ADU Permit Information
Everything you need to know about permitting your ADU project in Twin Falls, Idaho and the Magic Valley.
Zoning Use Permit for ADUs in Twin Falls
Before you can build an accessory dwelling unit in Twin Falls, you must obtain a Zoning Use Permit from the City of Twin Falls Planning & Zoning Department. ADU regulations are governed by the City's Uniform Development Code, specifically Title 10, Section 10-6-10-B (Accessory Dwelling Units) and Title 10, Section 10-6-10-A (Accessory Buildings). Any residential detached accessory building over 200 square feet requires a permit.
The Zoning Use Permit application is submitted to the City of Twin Falls Planning & Zoning office at 203 Main Ave E, Twin Falls, ID 83303 (P.O. Box 1907). You can reach the office by phone at (208) 735-7267 or by email at tfplanning@tfid.org.
Fees at a Glance
| Fee Type | Amount |
|---|---|
| ADU Zoning Use Permit | $250 |
| Residential Accessory Building Permit | $250 |
| Home Occupation Permit | $250 |
| All Other Zoning Use Permits | $500 |
| Building Permit | Varies by project valuation |
| Trade Permits (Electrical / Plumbing / HVAC) | Varies |
| Impact Fees | $6,000 -- $10,000 |
Refund policy: An 85% refund of the Zoning Use Permit fee is available if no staff review has been completed. A written withdrawal request is required.
Zoning Use Permit Submittal Requirements
Incomplete applications will not be accepted or scheduled for review.
- 1.Proof of Property Control -- one of the following: Deed, Executed Lease Agreement, Affidavit of Legal Interest, or Earnest Money Agreement signed by both buyer and seller.
- 2.Detailed documentation demonstrating full compliance with Title 10-6 -- all applicable zoning and development standards.
- 3.Written Project Description -- explaining reason for request, general compatibility with neighboring properties, and possible impacts. If applicable, include hours of operations, anticipated traffic, and number of employees. Attach a Site Plan and Photos.
- 4.Site Plan -- drawn to scale on 8.5" x 11" paper with: Measurement Scale, Property Lines, North Arrow, Street Names. Color elevations are required for all new buildings.
Application & Decision Process
Step 1: Contact Planning & Zoning
Call (208) 735-7267 or visit 203 Main Ave E in person to confirm zoning requirements for your property and proposed ADU. This is where our Feasibility Check provides major value -- we handle this research for you.
Step 2: Submit Complete Application
Submit the completed Zoning Use Permit application with all required attachments and fees ($250 for ADU projects). Incomplete applications will not be accepted or scheduled for review.
Step 3: Staff Review
City staff reviews your application and may request additional information or clarification. Experienced teams (like ours) minimize back-and-forth by submitting thorough documentation the first time.
Step 4: Staff Report & Analysis
Staff generates a report and analysis of the application with recommendations for approval, conditional approval, or denial.
Step 5: Written Decision
The applicant receives a signed written decision from the City on the Zoning Use Permit application.
Step 6: Appeal Period (15 Days)
Administrative decisions may be appealed to the Planning & Zoning Commission within 15 days of the written decision.
Step 7: P&Z Commission Hearing (If Appealed)
Upon appeal, the Planning & Zoning Commission schedules a public meeting and may uphold, conditionally uphold, or overrule the administrative decision.
ADU Development Standards
Per Title 10, Section 10-6-10-B of the City of Twin Falls Uniform Development Code, the following standards apply to all accessory dwelling units:
| Standard | Requirement |
|---|---|
| Eligible Lots | Any legal lot with a legal single household dwelling |
| Number per Lot | One ADU per lot |
| Maximum Size | 45% of the principal residence living space |
| Design Match | Must match existing roof pitch, siding, and windows of the principal dwelling |
| Parking | One additional off-street parking space required |
| Utilities | Must connect through the primary dwelling -- no separate meters allowed |
| Setbacks | Follow principal building setbacks for the applicable zoning district |
Detached Accessory Building Setbacks
Per Title 10, Section 10-6-10-A, setback requirements for detached accessory buildings depend on height and zoning district. Buildings under 200 sq ft, single story, under 15 ft tall, and used for storage only do not require a permit.
Buildings 15 ft tall or shorter (all zoning districts)
| Front Setback | Side Setback | Rear Setback |
|---|---|---|
| 20 ft | 3 ft | 3 ft |
Buildings taller than 15 ft (by zoning district)
| District | Front | Side | Rear | Max Height |
|---|---|---|---|---|
| TN-1 | 20 ft | 7 ft | 20 ft | 35 ft |
| TN-2 | 20 ft | 5 ft | 15 ft | 35 ft |
| TN-3 | 20 ft | 5 ft | 15 ft | 35 ft |
| All Others | 20 ft | 5 ft | 15 ft | 35 ft |
Idaho Law Protects Your Right to Build
Idaho House Bill 166 prevents jurisdictions from imposing an outright ban on accessory dwelling units. And as of July 1, 2023, HOAs cannot create or enforce rules that generally ban ADUs on detached, owner-occupied properties. Read our full regulations guide
Key Contacts
Twin Falls Planning & Zoning
203 Main Ave E, Twin Falls, ID 83303
Phone: (208) 735-7267
Email: tfplanning@tfid.org
For zoning questions, permit applications, and ADU compliance
Twin Falls Building Safety
203 Main Ave E, Twin Falls, ID 83303
Phone: (208) 735-7238
For building code and inspection questions
Downloadable Resources
Twin Falls Zoning Use Permit Application
PDFOfficial City of Twin Falls Zoning Use Permit Application form (updated February 2026). Required for all ADU projects.
Title 10: Zoning & Subdivision Regulations (2026)
PDFComplete City of Twin Falls Uniform Development Code -- Title 10. Contains all zoning districts, setbacks, height limits, lot coverage, and ADU regulations.
Chapter 03: Zoning Districts
PDFDetailed zoning district specifications for Twin Falls -- lot dimensions, building heights, setback tables, and permitted uses by district.
We Handle Permitting for You
Navigating permits is one of the most confusing parts of an ADU project. As part of our full-service approach, we handle every permit application, plan submission, and inspection coordination -- so you don't have to.
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