Published
Can you live on the lot while you build?
Yes — there is a permit for exactly that
You can live on your lot while the cabin is being built, if the county issues a Temporary Use Permit for the temporary dwelling. Section 3.40 of the Fremont County Development Code is a short chapter with one big idea: some uses are allowed to exist for a while and then end, and the county issues them permits with clocks attached. The rule that matters to a build is 3.40.010, and it is worth reading whole because its limit is folded into its second sentence:
“A temporary dwelling may be permitted on the same lot as a permanent dwelling or use when the owner of the property is constructing or reconstructing a Permanent dwelling on the property. This use shall be limited to a maximum time period of two years provided that the building permit for the permanent dwelling remains active.”
— Fremont County Development Code, 2011 Edition (Ordinance 2011-04), section 3.40.010. Retrieved 17 October 2026
Unpack the conditions and the permit’s shape appears:
- Same lot — your temporary home sits beside the build, not down the road.
- Constructing or reconstructing a permanent dwelling — the cabin must be a real, permitted project; the application has to be in the county’s hands first.
- Two years maximum — the outer wall of the clock.
- While the building permit remains active — the clock does not run on its own; it runs only while the underlying build permit is alive, which makes the permit-validity page required reading before you plan a season in a trailer.
The five clocks, side by side
Section 3.40 issues temporary permits for more than construction housing, and the neighboring clocks explain how the county thinks: the closer a use sits to ordinary life, the shorter its leash. Every row below is the code’s own duration, from the section’s running text:
| Temporary use (section) | What it covers | Maximum duration |
|---|---|---|
| Temporary housing during construction (3.40.010) | A temporary dwelling on the same lot while you build or rebuild the permanent one | Two years, only while the building permit stays active |
| Temporary events (3.40.020) | Special events of a limited duration | Thirty (30) days |
| Temporary seasonal sales, non-farm (3.40.030) | Seasonal sales uses outside agriculture | Ninety (90) days |
| Public works and public facilities (3.40.040) | Uses tied to roads, bridges, and other public projects | Six (6) months |
| Commission-determined other uses (3.40.050) | Anything the Commission admits as temporary case by case | Ninety (90) days |
And one ceiling over all of them, from 3.40.060: if you need longer than your category allows, the application goes to the Commission (the county’s Planning and Zoning Commission — its hearing board) for review — but “In no case, shall a temporary permit be approved for a duration longer than two (2) years.” Two years is not a starting point to negotiate up from. It is the wall.
Conditions come with the territory
The chapter’s opening paragraph hands the county a conditioning power it uses freely:
“the Administrator may attach such conditions to the approval as he/she determines will reasonably mitigate any impacts of the proposed use.”
— Fremont County Development Code, 2011 Edition (Ordinance 2011-04), section 3.40. Retrieved 17 October 2026
The Administrator is the county’s planning staff officer — the same desk that reviews Class I applications administratively. Read the sentence as a promise in both directions: your temporary dwelling permit can carry conditions (where the trailer sits, what happens at the end, how the site is kept), and those conditions are enforceable parts of the approval, not suggestions. A build season goes smoother when the conditions are read on day one and calendared like inspections — the build timeline is the right place for that calendar.
The septic side is a second, separate track
Living in a trailer on the lot is not only a zoning question — the county pairs the temporary dwelling with a temporary-certificate path that has its own clock and its own septic-first conditions, and the septic site has written that path up with the figures. The short version: expect two approvals, not one, and expect the septic one to be the longer lead item. When the cabin itself is finished, the end of temporary living runs into the county’s final gate — the certificate of occupancy page covers what that last document does and does not promise.
Planning a build-season on the lot: five moves
- Get the building permit application filed and active first — the Temporary Use Permit’s two-year clock only runs while that permit lives.
- Request the 3.40.010 temporary dwelling permit at the county desk, Planning & Building, (208) 624-4643, 125 North Bridge St., St. Anthony.
- Start the septic-side paperwork in parallel — it is the long-lead item on the trailer path.
- Read every attached condition the day the permit issues, and put each one on the same calendar as your build milestones.
- Plan the exit before the entry: where the temporary dwelling goes when the two years end, and how the lot reads at the final inspection.
The county’s answer to a build-season residence is yes, on a clock, with conditions. The two-year cap sounds generous until a winter eats one of them — treat the Temporary Use Permit as a season ticket, not a lease, and the arithmetic stays honest.
Common questions
Can I live in an RV or trailer on my Island Park lot while building?
Yes, with a Temporary Use Permit under section 3.40.010 — a temporary dwelling is allowed on the same lot while the owner constructs or reconstructs the permanent dwelling, for up to two years while the building permit remains active. The trailer also needs the septic-side temporary certificate, which is a separate track.
How long can the temporary dwelling stay on the lot?
Two years maximum under 3.40.010, and only while the building permit for the permanent dwelling remains active. Section 3.40.060 adds the absolute ceiling: in no case may a temporary permit be approved for a duration longer than two years.
What if the build takes longer than two years?
The code provides no extension beyond the ceiling — 'in no case' longer than two years. Longer durations go to the Commission for review under 3.40.060, but the two-year wall stands; beyond it, the situation is a new question for the county desk, not an automatic renewal.
Do the 30-day and 90-day limits apply to my construction trailer?
No. Those clocks belong to other categories — temporary events (30 days), non-farm seasonal sales (90 days), and Commission-determined uses (90 days). Construction housing has its own two-year rule under 3.40.010.
Can the county attach conditions to the temporary dwelling permit?
Yes. Section 3.40's lead gives the Administrator authority to attach conditions that 'reasonably mitigate any impacts of the proposed use.' Conditions are enforceable parts of the approval — read them the day the permit issues.
Does the Temporary Use Permit replace septic or health requirements?
No — the zoning permit and the septic-side temporary certificate are separate approvals with separate conditions. The septic site's page on living in an RV while you build carries that path's figures and requirements.