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ADU Construction · Fremont County, Idaho
Permit required
In Idaho, a ADU Construction requires a building permit.
An accessory dwelling unit (ADU) always requires a building permit because it adds a habitable dwelling, including electrical, plumbing, mechanical permits and egress/zoning review. Plans are reviewed under the Statewide code (IRC 2024); apply through Fremont County Annex Building before work begins.
Source: Statewide, IRC 2024 · Verified 2026 by StateDataIndex
Building an Accessory Dwelling Unit requires complex zoning, structural, and utility permits.
With a population of around 13,943 residents, Fremont County generally runs a more streamlined permitting process than major urban hubs.
Code Compliance & Inspections
Because of severe winter weather in Idaho, any exterior structures or footings must be set below the local frost line to prevent shifting, as mandated by the Idaho State Building Code.
Local Zoning & Setbacks in Fremont County
Regardless of the state permit rule above, Fremont County still enforces property-line setbacks and local zoning for your ADU Construction. A permanent foundation or any electrical/plumbing hookup can also change what is required, so confirm with Fremont County Annex Building before building.
Zoning & Cost Factors
Idaho generally favors property rights with relaxed state-level oversight, meaning agricultural zoning often dominates outside of major hubs like Boise. Fortunately, Idaho maintains relatively builder-friendly regulations, keeping base permit fees competitive.
Permit fees in Fremont County
Permit fees vary by jurisdiction and by your project's valuation, so there is no single fixed figure for Fremont County. We only publish fees confirmed by real homeowners — none have been reported here yet.
Confirm the current fee directly with Fremont County Annex Building ((208) 624-4643). If you have paid for a permit here, you can add it here to help others.
Fremont County Building Department
Office: Fremont County Annex Building
Address: 125 N Bridge St, St Anthony, ID 83445, USA
Phone: (208) 624-4643
Source: official Fremont County government records. Hours and procedures can change — call ahead to confirm.
How to Apply in Fremont County
In Fremont County, you or your contractor typically submit blueprints and a property survey to the local building department. Call ahead to confirm hours and accepted payment methods.
ADU Construction Requirements in Fremont County
Typical Submittal Package
When applying for a ADU Construction permit, you or your contractor will generally need to submit the following documentation for the city's review:
- Comprehensive architectural and structural plans
- Foundation engineering reports
- Sewer, water, and utility connection plans
- Site plan showing property lines and setbacks
Standard Ordinances & Processing Time
Key code points for a ADU Construction in Fremont County: ADUs typically have maximum square footage limits (often 800-1200 sq ft), height restrictions, and usually require dedicated off-street parking depending on local zoning.
Typical processing time for a jurisdiction of this size: 1 to 5 business days (Often over-the-counter).
Frequently Asked Questions
What happens if I build a ADU Construction without a permit in Fremont County?
Building without authorization is considered a code violation. The local government can issue a Stop Work Order, forcing you to halt construction immediately. You may be subject to retroactive permit fees (often double the original cost), daily fines, or even a mandate to tear down the unpermitted work at your own expense.
Can a homeowner pull their own ADU Construction permit in Idaho?
Yes. Idaho generally allows property owners to act as their own general contractor under an Owner-Builder exemption. If you take this route, you assume full legal and financial liability and must ensure all work complies with the Idaho State Building Code.
How much does a ADU Construction permit cost in Fremont County?
Permit fees vary by jurisdiction and by your project's valuation, so Fremont County does not publish a single fixed figure. Confirm the exact fee with the local building department before applying.
How long does it take to get a ADU Construction permit in Fremont County?
Based on the size of Fremont County, the typical processing time is 1 to 5 business days (Often over-the-counter). Times vary with the season and the building department application volume.
Where do I apply for a ADU Construction permit in Fremont County?
You can apply through the Fremont County Annex Building or online via the county permit portal. For questions, call (208) 624-4643.
Help the Fremont County Community
Did you recently pay for a permit here? Anonymously share the fee to help our database stay accurate.
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Read GuideBuilding It Yourself? Here's What You'll Need
Planning an ADU? Tools homeowners use in the design and layout phase:
📘
Backyard ADU Design Guide (Book)
View on Amazon →
📐
Laser Level
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🔍
Franklin ProSensor Stud Finder
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25ft Tape Measure
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Other Permit Types in Fremont County
Planning another home improvement project? Check the requirements and fees for:
Nearby Jurisdictions in Idaho
Building near the county line? Check requirements for neighboring areas: