Accessory Dwelling Unit (ADU) in Unincorporated Cache County, Utah
Required for construction of a secondary dwelling unit on a residential property in Unincorporated Cache County, including basement apartments, detached cottages, and garage conversions.
Verified 2026-06-27 · Source
When you need this permit
- Property zoned for ADU use (check {city} zoning map)
- Owner-occupancy of primary or accessory unit (varies by city)
- Maximum size limits (typically 50-65% of primary dwelling or 1,000 sq ft)
- Adequate parking (typically one additional off-street space)
- Separate entrance from primary dwelling
Required documents
- Req
Building Plans
Full construction drawings including floor plan, elevations, and sections
- Req
Site Plan
Property layout showing both units, setbacks, parking, and access
- Req
Zoning Compliance Letter
Verification that the property qualifies for an ADU under {city} zoning code
- Req
Fire Separation Details
1-hour fire separation between units if attached/internal
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Building Permit | Valuation-based per ICC table (typically $1,500-$4,000) | — |
| Plan Review | 65% of building permit fee | — |
| Impact Fees | Varies — often reduced or waived for ADUs in Utah | — |
Review timeline
~14–30 business days
Typical estimate — confirm current times with the Unincorporated Cache County building department
Inspection process
- 1
Foundation
Footings, forms, rebar — before concrete pour
- 2
Framing
Structure, fire separation, egress windows
- 3
MEP Rough-In
Mechanical, electrical, plumbing rough-ins before walls closed
- 4
Insulation
Insulation and vapor barrier before drywall
- 5
Final
All work complete, smoke/CO detectors, address posted, ready for occupancy
Tips
- Utah HB 82 (2021) requires most cities to allow at least internal ADUs — but Unincorporated Cache County may have additional local rules.
- Basement apartments in Unincorporated Cache County must have egress windows in every bedroom (5.7 sq ft minimum opening).
- ADU impact fees in Utah are often reduced or waived — ask Unincorporated Cache County about current fee schedules.
- A rental business license from Unincorporated Cache County is typically required before renting an ADU.
Frequently asked questions
- Can I build an ADU in Unincorporated Cache County?
- Most likely yes. Utah state law (HB 82) requires cities to allow internal ADUs. Unincorporated Cache County may also allow detached ADUs depending on zoning. Contact Unincorporated Cache County planning department to confirm your property qualifies.
- How much does an ADU permit cost in Unincorporated Cache County?
- ADU permits in Unincorporated Cache County are valuation-based and typically run $1,500-$4,000 for the building permit plus plan review (65% of permit fee). Impact fees may be reduced or waived under Utah state law.
Sources & verification
Key facts verified against official sources. Last reviewed 2026-06-27.
- Cache County Development Services — official building department
- Cache County Building Fee Schedule (Ord. 2024-18)
Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Unincorporated Cache County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
Other permits in Unincorporated Cache County
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