Wilson County 2018 IRC with Tennessee amendments

Barndominium Builders in Wilson County, TN

Wilson County is one of the fastest-growing counties in the Nashville ring and still 83% unincorporated, which is where the acreage is. The county runs its own Building Codes Department out of the Courthouse Annex in Lebanon and enforces the 2021 IRC, a newer edition than either Lebanon or Mt. Juliet, which permit land inside their own city limits under the 2018 IRC. In the A-1 Agricultural district a single-family dwelling is permitted by right on 80,000 square feet, and the ordinance sets no minimum floor area for the house at all.

Wilson County at a glance

County: Wilson County
Population: 175,033
ZIP codes: 37087, 37090, 37122, 37184, 37071, 37136
Site visits: About 45 miles east of our Franklin base, straight across on I-840 to Lebanon and Mt. Juliet

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Building conditions in Wilson County

What actually changes from one Tennessee jurisdiction to the next: who issues the permit, whether the residential code is enforced there at all, what the structure has to be engineered to, and what the ground is like. These are the numbers your drawings have to satisfy.

Build conditions for Wilson County, drawn from the sourced facts on this page. Every figure above is cited in the quick-facts panel below, with its source and vintage.

Who permits and inspects

The Wilson County Building Codes Department at 233 East Gay Street in Lebanon permits and inspects construction in the unincorporated county, and the State Fire Marshal's Office lists Wilson County as an exempt jurisdiction, which is the status a county holds when it enforces its own codes rather than the state residential programme. Lebanon and Mt. Juliet each hold their own exemption and permit land inside their city limits. Applications go through the MGO portal, and the office does not process permits after 3.30pm.

Tennessee State Fire Marshal's Office, Residential Jurisdictions and Inspectors, stamped accurate as of 21 August 2026, and Wilson County Building Codes Division, wilsoncountytn.gov, both fetched 31 Aug 2026

Codes enforced

Unincorporated Wilson County enforces the 2021 International Residential Code with adopted appendices, the 2018 IECC with state approved amendments, and the 2021 IBC, IPC, IMC, IFGC, IEBC and ISPSC. The City of Lebanon and the City of Mt. Juliet both build houses to the 2018 IRC. One county therefore carries two residential code editions, and the unincorporated area is on the newer of the two.

Wilson County Building Codes Division adopted codes list, City of Lebanon Building Inspection Guidelines, and City of Mt. Juliet Building and Codes Department adopted codes, all fetched 31 Aug 2026

Design wind speed and frost depth

Confirmed with the county per parcel. Tennessee leaves Table R301.2 for each jurisdiction to fill in, and Wilson County publishes no filled-in version, so no ultimate design wind speed, ground snow load, seismic design category or frost line depth appears in its codes documents or in its zoning ordinance. We ask the Chief Building Official for the figures before anything is engineered.

Wilson County Building Codes Division documents and the Wilson County Zoning Ordinance, last revision 21 July 2026, searched in full, fetched 31 Aug 2026

Zoning district and minimum lot

A-1 Agricultural takes a single-family dwelling by right on a minimum lot area of 80,000 square feet, which applies whether or not the lot has public sewer, with a rider that the state environment department may require more. Lot width is 125 ft without sewer and 100 ft with. Setbacks run 60 ft from an arterial, 40 ft from a collector and 30 ft from a minor street, 20 ft at the side and 40 ft at the rear, with buildings covering no more than 35% of the lot. R-1 Rural Residential runs the same pattern on 40,000 square feet.

Wilson County Zoning Ordinance Sections 5.20.02, 5.20.05 and 5.10.05, last revision 21 July 2026, fetched 31 Aug 2026

The foundation skirt rule

Every principal single-family dwelling with a finished floor above the surrounding grade has to carry a brick, stone, masonry or stucco panel curtain wall around the whole perimeter, running from just below the finished floor down to ground level and left un-pierced except for ventilation, utility connections and access. This is the standard a post-frame or pier-set building with plain skirting fails. A slab whose finished floor is not above the surrounding grade does not trigger it.

