What the Virginia exemption actually says
The exemption is statutory before it is anything else. Code of Virginia section 36-99 B says that "farm buildings and structures shall be exempt from the provisions of the Building Code." The regulation carries it at Section 102.3 item 9 of the Uniform Statewide Building Code, and Section 102.3 is the list that exempts from the code entirely, not Section 108.2, the list that only excuses the permit application. That is a broader exemption than most people assume they are working with.
The definition sits at section 36-97, and the qualifier that matters is "not used for residential purposes." It is not "not used for human occupancy," which is the version that circulates and would give you the wrong answer twice. A farm office qualifies, because the definition names business or office uses relating to the farm operations. So does the equipment shed, because it names maintenance or storage of vehicles, machinery or equipment on the farm.
The limits are written into the same subsection. A building on a farm operated as a restaurant is carved out, on conditions section 36-99 B spells out and that are worth reading before anybody relies on them. Farm buildings lying in a flood plain or a mudslide prone area stay "subject to flood-proofing regulations or mudslide regulations, as applicable." And where the public is invited in for an agritourism activity as defined in section 3.2-6400 and the building is used for display, sampling or sale of farm products, section 36-99 B adds three things: portable fire extinguishers, a simple written plan for an emergency, and a posted sign no smaller than 24 inches by 36 inches stating that the building is exempt from the Uniform Statewide Building Code. Those two conditions travel together, and a barn rented out for events is not automatically inside them.
It reaches the slab, and it does not obviously reach a bare pad
The hook is in the definitions, not in a sentence about concrete. Section 36-97 defines a building and then says the word building is read as though followed by "or part or parts thereof." A floor slab and the footings under it are parts of the barn, the barn is exempt from the code, so the slab rides along. That is a reading of the text rather than something the statute prints, and it is worth saying plainly that the words slab, floor and footing appear nowhere in the exemption.
Two counties in our range publish a farm structure form we could open, and one of them spells the consequence out. Wythe County's form says the Building Code Office "requires no inspections or fees, and none will be performed or charged," and that a certificate of occupancy is not required and none will be issued. Carroll County publishes its own farm structure statement. Either way, the form gets signed before the building goes up, not after somebody asks about it.
A bare pour with no building over it is a genuinely different question, and no document we could open answers it. A feed pad, a bunker silo apron, a wash pad, an equipment parking pad: none of them is named, and Virginia's definition of a structure lists things like tanks, towers, piers, trestles and storage bins, which a flat pad is not obviously among. That one is a short call to the county building official, and it is not something we will guess at on your behalf. We build feed pads either way, and the call takes less time than staking one out.
Three things the exemption does not touch
Erosion and sediment control. Virginia's agricultural exclusions cover clearing for bona fide agricultural purposes, tilling, planting, harvesting, feedlot operations and a run of agricultural engineering operations such as terraces, check dams, ponds and ditches. Building a barn is not on that list, and Carroll County writes it out on its own bona fide agricultural claim form: "The construction of agricultural buildings is not included. Therefore, the agricultural exemption does not apply to the construction of farm buildings such as barns, stables, livestock houses, etc." The trigger under Code of Virginia section 62.1-44.15:34 is a land disturbance of 10,000 square feet or more, which is the figure that applies outside a Chesapeake Bay Preservation Area, and a locality is free to set its own threshold lower.
The entrance. If the drive to that barn ties into a road VDOT maintains, VDOT's private entrance permit covers, by name, an entrance that allows agricultural operations to obtain access to fields. Read that the right way round: the field entrance is a permit category, which is the opposite of an exemption. On the North Carolina side, the driveway statute, G.S. 136-93(a), carries no farm exception at all, and the words farm, agricultural and field do not appear in it. The entrance permit page has the mechanics.
The locate. Virginia's dig law lists eight exemptions and none of them covers a machine on a footing line. The two that come closest are hand digging by an owner or occupant of a property and the tilling of soil for agricultural purposes. North Carolina does have agricultural locate exemptions, which lift only the notice requirement, and for anything past tilling soil less than 12 inches deep they hold only where the work stays clear of every operator's right of way, easement and permitted use, which is exactly the thing a landowner cannot know without asking somebody. We place the ticket for the work we do, on both sides of the line, and we would rather wait on marks than find a line with a trencher.
