear yard setback accessory structure maximum impervious surface coverage 50 feet 6,000 sqft/unit 20 feet 10 feet 5 feet 10 feet 5 feet 50% 75 feet 3,000 sqft/unit”
  • SetbacksSpecified

    Single-family dwelling and accessory structures in the Residential district (R) inside Thorntown town

    • Front yard 20 feet; side yard 10 feet primary and 5 feet accessory; rear yard 10 feet primary and 5 feet accessory.
    • Values come from a flattened table; the row-to-use mapping is inferred from the column header order. Verify against the PDF table.
    • Other district setbacks (HR, DB, B, LI) were not claimed.

    front yard setback, primary structure: >= 20 feet (R district, single-family) · side yard setback, primary structure: >= 10 feet (R district, single-family) · side yard setback, accessory structure: >= 5 feet (R district, single-family) · rear yard setback, primary structure: >= 10 feet (R district, single-family) · rear yard setback, accessory structure: >= 5 feet (R district, single-family)

    “lot standards - residential district (r) minimum lot width minimum lot area minimum front yard setback primary structure minimum side yard setback accessory structure primary structure minimum rear yard setback accessory structure maximum impervious surface coverage 50 feet 6,000 sqft/unit 20 feet 10 feet 5 feet 10 feet 5 feet 50% 75 feet 3,000 sqft/unit”
  • Lot coverageSpecified

    Single-family lot in the Residential district (R) inside Thorntown town

    • Maximum impervious surface coverage 50% for the single-family row of the R table.

    maximum impervious surface coverage: <= 50 percent of lot (R district, single-family)

    “lot standards - residential district (r) minimum lot width minimum lot area minimum front yard setback primary structure minimum side yard setback accessory structure primary structure minimum rear yard setback accessory structure maximum impervious surface coverage 50 feet 6,000 sqft/unit 20 feet 10 feet 5 feet 10 feet 5 feet 50% 75 feet 3,000 sqft/unit”
  • Building heightSpecified

    Primary and accessory structures in the Residential district (R) inside Thorntown town

    • Maximum height 35 feet for the primary structure and 25 feet for accessory structures in R.

    maximum height, primary structure: <= 35 feet (R district) · maximum height, accessory structure: <= 25 feet (R district)

    “structure standards - residential district (r) primary structure accessory structure minimum living area per unit maximum height of structure single-family two-family and multiple-family non-residential 35 feet 25 feet 1000 sqft 35 feet 25 feet 1000 sqft/unit 35 feet 25 feet na”
  • Living in an RVProhibited

    Use of a recreational vehicle as a residence on private land inside Thorntown town

    • Residential occupancy is allowed only in a campground or RV park approved by the Indiana State Department of Health (IDOH).
    • Recreational use outside a campground or RV park is allowed on the limits stated in the temporary_camping claim (14 consecutive days, twice per calendar year).
    “recreational vehicles are not permitted to be used for residential occupancy outside of a campground or an rv park approved by the indiana state department of health (idoh).”
  • Camping on your landLimited

    Recreational (non-residential) use of an RV on private land outside a campground or RV park inside Thorntown town; tent camping was not addressed in the text reviewed

    • The RV must be used for recreational purposes only, with no permanent occupancy.
    • Recreational use is limited to 14 consecutive days, twice per calendar year; serial occupancy is prohibited at the administrator's discretion.
    • Campgrounds and RV parks are a separate use with their own standards (chapter 4, section b.4); not read.

    recreational occupancy limit: <= 14 consecutive days (twice per calendar year; serial occupancy prohibited at administrator's discretion)

    “the rv is occupied for recreational purposes only (no permanent occupancy) and shall not exceed fourteen (14) consecutive days, twice per calendar year (serial occupancy is prohibited at the discretion of the administrator);”
  • Tiny homesLimited

