Zoning, building permits and septic rules in Millville, Utah

Millville’s own rules

• Building permitRequired

  Building or altering structures inside Millville city

  • Not applicable where retail cost of materials is under $1,000 (except structural changes) or for strictly cosmetic remodeling.
  • Accessory structures up to 200 sq ft need no permit unless state statute requires one (R-1, 17.20A.050).
  • Permit is issued by the county building inspector retained by the city.

  material cost exemption: < 1000 USD (structural changes)

  “this section shall not apply where either: a) the retail cost of materials used is less than one thousand dollars ($1,000.00), except for structural changes, or b) for strictly cosmetic remodeling.”

• Building code adoptedAdopted (with conditions)

  Construction inside Millville city

  • Code copy on the city site (uploaded 2018) adopts 1997 Uniform Building Code, 1999 National Electrical Code and 1997 Uniform Plumbing Code; it may be superseded by later state-mandated codes. Not confirmed as current.

  building code: 1997 Uniform Building Code

  “the entire 1997 edition of the uniform building code, including any amendments that have been or may be made by the uniform building codes commission and including the uniform building code standards, is adopted”

• InspectionsLimited

  Electrical installations inside Millville city; general building inspection by the county inspector not separately quoted

  • Electrical current may not be connected until inspection certificate issued.

  “upon completion of the installation of any electrical wiring, fixtures, appliances or apparatus in or on any building, it shall be the duty of the person doing the work to notify the building inspector who shall cause the same to be inspected”

• Local zoningPresent

  Land inside Millville city (Cache County), Utah

  • City code page lists 2025-2026 residential zoning amendments (ordinances 2025-5, 2025-7, 2026-1, 2026-5) that were not read; current text may differ from the cited chapters.

  “the city is divided into zones as shown on the map entitled zoning/city of millville”

• Zoning districtsPublished

  Zoning districts inside Millville city

  • Official zoning map is kept in the planning commission hearing room.
  • Later amendments (2025-2026) not read.

  districts: A, R-1, R-2, R-3, CG, OS, TC, HO overlay

  “r-2 single- and two-family residential zone (minimum 21,000 square foot lot size) r-3 single- and two-family residential zone (minimum 87,000 square foot lot size)”

• Minimum dwelling sizeSpecified

  Single-family dwellings in the R-1 zone inside Millville city

  • Calculated excluding basement, open porches, and garages.
  • Duplex units need 960 sq ft each.
  • R-2, R-3 and A zones not read.

  minimum finished living area: >= 960 sq ft (single-story dwelling)

  “the finished living area of any dwelling shall be a minimum of nine hundred sixty (960) square feet for a single-story dwelling.”

• Minimum lot sizeSpecified

  Single-family lots in the R-1 zone inside Millville city

  • Pending septic tank approval.
  • Larger minimums by slope class: 20,000 (class 2), 26,000 (class 3), 32,000 (class 4).
  • Minimum frontage 108 feet.
  • Zone chapter version dated 2023; later amendments not read.

  minimum lot area, slope class 1: >= 14000 sq ft · minimum frontage: >= 108 feet

  “lot area: minimum fourteen thousand (14,000) square feet for slope class 1 lots (see definitions in this title), pending septic tank approval.”

  One more reviewed finding on this topic

  • District specific (with conditions) — R-2 and R-3 residential zones inside Millville city

    “r-2 single- and two-family residential zone (minimum 21,000 square foot lot size) r-3 single- and two-family residential zone (minimum 87,000 square foot lot size)”

• SetbacksSpecified

  Main buildings in the R-1 zone inside Millville city

  • Interior lot side yard 15 ft; corner lot 15 ft interior side and 20 ft street side; corner lot rear 20 ft.
  • Accessory buildings: no minimum except drip line on the lot (2023 version); a 2025-2026 amendment reportedly sets 5 ft, not verified.
  • Corrals, barns and animal buildings must be 50 ft from a property line.

  front yard: >= 30 feet · rear yard, interior lot: >= 30 feet

  “front yard setback: minimum thirty feet (30') from the lot line.”

• Building heightSpecified

  Buildings in the R-1 zone inside Millville city

  • Other zones not read.

  maximum height: <= 35 feet

  “building height: 1. maximum thirty five feet (35'). 2. height shall be measured from the highest point of the building roof to the main entrance threshold.”

• Accessory dwellingsLimited

  Accessory dwelling units inside Millville city

  • One ADU per parcel.
  • Detached ADU under 50% of primary residence area and not over 1,200 sq ft; limited to 25% of rear lot area; not in front of primary dwelling; permanent concrete foundation.
  • Two extra off-street parking spaces; same address; no separate utility meters.
  • Rental requires a city rental permit.
  • Not permitted within a mobile home.
  • Penalty up to $50 per day.

  max external ADU size: <= 1200 sq ft (and under 50% of primary residence)

  “the owner of the property shall occupy either the adu or the primary dwelling where the adu is located as their place of primary residence”

• Subdividing landRegulated (with conditions)

  Subdivision of land inside Millville city

  • City code has a Title 16 (Subdivisions), not opened; ordinances 2025-1 and 2025-4 amended subdivision rules.

  “subdivisions on private lanes may be developed when the following conditions have been met”

• Short-term rentalsLimited

  Short-term rentals inside Millville city

  • Owner must reside in Millville city.
  • Business license required, not transferable.
  • Only within a permanent residential structure; no accessory structures, camping or RVs.
  • One short-term rental per property.
  • Off-street parking required.

  “short-term rentals are only allowed within a permanent, residential structure.”

• Permit feesVariable (with conditions)

  Building permits inside Millville city

  • No fee schedule amounts seen; fee is based on estimated construction value and collected with the permit by the building inspector; applicant also pays city fees to the city treasurer.

  “the building inspector shall collect a fee for the application of the actual building permit based on the estimated value of construction.”

• Permit processPublished (with conditions)

  Building permit applications inside Millville city

  • Planning commission must approve plans; applicant pays fees to city treasurer; the county building inspector retained by the city reviews plans and issues the permit.

  “a building permit clearance form shall be obtained from the planning commission secretary. the applicant will then contact the city development coordinator to review the project.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Millville or Cache County directly.

• Owner-builder exemption — Owner-builders inside Millville city
• Certificate of occupancy — Occupancy of new homes inside Millville city
• Lot coverage — Lots inside Millville city
• Living in an RV — RV occupancy inside Millville city
• Camping on your land — Camping inside Millville city

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.