1-Story Barndominium in Tennessee

Per square foot, usually not, and the reason is worth understanding before you decide. Roof and foundation both scale with footprint rather than with finished area, and a single storey needs roughly twice the footprint for the same square footage. In NAHB's 2024 national cost-of-construction survey, foundation work accounted for 10.0% of total construction cost and framing and roof for 11.6% — about 21.6% between them, all of it footprint-driven. Split across two floors, that share per square foot falls. What comes back the other way is real too: no stair taking floor area out of both levels, no second-floor structural system, no taller wall assemblies or scaffolding, and one mechanical run instead of two. There is a local dimension as well, because the rules that key off footprint all land on the single-storey plan first — lot coverage caps, graded pad area, and Chattanooga's requirement of two exit doors on any dwelling with a footprint over 700 square feet. We do not publish a percentage for the net, because no barndominium-specific study segmented by storey count exists and the figures circulating online have no primary source behind them.

Almost certainly not, and this is the most useful thing we can tell someone drawing a modest single-level plan here. Of the twenty jurisdictions researched for this site, only one sets a minimum: the City of Cleveland, whose zoning ordinance requires a single-family dwelling to have not less than 500 square feet of living space on a permanent foundation. Maury, Jefferson, Robertson, Williamson, Rutherford, Wilson, Sumner, Bradley, Loudon, Sevier, Blount, Washington and Knox counties impose none; nor do Murfreesboro, Nashville, Memphis and Shelby County, Chattanooga and Hamilton County, Clarksville and Montgomery County, or Cookeville. Putnam County has no county zoning in the unincorporated area at all. Three square-footage figures in these ordinances get misreported as minimum house sizes and are not: Robertson County's 600 sq ft and Loudon County's 600 sq ft are both in the definition of a prefabricated dwelling and exist only to separate it from a mobile home, and Montgomery County's 480 sq ft sits in the mobile-home table and does not reach its agricultural or residential districts. The binding constraint on a small plan in these counties is the minimum lot, not the minimum house.

In two of our jurisdictions, yes, and in both cases it is a city rule with a defined scope rather than a county-wide one. The City of Knoxville's zoning code, section 4.4.A.4, requires a primary structure in the EN district to meet two of three requirements: a roof that is flat under a 1/12 pitch in one plane, or steep at 6/12 or more, or articulated; more than one finished floor level; or a shape with at least eight sides, counting wall segments of four feet or more. A single-storey rectangle with a 4/12 gable meets none of the three. It applies in that district and in that city only — Knox County's A zone has nothing comparable. The City of Chattanooga's section 38-42(m) requires windows, entrances, porches or other architectural features on all street-facing facades to avoid the appearance of blank walls, which is one sentence and applies to site-built detached dwellings inside the city; Hamilton County has no equivalent. Private covenants can be far stricter than either. Tellico Village in Loudon County requires a minimum 4/12 pitch with at least six prominent roof planes, prohibits standing-seam and corrugated metal roofing, and permits wall materials from a closed list that does not include metal panel — while the Loudon County zoning resolution itself sets no pitch, material or floor-area rule at all.

It is the configuration that reaches one first, since the whole building sits on the ground. The caps in our jurisdictions range widely and the district matters more than the county. Robertson County caps building coverage at 10% in AG-1, rising to 25% in AG-2 and 30% in RP-80; Maury County is 10% in its 15-acre agricultural district and 30% in its rural residential ones; Sumner County is 20% in AR, RP and RR and 25% in SR; Rutherford County is 20% for residential use in AR and RL and 25% in RM; the City of Knoxville's EN district is 25% building coverage with a separate 35% impervious cap; Knox County's A zone is 30% for main and accessory buildings combined; Wilson County's A-1 is 35%, with accessory structures separately limited to 20% of any rear yard; Murfreesboro's RS-15 is 35%; Cookeville's RS-20 and RS-15 are 40% including accessory buildings. The 10% figures read worse than they behave, because they sit on districts with fifteen-acre minimum lots. The ones that genuinely shape a wide building are the suburban caps on small lots — Murfreesboro's largest single-family district is 15,000 square feet, about a third of an acre. Sevier County adds a different constraint in its hillside and steep-slope overlays, where post-construction impervious area may not exceed 15% of the lot.

No. IRC R301.1.1 allows a house to be built to the prescriptive provisions of one of three standards — the AWC Wood Frame Construction Manual, AISI S230 for cold-formed steel, or ICC 400 for log structures. A clear-span rigid frame or post-frame building matches none of them, so R301.1.3 applies and those elements are designed in accordance with accepted engineering practice. That is true on one level and on two, and it reaches the floor as well as the roof, because prescriptive floor-joist span tables stop around 23 to 25 feet. Three Tennessee jurisdictions say much the same thing in their own documents. Rutherford County's residential plans-review list names pole barn type structures with living space regardless of square footage and requires drawings sealed by a Tennessee registered architect or engineer. Washington County answers in its own FAQ that barndominiums are allowed anywhere single-family dwellings are, with stamped drawings from a design professional required for all alternative construction methods. Cumberland County's requirements sheet calls for a letter from an engineer for any wall above 10 feet tall and for footings or slabs on backfill. None of the three carves out an exception for a single storey. What one level buys you is a simpler thing to engineer, not a way around it.

It can, and two of our cities have written local amendments that land squarely on a long single-level plan. The City of Chattanooga replaced R311.2 so that dwellings with a footprint of more than 700 square feet must have at least two exit doors, each giving direct access from the habitable portions of the dwelling to the exterior without travelling through a garage; the model code requires one. Every barndominium exceeds 700 square feet of footprint, and on one storey the footprint is the whole house, so this applies to every plan in the city. The City of Murfreesboro added a section requiring that bedrooms not be the only means of access to other bedrooms or habitable spaces, and not serve as the only means of egress from other habitable spaces — directly relevant to the pass-through layouts common in stock barndominium plans, where rooms are strung along a single clear span. Both cities are on the 2018 edition of the residential code, which is where those section numbers belong. One more worth knowing on a shop-forward plan: Cumberland County states plainly in its own guidance that garage doors do not count as a means of escape, so a shop bay is not an egress route for the rooms behind it.

Often not, and this is where we would rather talk you out of it. A single storey needs the widest flat pad of any configuration, so on sloping ground it buys the most cut and fill, and the depth of cut at the uphill edge grows with the width of the building as well as its area. In Tennessee the cut is the problem: shallow limestone, solution cavities and sinkholes across the Valley and Ridge, and rock a foot down in places on the Cumberland Plateau, with depth to rock that can vary across a single footprint. Cumberland County's own sheet requires a slab to sit on undisturbed soil or on engineered backfill, calls for an engineer's letter for footings or slabs on backfill, and checks slope at the footing inspection at no more than 1 in 10. Septic is the other half of it and it is a state programme under TDEC rules rather than a county health department. Trench bottoms need four feet above rock, slope limits of 30% and 50% apply, and acceptable percolation is a band of 10 through 75 minutes per inch, so soil can fail for draining too fast as well as too slowly. TDEC's own soil tables flag the Crossville and Ramsey series as generally too shallow to bedrock for a septic system, and Crossville is the Cumberland County seat. Meanwhile the same slope costing you money is the condition a walkout basement wants. On genuinely flat ground the single-storey argument is strong; on a slope it is worth pricing against a walkout, and worth getting the soil evaluation done before the land is bought.