Published
The 200 square foot rule: what you can build on a cabin lot without a permit
The county publishes the answer, on a sheet with five question marks in the title
"Do I need a building permit for a shed?" is the most-asked small question on a cabin lot, and Fremont County answers it in a document literally headed Do I need a Building Permit????? It is a short list of work exempt from permit, it is free, and almost nobody reads it before building.
The headline is the one everybody half-remembers:
One-story/ground level detached accessory structures that are: Used as tool and storage sheds, playhouses and similar uses, provided the floor area does not exceed 200 square feet (18.58 m2). Covered porches are considered part of the square footage.
— Fremont County, Do I need a Building Permit????? (fremontcountyid.gov DocumentCenter, retrieved 2026-08-17)
Two hundred square feet is a 10 by 20 shed, or a 14 by 14. That is a generous exemption — and the sentence after it is the one that catches people.
Covered porches count
A covered porch is part of the square footage. That single clause redraws a lot of cabin-lot plans, because the small building people actually want is almost never a plain box. It is a 12 by 16 shed with a covered porch along the front to keep the snow off the door — and 12 by 16 is 192 square feet, comfortably under, until a 4-foot porch adds 48 and puts the whole thing at 240.
The county does not say the porch has to be enclosed, walled or usable. Covered is the test. On ground with this much snow load, a roof over the entry is the most natural thing in the world to add, and it is the thing that pushes an exempt structure into a permitted one.
Three conditions, all of which must hold
Being under 200 square feet is necessary and not sufficient. The county attaches three conditions to the same exemption:
| Condition | What it rules out on a cabin lot |
|---|---|
| Must be more than 3 feet away from any other structure | A shed tucked against the cabin, or a woodshed built onto the deck, is not exempt — and neither is one squeezed against a neighbouring outbuilding |
| Not used for habitation | The bunkhouse idea. A 200 square foot sleeping cabin for overflow guests is not covered by this exemption, however small it is |
| Does not have plumbing or electricity | A powered workshop, a lit shed, a pump house, or anything with a tap. Running a circuit out to an exempt shed removes the exemption |
The pump house is the case worth flagging. It is small, it is detached, and it is well under 200 square feet — and it exists precisely to house plumbing and usually electricity. It is exactly the structure that people assume is exempt and that the conditions exclude.
The rest of the list
The same sheet exempts nine other categories, and several of them come up on a cabin lot:
- Fences not over 6 feet high.
- Retaining walls not over 4 feet, measured from the bottom of the footing to the top of the wall — unless the wall is supporting a surcharge. Measuring from the footing rather than from ground level is the part that surprises people, because it makes a wall that looks 3 feet tall into a 4-foot wall.
- Water tanks supported directly on grade, up to 5,000 gallons, provided the ratio of height to diameter or width does not exceed 2 to 1.
- Sidewalks and driveways.
- Finish work — painting, papering, tiling, siding, carpeting, cabinets, counter tops and similar.
- Prefabricated swimming pools less than 24 inches deep.
- Swings and other playground equipment.
- Window awnings supported by an exterior wall, projecting no more than 54 inches from the wall and requiring no additional support.
- Reroofing, up to 2 layers total.
And then the sentence the county prints at the bottom of the sheet, which governs all of it: all structural modifications require a building permit to be applied for and approved.
What an exemption is not
This is the part that costs money, so it is worth being blunt about. Exempt from a building permit is not exempt from everything else. The permit is one requirement among several, and the sheet only speaks to that one.
- Setbacks still apply. An exempt shed still has to sit where the county's setbacks allow. The before-you-build page covers the permit path and where those come from.
- Private covenants still apply, and on subdivided ground here they are frequently stricter than the county about outbuildings, siding and roof pitch. A plat or an architectural committee does not care that the county exempted your shed.
- Snow load is a matter of physics, not paperwork. Nothing about an exemption makes a light shed survive an Island Park winter — the Island Park area page covers what the load here does to a roof, and a collapsed outbuilding is a real and common outcome.
- Utilities have their own rules. The moment you run power or water, you are outside the exemption anyway — and into wiring permits and inspections.
- Structural modification is always permitted work, by the sheet's own closing line, whatever the exemption list says about the original structure.
How to use the exemption sensibly
The exemption exists for genuinely small, simple, unserviced buildings, and it works well for exactly that. The practical route is to decide honestly which one you are building:
- A tool or storage shed, detached, unpowered, no porch or a porch counted in the total — the exemption fits, and it fits comfortably.
- A bunkhouse, studio, guest space or powered workshop — the exemption does not apply at any size, so design it properly and permit it. That is the cheaper mistake to avoid rather than to discover.
- Anything near the 200 square foot line — measure with the covered porch included, then leave margin, because a floor area recalculated by an inspector is not a negotiation.
Re-verify before relying on this. Every figure here was read from the county's own exemption sheet on 2026-08-17. County documents are revised without announcement, and the Fremont County building department at (208) 624-7200 is the authority on how the list is applied to a particular structure.
Common questions
Do I need a building permit for a shed in Fremont County?
Not if it is a one-storey, ground-level detached accessory structure used as a tool or storage shed, playhouse or similar use, with a floor area not exceeding 200 square feet — and it meets three further conditions on separation, habitation and services.
Does a covered porch count toward the 200 square feet?
Yes. The county's sheet says covered porches are considered part of the square footage. A 12 by 16 shed is 192 square feet, but a 4-foot covered porch across the front adds 48 and takes the structure to 240.
How far from the cabin does an exempt shed have to be?
More than three feet away from any other structure. A shed built against the cabin, the deck or another outbuilding falls outside the exemption regardless of its size.
Can I sleep in a 200 square foot cabin without a permit?
No. The exemption expressly excludes structures used for habitation. A small bunkhouse or guest cabin is permitted work no matter how little floor area it has.
Is a pump house exempt?
Generally not. The exemption requires that the structure does not have plumbing or electricity, and a pump house exists to contain both. Its small size does not rescue it.
What about running power out to a shed later?
Adding electricity takes the structure outside the terms of the exemption, which is written as a condition of the exemption rather than a one-time test at build. Treat it as a change that needs checking with the county.
How is a retaining wall measured?
The exemption covers retaining walls not over four feet in height measured from the bottom of the footing to the top of the wall, unless the wall supports a surcharge. Measuring from the footing rather than from grade catches walls that look shorter than they are.
Are driveways and sidewalks exempt?
Yes, both are on the county's exempt list. That is about the building permit only; an access onto a public road is a separate driveway or approach permit.
Can I reroof without a permit?
The list exempts reroofing up to two layers total. Beyond that, and for any structural modification, the sheet's closing line applies: all structural modifications require a building permit to be applied for and approved.
Does an exemption mean setbacks and covenants do not apply?
No. It exempts the structure from the building permit only. County setbacks still apply, and private covenants on subdivided ground are frequently stricter than the county about outbuildings.