Engineering & sign-off
Who has to stamp your plans in St. Anthony
Published · every figure below was checked against its primary source on the date shown.
Three triggers, and they are independent
“Do I need an engineer?” sounds like one question. Around St. Anthony it is three, coming from two different desks, and it is entirely possible to fall under one and not the others.
| Trigger | Whose rule | What it demands | When it applies |
|---|---|---|---|
| Registered design professional | City | Submittal documents prepared, or signed off on, by one | Inside city limits, on the residential application |
| Snow-load threshold | County | Designed by an Idaho-licensed structural engineer or architect | Structures “within a 70lb/ft² roof snow load” |
| Post and beam | County | Engineered stamped plans | All free-standing post & beam structures, unconditionally |
The city's rule: about who, not about what
“The submittal documents must be prepared (or signed off on) by a registered design professional.”
— City of St. Anthony, Residential Building Permit Application, Rev. 11.2023, retrieved 14 August 2026
Notice what this rule is indexed to. Not square footage, not snow load, not the type of structure. It is a requirement about who prepares the documents, attached to the residential application itself.
The application does not define “registered design professional” on the form, and this site will not invent a definition the city has not published. That is a question with a definite answer available from City of St. Anthony, 420 N Bridge Street Suite A, St. Anthony, ID 83445 — (208) 624-3494; inspections (208) 709-3030, 24 hours' notice, and it is worth asking before you commission drawings rather than after a submittal comes back.
The parenthetical matters too. “Prepared (or signed off on)” contemplates a professional reviewing and signing someone else's work. In practice, plenty of professionals will not sign off on drawings they did not produce, or will only do so after changes substantial enough that they may as well have drawn them. Treat the sign-off route as something to arrange in advance, not as a fallback.
What each trigger costs you if it applies
- The city's design-professional rule shapes who you commission at the very start, because it governs the submittal itself rather than one calculation inside it.
- The county's snow-load rule adds a structural engineer or architect to a project that might otherwise not have needed one.
- The post and beam rule adds a full stamped engineering package, and it is the one most often discovered late because nothing about a modest shop suggests it.
The county's snow-load rule, and its ambiguity
The county's checklist requires structures built “within a 70lb/ft² roof snow load” to be designed by a structural engineer or an architect licensed in Idaho, with plans on a minimum of 11×17 paper.
The wording is imperfect. It does not say “70 or more.” But the county's own snow-load districts are set at various figures with none at exactly 70, so the only reading under which the sentence does any work is as a threshold. On that reading, the St. Anthony District at 50 PSF sits below it.
Which would be good news, and is exactly why it should not be assumed. If your project turns on not needing a stamp, get the county to say so: Fremont County Building Department, Fremont County Courthouse, 151 W 1st North, St. Anthony, ID 83445 — (208) 624-7200. One call, and it is either a saved cost or a caught problem.
The rule with no conditions at all
“***ALL FREE-STANDING POST & BEAM STRUCTURES REQUIRE ENGINEERED STAMPED PLANS.***”
— Fremont County, Pre-Construction Check List for Building Permits, rev. 17 April 2026, printed in the application block. Retrieved 14 August 2026
This one is different in kind from the other two. There is no threshold to fall below and no professional-qualification question to resolve. If the structure is free-standing post and beam, the county wants engineered stamped plans, and the low snow load in this district does not change it.
Since a large share of shops, barns and post-frame homes on this valley floor are exactly that, this is the trigger most likely to apply and the least likely to be anticipated. It belongs in the budget from the first conversation.
Worked examples
| Project | City design professional? | County snow-load rule? | Post & beam rule? |
|---|---|---|---|
| Stick-framed house on a city lot | Yes — city submittal rule | n/a — city issues the permit | No |
| Stick-framed house on county ground, 50 PSF district | No | Ask — 50 appears to fall below the stated threshold | No |
| Post-frame barndominium on county ground | No | Ask, but it is moot | Yes — unconditionally |
| Detached post-frame shop on county ground | No | Ask, but it is moot | Yes — unconditionally |
The pattern is worth naming. For post and beam, the other two questions stop mattering — you need stamped plans either way, so the only remaining question is who produces them.
Three calls, in this order
- Which desk? Establish whether the parcel is inside the St. Anthony city limits. Everything else depends on it.
- If city: ask who the city accepts as a registered design professional for a project like yours, and whether sign-off on third-party drawings is acceptable to them.
- If county: ask two questions in one call — does the 70 lb/ft² sentence mean my 50 PSF district build needs a stamp, and is what I am proposing free-standing post and beam in your view?
None of those calls costs anything, and all three are cheaper than a submittal that comes back. If you would rather have someone frame the questions for you first, ring (208) 656-1745.
Related reading on this site
- The St. Anthony District snow load is 50 PSF — where the 70 lb/ft2 threshold sits relative to this district
- Building a barndominium in St. Anthony — the post and beam rule in the context it bites hardest
- The city and the county cite different building codes — the other place the two desks diverge on paperwork
Common questions
Do I need an engineer or an architect to build a house in St. Anthony?
It depends on which side of the city limits you are on and what you are building. There are three separate triggers across the two desks, and they are worth knowing individually because you can be caught by one and not the others.
What does the city require?
The city's residential building permit application states that the submittal documents must be prepared, or signed off on, by a registered design professional. That is a requirement about who prepares the documents rather than about the size or type of the building.
What does the county require based on snow load?
The county's checklist says structures built “within a 70lb/ft² roof snow load” are required to be designed by a structural engineer or an architect licensed in Idaho. The natural reading is a threshold at 70. The St. Anthony District is set at 50 PSF, which on that reading falls below it — but the sentence does not say “or more,” so confirm with the county.
What is the trigger that applies no matter what?
Free-standing post and beam structures. The county's checklist requires engineered stamped plans for those, printed in capitals, with no snow-load condition, no size threshold and no exemption attached.
What is a registered design professional?
The city's application does not define it on the form, and this site is not going to supply a definition the city has not given. Ask the city office who it will accept for your project — that is a two-minute question with a definite answer, and guessing at it is how a submittal gets rejected.
Does a stamp cost a lot?
It is a real line item and worth pricing early rather than discovering late. What makes it expensive is not the fee itself but the timing: an engineering package needed at submittal, and commissioned at submittal, delays everything behind it.
Can my builder's plans be signed off by an engineer rather than drawn by one?
The city's wording is “prepared (or signed off on) by a registered design professional,” which contemplates both. Whether a specific professional will sign off on someone else's drawings is between you and them — many will not, or will only after substantial revision. Do not assume it is a formality.
What should I do first?
Establish which side of the line the lot is on, then ask that office directly which of these applies to your specific project. All three questions can be answered in one call each, before you have spent anything.
Ask about a build in St. Anthony
Describe the parcel and roughly what you have in mind. What comes back is an honest read on which firms here take that kind of work, plus the one thing most people have not established yet: whether the city or the county will be reviewing your plans. Free, and nothing automated ever follows.
- Say where the ground is and what you intend to put on it.
- You are pointed toward the firms in this town with that work behind them.
- From there it is between you and them. No commission, no introduction fee, and nobody standing between you and your own contract.
One contact method is plenty — whichever you prefer. A human being writes back.