County paperwork
The Fremont County permit path for a new house in Ashton
Published · every figure below was checked against its primary source on the date shown.
Start with the right form, not the right builder
The county opens a file; the builder fills it. A new house in unincorporated Fremont County runs through Fremont County Building Department, Fremont County Courthouse, 151 W 1st North, St. Anthony, ID 83445 — (208) 624-7200. Every document below was fetched and confirmed live on 13 August 2026.
| Document | What it is |
|---|---|
| Building Permit Application | The form that opens the file for every structure except a manufactured home. |
| Permission Letter to Build | 2026 revision (county PDF modified 22 May 2026) — the newest form in the set and the one most applicants have never seen. |
| Do I Need A Building Permit? | The county's own threshold sheet — read it before assuming a shop or an addition is exempt. |
| Snow Load Zone Map | Which district your lot sits in. Image-only, no searchable text. |
| Manufactured Homes | The separate path if the house arrives built. |
The sequence, in the order the county actually needs it
- Confirm the lot is buildable — access, and a septic site evaluation through Eastern Idaho Public Health. This runs before everything else, because it is the step that can produce a no.
- Confirm your snow-load district against the county’s Snow Load Zone Map, then hand that figure to your designer.
- Get plans drawn and engineered to that ground snow load and to the 32-inch minimum frost depth.
- Submit the Building Permit Application with the plan set, and ask the department whether the 2026-revised Permission Letter to Build belongs in your file.
- Schedule inspections as the work reaches them — the file stays open until the county closes it, not until the house looks finished.
The two figures the plan set has to satisfy
“Section 3. Ground Snow Load: The ground snow load shall be … 90 PSF. for the Ashton District…”
“Section 4. Minimum Frost Depth for Footings: The minimum frost depth for footings shall be 32 inches.”
— Fremont County Ordinance No. 2005-02, Sections 3 and 4 (county-published PDF, retrieved 13 August 2026)
These are minimums rather than recommendations, and the distinction matters more than it sounds — the state’s own engineering reference suggests a higher ground snow load for Ashton, Drummond and Warm River than the district figure sets.
What trips corridor applicants most often
- Assuming a shop or a barn is exempt. The county publishes a threshold sheet precisely because the assumption is common and frequently wrong.
- Treating the septic file as a formality. It is a separate agency, a separate clock, and a seasonal one.
- Designing before confirming the district. Re-engineering a roof after plans are drawn is the expensive way to learn a zone boundary.
- Forgetting the energy code. The adopted 2018 IECC governs insulation and glazing performance, and it is part of the same file.
- Leaving “who pulls the permit” unsaid in the bid.
Where this page stops
Permit decisions belong to the county building department, and nothing here substitutes for calling them on (208) 624-7200 with your parcel in front of you. What this page is for is arriving at that call already knowing which form starts the file and which two numbers the plans have to satisfy.
Related reading on this site
- The 90 PSF question — why the county figure and the state study disagree
- Well and septic diligence — the step that has to clear before the file can
- The 32-inch frost depth — what the footing minimum does to your foundation bid
- The builder table — the corridor firms who run these files routinely
Common questions
Do I need a building permit to build a house in Fremont County?
Yes. The county's Building Permit Application covers every structure except manufactured homes, which run on a separate form. The county also publishes a threshold sheet called “Do I Need A Building Permit?” for the cases people assume are exempt, such as shops, barns and additions.
Where is the Fremont County building department?
At the Fremont County Courthouse, 151 W 1st North, St. Anthony, ID 83445, reachable on (208) 624-7200. It is the same department whether your lot is in Ashton, Chester, Drummond or out on corridor acreage.
Which building codes does the county enforce?
Fremont County has adopted the 2018 International Residential Code, the 2018 International Building Code and the 2018 International Energy Conservation Code. The energy code is the one that most often surprises owners, because it governs insulation and window performance rather than structure.
What is the Permission Letter to Build?
A county form that was revised in 2026 — the county's own PDF was modified on 22 May 2026 — and the newest document in the set. It is the one most applicants have never seen, so it is worth asking the building department directly whether your file needs it.
Does the county permit cover septic?
No. Subsurface sewage disposal is permitted through Eastern Idaho Public Health, on a separate file with its own timeline. A building file for a house on unserviced land does not complete until that side is resolved.
Where does the snow load enter the permit file?
Through the structural design. Your lot's district sets the ground snow load the roof is engineered against, so it has to be settled before plans are drawn rather than corrected afterwards — and the county's district figure is not the only number in play.
Who pulls the permit, me or my builder?
Either can, and it is worth settling in the bid rather than assuming. A builder who pulls it carries the process; an owner who pulls it carries the responsibility for inspections and corrections. Ask the question before signing, not after.
Why do links to county documents keep changing?
The county renumbers its DocumentCenter files periodically, and the building permit application has already moved once. Every county link on this site was fetched and confirmed live on 13 August 2026, and they are maintained in one table so a break is fixed in a single place.