Residential Addition / Interior Remodel Permit in Twin Falls, Idaho
VerifiedRequired for additions (enclosed and not-enclosed), interior remodels, and alterations to existing one- and two-family dwellings in Twin Falls. Reviewed against the 2018 IRC with Idaho amendments as locally administered by the City of Twin Falls. Separate application forms exist for enclosed additions, non-enclosed additions (e.g., covered patios/porches), and interior remodels.
Verified 2026-07-03 · Source
When you need this permit
- Building permit required for additions and alterations to existing structures, including sunrooms and interior remodels affecting structural or life-safety elements
- Use the Residential Addition Enclosed application for enclosed additions, the Residential Addition Not-Enclosed application for uncovered/open additions, or the Residential Interior Remodel application for interior work
- Plans designed to the 2018 IRC and IECC with Idaho amendments and City of Twin Falls residential Design Criteria
- Building permit valuation includes total project value (materials, labor, overhead and profit) for all work including any roofing, mechanical, electrical, and plumbing scope covered by the same permit
- Engineering required for walls over 10 feet or non-prescriptive designs
- Separate MEP permits required for any mechanical, electrical, or plumbing work
Required documents
- Optional
Residential Addition Enclosed Application
For enclosed additions to existing 1-2 family dwellings; submit via CityWorks portal or bsdpermits@tfid.org
- Optional
Residential Addition Not-Enclosed Application
For uncovered/non-enclosed additions such as open decks or patios
- Optional
Residential Interior Remodel Application
For interior remodels of existing 1-2 family dwellings
- Required
Construction Drawings
Site plan and framing/structural details showing scope of work and connection to the existing structure
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Building Permit Fee — valuation-based (same schedule as new construction) | $22.00 minimum ($1-$500 valuation), scaling up per the Master City-Wide Fee Schedule building permit table (e.g., $63.00 for the first $2,000 plus $12.50 per additional $1,000 up to $25,000) | City of Twin Falls Master City-Wide Fee Schedule |
| Residential Plan Review Fee | 30% of the building permit fee | City of Twin Falls Master City-Wide Fee Schedule |
| Re-inspection Fee | $50.00 | Charged only after an inspection has failed more than once for the same issue; City of Twin Falls Master City-Wide Fee Schedule |
Review timeline
10–10 business days
Twin Falls’s published plan-review target
Inspection process
- 1
Footing/Foundation
Required before concrete pour for addition footings; priority scheduling, AM or PM slot
- 2
Rough-In
Mechanical/electrical/plumbing rough-in and framing connections to the existing structure
- 3
Final
All work complete per approved plans; final MEP inspections signed off before building final
Tips
- Decks are reviewed under the 2-week residential plan review timeline published by the City.
- Use the Residential Detached Accessory application instead if the addition is a detached structure (garage, shed, detached deck) rather than an addition connected to the main dwelling.
- Additional permits (MEP) are required separately for any electrical, plumbing, or mechanical work tied to the addition/remodel.
Frequently asked questions
- Which application do I use for a deck or patio addition in Twin Falls?
- Use the Residential Addition Not-Enclosed application for an open/uncovered addition attached to the house, or the Residential Detached Accessory application if the deck is a separate, detached structure. Source: City of Twin Falls Building Applications & Forms page.
Sources & verification
Verified against official sources. Last reviewed 2026-07-03.
- City of Twin Falls Building Safety Department — official building department
- Building Applications & Forms | City of Twin Falls
- Residential Addition Enclosed Application (PDF) | City of Twin Falls
- Residential Addition Not-Enclosed Application (PDF) | City of Twin Falls
- Residential Interior Remodel Application (PDF) | City of Twin Falls
- Master City-Wide Fee Schedule (PDF) | City of Twin Falls
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 Twin Falls building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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