The building code half is the short half
Virginia keeps two exemption lists and a patio appears on neither. Section 102.3 lifts certain work out of the code, Section 108.2 lifts other work out of the permit application, and a patio slab is absent from both. What ordinary patio work rides on instead is the building official's discretion for work that is minor and ordinary and does not adversely affect public health or general safety, and that is the same mechanism a driveway rides on. We are not going to work it twice here. It is set out on the Virginia permits page, and the number to call is your county building department, or the town's where a town such as Hillsville issues its own permits.
The reason this half is short is that it ends at one desk. Somebody at the counter makes that read about your job, and it is theirs to make rather than ours. The half nobody warns you about is the one underneath.
The second question is a zoning question, and it is a different office
Setbacks, yards and where a thing may sit do not come from the building code at all. They come from a local zoning ordinance, which a county or a town may adopt and does not have to, carrying whatever distances that locality wrote into it. Why that leaves no statewide number, and some addresses around here with no zoning number at all, is the argument of how close to the property line concrete can go. This page picks up at the question that comes before any distance.
So the building department and the zoning office are two separate phone calls, and they answer to different rulebooks. The building official reads the building code. The zoning administrator reads the ordinance, and for a patio the part of that ordinance to read first is not the table of distances. It is the page of definitions.
When a patio stops being flatwork and starts being a structure
This is the whole page. Nearly every zoning ordinance read for these pages writes its setback against a "structure" or a "building," which means whether that rule reaches your patio is decided by how your ordinance defined one word. The ordinances around here do not agree with each other. That disagreement is the honest answer, and it is the part a statewide guide cannot give you.
Surry County, North Carolina settled it by writing an exclusion list into the definition itself. Its ordinance says a structure "does not include landscape features, such as" a list that names at-grade slab patios and driveways among other things, and its setback is measured to a structure. Do not widen that past setbacks, because the same ordinance still carries separate driveway standards of its own. Giles County, Virginia drafted the opposite way. The copy of its zoning ordinance posted online, captioned 1992 as amended and put up in 2019, defines a structure as "Anything constructed or erected, the use of which requires a location on the ground," with no exclusion list at all, and whether that is still the wording in force is a question for the county rather than for the PDF. A poured slab is constructed, and it requires a location on the ground. Giles then writes its yard rule against buildings, describing a yard as space "open, unoccupied, and unobstructed by buildings from ground to sky" except where encroachments and accessory buildings are expressly permitted, and a slab at grade leaves that space open to the sky. That makes Giles a genuinely arguable case, and the zoning administrator is the person who settles it, not us.
Pulaski County, Virginia shows two definitions in one ordinance pulling different ways. Its definitions article calls a structure anything constructed or erected with a fixed location on the ground, then measures a setback to the vertical wall, and a flat slab has no vertical wall to measure to. The same article says retaining walls other than seawalls, and fences, are not deemed structures unless the ordinance provides otherwise, and it gives driveway a definition of its own. Inside the Town of Hillsville, where our shop is, a structure is anything constructed or erected whose use requires a permanent location on the ground, while the setback line is drawn against the principal building. Four ordinances, four different ways of getting at one homeowner's patio. Copies posted online do go stale, so confirm the current wording with the zoning office rather than with a PDF somebody scanned years ago.
Which side of a line you are on decides more than the county does
Out in Carroll County, the county our shop sits in, there is no county-wide zoning ordinance, so there is no county zoning definition of structure to read, which is part of why the Carroll County permit page reads the way it does. Cross into the Town of Hillsville, inside that same county, and the town's own definitions apply. Grayson County, right next door, runs it the other way round. The county's zoning ordinance covers the land outside its three incorporated towns, while Independence, Fries and Troutdale administer their own zoning, even though the county's Building Department issues the building permit inside all three. So for a patio in Independence, the question of where it may sit goes to the town and the question of how it is built goes to the county.
Read that with a patio in mind. The same slab can sit under no zoning definition at all on one side of a town line and under a definition of structure on the other, and the town line often decides more than the county line does. In North Carolina a town's zoning can also reach out past the town limits into an established extraterritorial jurisdiction, so a rural address is not automatically outside it. Asking a friend one town over is how people end up confident and wrong.
The call that settles it, in words a zoning office can answer
Keep the call short and build it around the definition. Ask whether the lot is zoned at all, and by the county or by a town. Ask which district it sits in. Then ask whether the ordinance's definition of structure reaches an at-grade slab patio, and whether its setback is measured to a structure, a building or the principal building, because the ordinances above use all three. Get the answer in writing if the office will give one, with the name of whoever gave it. Never treat a patio as automatically exempt from a setback, and never assume it is caught by one either. The ordinances read for these pages split, and the split is the answer.
No permit is not the same as no rules on the building side either. The section that excuses work from a permit application says in its own opening sentence that it is not excusing that work from the rest of the code. Nobody coming out to look at your patio does not make the base under it any better or the slab any thicker. That part does not depend on which county you are standing in, and it is the part we control. What goes under a patio is the same job in Hillsville, Independence or Mount Airy.