Unincorporated Twin Falls County building permits
VerifiedDepartment contacts, adopted codes, permit types, fees, and gotchas for Unincorporated Twin Falls County, Idaho.
Last verified 2026-07-08 · Source · Embed this page’s badge · Version history
Building department
- Address
- 630 Addison Avenue West, Suite 1100, Twin Falls, ID 83301
- Phone
- 208-734-9490
- Office hours
- Mon–Fri 8:00 AM – 5:00 PM (Building Department closed for lunch 12:30 PM – 1:30 PM)
- Website
- Official site
Inspection guide
See how inspections work in Unincorporated Twin Falls County — sequence, scheduling & re-inspection fees.
Codes adopted
Idaho adopts a statewide baseline building code set under the Idaho Building Code Act (Idaho Code Title 39, Chapter 41) and IDAPA rules administered by the Idaho Division of Occupational and Professional Licenses (DOPL). Effective January 1, 2021, the statewide baseline includes the 2018 International Building Code (IBC), 2020 Idaho Residential Code (based on the 2018 IRC Parts I–III and IX with Idaho amendments), 2020 Idaho Energy Conservation Code (based on the 2018 IECC with Idaho amendments), 2018 International Existing Building Code (IEBC), 2018 International Mechanical Code (IMC), 2018 International Fuel Gas Code (IFGC), and 2018 International Fire Code (IFC). The National Electrical Code is adopted separately by the Idaho Electrical Board (IDAPA 24.39.10), not bundled with the building code: Idaho enforces the 2023 NEC, effective July 1, 2024 (the state used the 2017 NEC with amendments before that and skipped the 2020 edition). Local jurisdictions must enforce the state baseline and may adopt amendments only where those amendments are at least as stringent as the state-adopted editions; local amendments may not be less restrictive. Enforcement is local — each city or county issues permits and performs inspections. Always confirm the current adopted edition and any local amendments with your specific jurisdiction before submitting plans.
- 2018 International Building Code (IBC) with Idaho Amendments
- 2018 International Residential Code (IRC) with Idaho Amendments
- 2018 International Energy Conservation Code (IECC) with Idaho Amendments
- 2018 International Mechanical Code (IMC) with Idaho Amendments
- 2018 International Fuel Gas Code (IFGC) with Idaho Amendments
- 2018 International Existing Building Code (IEBC) with Idaho Amendments
- 2018 International Fire Code (IFC) with Idaho Amendments
- 2018 Idaho Manufactured Home Installation Standards
Permit types & fees
Residential Building Permit (New Construction / Addition)
Required for new single-family dwellings, additions, garages, carports, covered decks/patios, and manufactured home placements in unincorporated Twin Falls County. Twin Falls County Community Development Services — Building Department reviews plans and issues permits under the 2018 IBC/IRC with Idaho Amendments. Applications may be submitted by email/upload or through the Citizens Connect permit portal.
Commercial Building Permit (New Construction / Tenant Improvement)
Required for new commercial buildings, tenant improvements, and change-of-use projects in unincorporated Twin Falls County. Governed by the 2018 International Building Code (IBC) with Idaho Amendments. A separate Commercial Plan Review Fee applies (65% of the building permit fee, or $200, whichever is greater). Applications submitted by email/upload or through the Citizens Connect permit portal.
Mechanical / HVAC Permit
Required for heating, ventilation, air conditioning, and fuel gas installations in unincorporated Twin Falls County. Unlike electrical and plumbing (which are administered statewide by the Idaho Division of Building Safety), Mechanical/HVAC permits in Twin Falls County are issued and inspected directly by the county's own Building Department under a locally-run program, using the county's own application and per-square-foot/per-item fee schedule.
Personal Use Energy Project Permit (Rooftop/Ground-Mount Solar)
Required for residential ('personal use') solar and wind energy systems in unincorporated Twin Falls County under Title 8, Chapter 21 (Energy Production) of the County Code, adopted March 2024. Per County Code Section 8-21-3(B): 'A siting permit and building permit is required prior to installation of any personal use energy project.' A personal-use project is a small system (per the ordinance's own drafting materials, capacity of 200 kW or less, footprint under 200 sq ft, associated with a single-family dwelling) — distinct from Small Scale (200 kW-10 MW) and Large Scale commercial energy projects, which instead require a Conditional Use Permit through the Planning & Zoning Division. The building-permit component is issued by the same Building Department and reviewed under the 2018 IBC/IRC as the county's general residential-building-permit; electrical interconnection work is permitted separately by the Idaho Division of Building Safety (state), not the county.