Zoning is a separate desk, and the two states are not built alike
Virginia keeps the two apart on purpose. The definition of building regulations in section 36-97 says in terms that it "does not include zoning ordinances or other land use controls" that do not affect how a building is built. So a barn can sit outside the Building Code and inside a zoning ordinance at the same time. Virginia has no statewide bona fide farm zoning exemption. What it has is section 15.2-2288, which forbids requiring a special use permit for production agriculture in an agricultural district and then says, in the same section, that localities "may adopt setback requirements, minimum area requirements and other requirements."
County practice fills that gap unevenly, and the split is sharper than people expect between neighbors. Grayson County runs its own zoning agricultural exemption, with its own form and no fee. Carroll County has no general county zoning ordinance at all, while the Town of Hillsville inside it does. Two adjoining counties, two different answers, and neither of them is the state's answer.
North Carolina builds it the other way around. Its farm carve out starts in zoning, at G.S. 160D-903(a): "County zoning regulations may not affect property used for bona fide farm purposes." The building code exemption then borrows that test wholesale, defining a farm building as a nonresidential building or structure used for a bona fide farm purpose as provided in that zoning statute. So in North Carolina the zoning answer decides the building code answer, and in Virginia the two never touch.
In North Carolina it depends on where the building stands
The North Carolina building code exemption is geographic before it is anything else. G.S. 143-138(b4) says building rules do not apply to farm buildings located outside the building rules jurisdiction of any municipality. Inside one, only greenhouses and therapeutic equine facilities keep the exemption, alongside a primitive camp and a primitive farm building, which carry no geographic limit at all. On county land in Surry, Alleghany, Stokes and Wilkes, outside any municipality's building rules jurisdiction, that first clause is the one that answers it. Inside a municipality's building rules jurisdiction the geographic clause stops working, and a barn there has to qualify some other way, for example as a primitive farm building, which the statute defines broadly enough to reach sheds and barns used for traditional or heritage farming practice. Whether a particular building lands in that category is the county's reading and not ours, and the difference can be one field wide. Getting concrete back to any of these buildings is its own problem: here is how we handle farm roads.
Proving a bona fide farm is an open question, not a checklist. G.S. 160D-903(a1) says any of four documents is "sufficient evidence that the property is being used for bona fide farm purposes, but other evidence may also be considered": a farm sales tax exemption certificate, a property tax listing showing present use value eligibility, a Schedule F from the most recent federal return, or a forest management plan. Sufficient is not the same as required, and a county page that reads like a checklist is quoting less than the statute says.
One thing North Carolina says out loud surprises people. Even where the zoning exemption protects the farmhouse, subsection (a) of that zoning statute describes a residence on the farm as one "constructed to the applicable residential building code." The zoning exemption and the building code exemption are two separate things and the house gets one of them, not both. Both North Carolina sections were amended effective July 1, 2026, and the substantive change was a new category for buildings producing agricultural products derived from animal waste. The evidence test and the farmhouse sentence above are not the parts that moved. The date is still worth carrying, because a neighbor's account of how this worked a few years back is describing a statute that has been edited since.
The exemption follows the use, which means it can end
Both states define the exempt thing by what it is used for, in the present tense. Virginia says "not used for residential purposes" and "used primarily for" a listed set of farm uses. North Carolina says a nonresidential building or structure "that is used for a bona fide farm purpose." Neither one hands a structure a permanent status, and neither one is a grandfather clause. The day the pole barn becomes a dwelling it is not a farm building in either state.
What no document settles is the path back. Nothing we could open says what a county asks for when a farm building that was never permitted is converted to something else: whether footings get exposed, whether an engineer's letter is accepted, what it costs or how long it takes. Nobody should read a number or a procedure into that silence, us included. Talk to the building official before a yard of concrete is ordered. The word primarily is not defined either, so a pole barn storing hay on one end and a side business's equipment on the other is a conversation with the county, not a rule you can look up.