    Establishing a single tiny home on a lot inside Thorntown town

    • A variance from the district minimum living-area requirement may be needed (Board of Zoning Appeals procedure, chapter 5, section d).
    • A tiny home development (more than one unit) follows the manufactured home park standards in chapter 4, section b.8 for general standards, operations and procedures; not read.
    “a variance from the minimum living area requirements for the subject district may be required to establish a tiny home.”
  • Manufactured homesLimited

    Occupancy of a manufactured home on a lot inside Thorntown town (temporary-use rule read; the general rule for permanent manufactured homes was not read)

    • The temporary-use rule covers occupancy by relatives, persons employed in the care of the property owner, or the owner while constructing a permanent dwelling.
    • The manufactured home must be tied down under the Indiana one- and two-family dwelling code.
    • The manufactured home must be removed within 30 days after the primary structure's certificate of occupancy is issued.
    • Manufactured home parks are a separate use (chapter 4, section b.8).

    removal deadline after primary structure certificate of occupancy: <= 30 days (temporary manufactured home rule)

    “the manufactured home must be removed from the property within thirty (30) days of the issuance of the primary structure’s certificate of occupancy.”
  • Accessory dwellingsLimited

    An accessory dwelling unit on a parcel that already has a primary residence, inside Thorntown town

    • Accessory dwelling units are regulated under chapter 4, section b.1 (general standards and district standards).
    • An approved accessory dwelling may not be used as a short-term rental.
    • District-specific size, placement, and owner-occupancy limits were not captured within budget.
    “it is the purpose of this section to regulate an accessory residential structure on a parcel where a primary residential structure exists”
  • Mandatory utility hookupWater and sewer (with conditions)

    New buildings on lots in the Residential district (R) inside Thorntown town

    • The R district utility table requires municipal water and sewer; the table gives no distance threshold for the district.
    • Subdivision rule: where a public water supply is within 300 feet of a proposed subdivision boundary, the subdivider and/or water provider must extend mains.
    • Where sanitary sewers are not available, the subdivision text routes lots to individual disposal systems under Boone County Health Department rules (see septic_authority).
    • Subdivision water rule also allows an approved private well where public water is not available (habitable buildings must connect to an approved water system, public provider or private well).

    public water distance threshold for subdivision extension: <= 300 feet (applies to proposed subdivisions only)

    “utility standards - residential district (r) municipal water and sewer required yes yes”
  • Subdividing landRegulated (with conditions)

    Division of land into lots inside Thorntown town, under the UDO subdivision chapters (6 to 8)

    • Subdivision plats require Plan Commission approval of a secondary plat, filed with the county recorder, before lots are sold or conveyed.
    • Subdivision must meet the water and individual disposal system standards in chapters 7 and 8, including Boone County Health Department soils and lot-area requirements.
    “no owner or agent of the owner of any parcel of the land located in a proposed subdivision shall transfer, sell, or convey any part of the parcel before a secondary plat of the subdivision has been approved by the pc in accordance with the provisions of these regulations and filed with the”
  • Short-term rentalsLimited

    Short-term rental of a dwelling inside Thorntown town

    • The UDO has a separate short-term rental standard (chapter 4, section b.9) and a short-term rental (owner occupied) use in the land-use matrix; the section was not read.
    • An accessory dwelling may not be used as a short-term rental.
    “each short-term rental unit shall be registered individually on an annual basis with the administrator in accordance with ic 36-1-24-11.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Town of Thorntown or Boone County directly.

  • Owner-builder exemption — Owner-builder construction of a home inside Thorntown town
  • Inspections — Inspections of new construction inside Thorntown town
  • Septic permit — Septic system permit for a home inside Thorntown town where sanitary sewer is not available
  • Septic inspection — Septic system inspection for a home inside Thorntown town
  • Off-grid sanitation — Off-grid sanitation (composting, privy, or other non-septic systems) inside Thorntown town
6 more unanswered
  • Well permit
  • Agricultural exemption
  • Driveway access
  • Building in a floodplain
  • Permit fees
  • Permit process

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Town of Thorntown publishes no rule on the point, not that none exists. Boone County’s page lists the county offices to call.

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