Electric Vehicle (EV) Charging Station / EVSE Permit
Unincorporated Twin Falls County does not itself issue electrical permits. Per the county's own building-permit documentation (confirmed on the paired solar-pv-permit entry in this file), electrical permitting and inspection -- which covers EV charging station/EVSE circuit installation -- is handled by the State of Idaho's electrical permitting program (Division of Occupational and Professional Licenses, Electrical Bureau, formerly the Division of Building Safety), not the Twin Falls County Building Department. No county-specific or state-published EV-charger/EVSE line item, distinct fee, or dedicated application was found; EVSE circuits are permitted as ordinary electrical work under the state's standard Electrical Permit Application.
New residential construction activity
New privately-owned residential construction onlyHousing units authorized by building permits for new privately-owned residential construction — this is not total permit volume (no commercial permits or remodels).
- Latest month (2026-05)
- 25units
25 buildings · $7.6M valuation
- Trailing 12 months
- 432units
12 of 12 months reported · #16 in Idaho coverage by units
- Year to date (2026 YTD through 2026-05)
- 177units
147 buildings · $46.4M valuation
- Full year 2025
- 527units
512 buildings · $158.7M valuation
County-wide figures: BPS reports county-wide totals; jurisdiction is the unincorporated remainder — county totals include the incorporated cities of Twin Falls, Buhl, Filer, Hansen, Hollister, Kimberly, Murtaugh, and Castleford
Source: U.S. Census Bureau, Building Permits Survey (BPS), 2026-05 vintage. Census survey data — separate from the permit-requirements verification above. All Idaho building activity
Tips & gotchas
- Twin Falls County adopted the 2018 IBC/IRC/IECC/IMC/IFGC/IEBC/IFC with Idaho Amendments, plus the 2018 Idaho Manufactured Home Installation Standards.
- Electrical and Plumbing permits for unincorporated Twin Falls County are issued by the Idaho Division of Building Safety (state), NOT the county — call 1-800-955-3044 or visit dbs.idaho.gov. Mechanical/HVAC is the exception: the county issues and inspects HVAC permits itself.
- Framing and Final building inspections cannot be scheduled until all required State of Idaho (electrical/plumbing/gas) rough-in or final inspections have been signed off on the construction card.
- Building permits expire 180 days from issuance or the date of the last inspection, whichever is later.
- Canyon rim setback is 100 feet — significantly stricter than typical property-line setbacks; check before siting any structure near a canyon rim.
- A FEMA Elevation Certificate is required before permit issuance (and again before final inspection) for any parcel within 100 feet of a major waterway.
- The residential Plan Review Fee (35% of building permit fee, $100 minimum) and the commercial Plan Review Fee (65% of building permit fee, $200 minimum) are both due at time of submittal and are non-refundable — separate from the building permit fee itself, which is collected at issuance.
- The county's only published plan-review turnaround estimate ('usually not more than seven business days') is explicitly scoped to residential projects in both the Residential and Commercial BP Information handouts — there is no distinct commercial or mechanical turnaround figure published anywhere, including in the FY2026 county budget (which has no Performance-Measures/KPI section for any department).
- Applications for building, manufactured home, demolition, and commercial permits require sign-off/comment letters from the South Central Public Health District (septic/well), the applicable Highway District, Canal Company, and Fire District — contact info for each is listed on the county's Building Applications Submittal Checklist.
- Accessory structures under 200 square feet accessory to a residence do not require a building permit; carports, garages, and any elevated deck (walking surface over 30 inches above grade) DO require one.
- If the parcel is within Castleford or Hollister city limits (surrounded by but distinct from unincorporated county land), an approval letter from that city is required in addition to county approval.
- Payments for zoning and building permit fees are made through the Citizens Connect online portal (twinfalls-id.permittrax.com); the county does not accept fee payment by mail per the Payments page.
- Twin Falls County Community Development Services is located at 630 Addison Avenue West, Suite 1100, Twin Falls, ID 83301. Building Department: Jon M. Laux, CFM — Director.