Twin Falls building permits

Tips & gotchas

• The City of Twin Falls Building Safety Department (203 Main Avenue East, 2nd Floor of City Hall) is a SEPARATE building program from Twin Falls County Community Development Services (630 Addison Avenue West, Ste 1100) — the City issues and inspects permits within Twin Falls city limits; the County's building department (twinfallscounty.org) governs unincorporated Twin Falls County and has its own separate application set. This jurisdiction file covers the CITY of Twin Falls program only.
• The City of Twin Falls has assumed local jurisdiction for building, electrical, plumbing, and mechanical permitting and inspection within city limits (each trade has its own dedicated City inspection phone line). Idaho DOPL separately registers/licenses contractors statewide but is not the permit-issuing or inspecting authority inside Twin Falls city limits.
• Idaho Building Code Act (Idaho Code Title 39, Chapter 41) establishes a statewide baseline: the 2018 IBC and 2018 IRC (Parts I-III and IX) with Idaho amendments must be adopted by any local government that issues permits and enforces building codes; local jurisdictions cannot adopt IRC/IECC residential provisions newer than what the Idaho Building Code Board has approved. Twin Falls administers 2018 IRC (Parts I-VI and IX plus Appendices A, B, G), 2018 IBC, 2018 IECC, 2023 NEC, and the 2017 Idaho State Plumbing Code, all with Idaho/local amendments.
• Published plan review timelines (City of Twin Falls Building Applications & Forms page, subject to workload/complexity): Commercial new complete buildings, additions, tenant improvements, and multi-family = 5 weeks to first review; Commercial miscellaneous (signs, pools, fences) = 3 weeks; Mechanical plan review = 3 weeks; Residential fences, decks, pools, and new single-family = 2 weeks to first review.
• Effective October 1, 2024, plan review fees for all commercial, industrial, and multifamily projects are due at the time of permit application submission (plan review will not commence until paid); this requirement does not currently apply to single-family and duplex construction.
• Building permit valuation (project value) explicitly includes roofing, mechanical, electrical, plumbing, owner-supplied equipment, elevators, and fire-extinguishing systems, in addition to the base construction value — this is why there is no separate roofing fee line; re-roofing is fee-assessed on the standard valuation-based Building Permit Fee schedule.
• Fences 7 feet or under do not require a permit anywhere on a lot except within defined sight triangles (driveway, street-intersection, alley), where a 3-foot height cap applies regardless of the general threshold.
• Residential detached accessory structures (sheds, garages, carports, gazebos) over 200 square feet, and any pool over 24 inches deep, require a building permit and must be sited at least 10 feet from the house.
• Solar PV installations have a fast-tracked 'Expedited Permit Process' for qualifying small systems (13.44 kW or less, engineered mounting, listed components, roof pitch >2/12); ballasted systems are excluded from the expedited pathway.
• All permits expire 180 days from issuance or the date of the last inspection; reactivation fees may apply for expired permits.
• Re-inspection fees ($50.00) are only charged if an inspection has failed more than once for the same issue.
• Inspections requested through the CityWorks portal by 7:00 AM are scheduled same-day; phone requests made after midnight are scheduled for the next business day. Concrete/foundation inspections receive scheduling priority.
• No dedicated ADU (accessory dwelling unit) permit application, fee schedule, or checklist distinct from the standard Residential Detached Accessory Building Application was found on the City of Twin Falls Building Safety Department site as of this review; new accessory dwelling units are addressed within that application's smoke-detector interconnection requirement, but a separately published ADU permit type was not found.