Zoning, building permits and septic rules in Union Township, Ohio

At a glance

Zoning

Yes, administered by Miami County Planning & Zoning, not the township¹

Building permit

Required for new homes in unincorporated Miami County; confirm coverage for your Union Township parcel²

Septic permit

Miami County Public Health³

New-dwelling zoning permit fee

$225⁴

RV or tent as a dwelling

Not allowed as the dwelling in R-1 residential districts⁵

Minimum home size

1,000 to 1,200 sq ft in R-1 districts, depending on the district⁶

Driveway permit

Miami County Engineer, or ODOT on a state route⁷

Owner-builder

Allowed; plans must be approved first⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Does Union Township, Ohio have zoning?

Yes. Union Township is zoned, but Miami County, not the township, administers the zoning program there¹.⁹ says the county department handles zoning for eight of the twelve townships, Union among them, so the Union Township zoning counter is the Miami County Planning & Zoning Department in Troy.

The county's published zoning resolution includes district and map articles, so the first step on any parcel is to look up its district on the official zoning map¹⁰. Unincorporated land in Union Township is also covered by the county's subdivision regulations, which matter if you plan to split a parcel¹¹.

For land outside the eight county-zoned townships, see the Miami County page.

What does Union Township zoning mean for RVs, tiny homes and home size?

In the R-1 single-family districts (R-1AAA, R-1AA, R-1A, R-1B and R-1C), a permitted one-family dwelling does not include a house trailer, mobile home, recreation vehicle or tent dwelling⁵. Living in an RV or tent as your home is therefore not allowed in those districts¹², and mobile homes are excluded there too¹³.

Minimum floor area for a dwelling in Union Township's R-1 districts is 1,200 square feet in R-1AAA, 1,100 in R-1AA and R-1A, and 1,000 in R-1B and R-1C⁶. Buildings in an R-1 district may not exceed 2-1/2 stories or 35 feet¹⁴.

We could not confirm rules for tiny homes, accessory dwellings, setbacks or minimum lot size, and we did not confirm what applies outside the single-family districts¹⁰. Ask Miami County Planning & Zoning for your parcel's district.

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

Miami County's Building Regulations department reviews and issues residential building permits for new construction in unincorporated areas under the Residential Code of Ohio². Its office is at 1506 One Stop Court, Suite 6, Troy, and the phone is (937) 440-8121¹⁵.

We could not confirm from an official source that this department's jurisdiction covers a specific Union Township parcel, so ask the department before you pour a foundation. A building permit is separate from the zoning permit: the zoning permit comes from Planning & Zoning and the building permit from Building Regulations.

Ohio's statewide residential and nonresidential codes apply where a certified building department has jurisdiction¹⁶. Owners building their own home must submit plans to that department and wait for approval before starting⁸.

How do septic permits work in Union Township?

Household sewage treatment systems in Miami County are permitted and regulated by Miami County Public Health, the local general health district³. The health district is at 510 W. Water St. Suite 130, Troy, and the phone is 937-573-3500¹⁷.

The county zoning permit application asks for a Health Department approval letter, so expect to deal with septic before zoning approval. We could not find a rule specific to Union Township, so confirm with the health district that its permit covers your parcel.

Soils matter. None of the soils we checked in Miami County are rated "not limited" for a conventional drain field¹⁸, so plan on a site evaluation and possibly a mound or other alternative system.

Building a home in Union Township: the steps, in order

1. Find your parcel's zoning district with Miami County Planning & Zoning⁹.
2. Get a septic site evaluation and approval letter from Miami County Public Health¹⁷.
3. Get a driveway permit from the Miami County Engineer, or from ODOT if the property is on a state route⁷.
4. Apply for the zoning permit; a new dwelling carries a $225 fee⁴.
5. Submit plans to Miami County Building Regulations for the building permit¹⁵.
6. If you want to divide the land first, check the county subdivision regulations¹¹.

What to check before you buy land in Union Township

Property taxes and values are county-level figures: Miami County's effective property tax rate is about 1% and the median bill is $2,106 a year¹⁹²⁰. Typical home value in the county is $273,782²¹.

Miami County is densely settled, with about 273 people per square mile, and the nearest city of 100,000 or more is about 14 miles from the county center²²²³. Land is gentle: 99.1% of the county is at 15% slope or less²⁴.

Flood risk: the Planning & Zoning Department also runs the county's floodplain management resolution for unincorporated land⁹. Short-term rentals, wells, and water or sewer connections are unconfirmed for Union Township, so ask the offices above.

Watch-outs

• Union Township's zoning is run by Miami County, so do not go to a township hall for zoning permits; use Miami County Planning & Zoning¹.
• We could not confirm whether the county building department covers every Union Township parcel; call (937) 440-8121 before you build¹⁵.
• The RV, tent and mobile home exclusions we confirmed apply to R-1 districts only; other districts may differ⁵.
• Wells, water and sewer connections, accessory dwellings and setbacks are unconfirmed for Union Township; ask Miami County Planning & Zoning and Miami County Public Health⁹.

Sources

1. Planning & Zoning | Miami County Ohio (Union Township), quoted and re-checked
2. Miami County Building Regulations (2026 county census)
3. Miami County Public Health (2026 county census)
4. Planning & Zoning Fee Schedule (Union Township), quoted and re-checked
5. Article 5 R-1 Single Family Residential District (Union Township), quoted and re-checked
6. Minimum Floor Area for Dwelling (Union Township), quoted and re-checked
7. What you will need when applying for a Zoning Permit (Union Township), quoted and re-checked
8. Section 3791.04 | Submission of plan - approvals - prohibition - fine (2026 county census)
9. Miami County Planning & Zoning (Department of Development) (miamicountyohio.gov)
10. Zoning Resolutions | Miami County Ohio (Union Township), quoted and re-checked
11. Planning & Zoning | Miami County Ohio (Union Township), quoted and re-checked
12. Article 5 R-1 Single Family Residential District (Union Township), quoted and re-checked
13. Article 5 R-1 Single Family Residential District (Union Township), quoted and re-checked
14. Article 5 R-1 Single Family Residential District (Union Township), quoted and re-checked
15. Miami County Building Regulations (Department of Development) (miamicountyohio.gov)
16. Section 3781.10 | Board of building standards - powers and duties (Ohio statewide rule), quoted and re-checked
17. Miami County Public Health - Environmental Health (miamicountyhealth.net)
18. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
19. Effective property tax rate: Bolthole Index county data
20. Median property tax bill: Bolthole Index county data
21. Typical home value (Zillow): Bolthole Index county data
22. Population density: Bolthole Index county data
23. Straight-line distance from the county center to the nearest city of 100,000+ people: Bolthole Index county data
24. Share of land at 15% slope or less: Bolthole Index county data

Written October 24, 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.