Wilson County Zoning Ordinance Section 3.12.04, Foundation Requirements for Residential Structures, Resolution 05-7-2, last revision 21 July 2026, fetched 31 Aug 2026

Permit fee and Adequate Facilities Tax

The residential building permit is $0.70 per square foot and the Adequate Facilities Tax is a flat $5,000 on every new dwelling, paid on a separate cheque, both collected in full when the application is made. The square footage the fee is calculated on includes the attached garage, sunrooms, bonus rooms and the basement, finished or not, so an attached shop bay sits inside the fee base. A stormwater permit for a new home is a further $350.

Wilson County Residential Building Permit Fee Schedule, the Home, Addition and SDU Building Permit Application Checklist 2026, and the Building Inspector and Codes FAQ, wilsoncountytn.gov, fetched 31 Aug 2026

Also worth knowing before you build in Wilson County

No minimum house size: Wilson County sets no minimum heated floor area for a house in A-1 or R-1. The only dwelling square-footage limits in the ordinance run the other way and apply to secondary units: a detached accessory dwelling unit is capped at 1,000 square feet of total heated area and internal accessory quarters at 600, one of each per property, both on a permanent foundation meeting Section 3.12.04.
Metal cladding on a house: Wilson County's restriction on metal siding sits in Section 3.55, headed Site Development and Landscaping Standards, Commercial and Industrial Zone Districts. Its two subsections apply within commercial zone districts and within industrial zone districts respectively. Neither reaches A-1, A-2 or R-1, and neither reaches a dwelling, so there is no metal-cladding restriction on a house in the unincorporated county.
Detached shops: height and matching: An accessory building on accessory setbacks is capped at 22 ft in height. On principal setbacks it can go to 30 ft. On accessory setbacks it may still reach 30 ft, but only if it matches the predominant two roof pitch angles and the building material of the house. Accessory buildings also have to stand at least 8 ft wall to wall from any other structure and cannot cover more than 20% of the rear yard.
Post-frame is a recognised foundation here: The county's own inspection document defines the foundation inspection as covering, among other things, footings, monolithic slabs and post holes. Footings take a minimum of two runs of #4 rebar with 3 inches of cover at the bottom and in the corner, anchor bolts start between 3.5 and 12 inches from a corner and repeat at 6 ft centres, and any block or basement wall over 10 ft has to be engineered with documentation.
Septic and electrical are not the county: The county states plainly that its codes and zoning department does not permit or conduct electrical, septic, step or stormwater inspections. Septic is the Tennessee Department of Environment and Conservation field office on 931-520-6688. Electrical is the State of Tennessee Electrical Office for Wilson County, based in the City of Lebanon Public Works building at 410 Park Drive, and a passed state electrical rough-in has to be on file before the county will do the framing inspection.
Two deadlines worth knowing: A residential building permit cannot run longer than 24 months without a certificate of occupancy, and going past that needs relief from the Board of Zoning Appeals. Inspectors have 72 business hours to attend once an inspection is requested. A failed setback inspection costs $75, and re-inspections run $75, then $150, then $300 with a stop-work order.
Five acres changes the paperwork: A surveyed plot plan is not required for a tract above 5 acres, and the setback inspection is only triggered where the lot is under 5 acres and no stamped surveyed plot plan came in with the application. A detailed plot plan is still required on every permit whatever the tract size, and inspections are failed where the plot plan and the site do not agree.
A barn is exempt from the height limit until someone lives in it: The zoning ordinance exempts agricultural buildings, including a barn and a silo, from the district height limits, so long as the height does not exceed the distance to the property lines. The exemption is written as agricultural buildings but not including dwellings. It is the same line the state statute draws when it exempts nonresidential farm buildings from the statewide standards, and it closes the moment the building contains somewhere to live.
Where the land is: 83% of Wilson County's land is unincorporated, and agricultural and open-space land is still about 74% of the county across more than 56,000 platted parcels. Pasture and grassland alone account for roughly 133,100 acres. Between 2001 and 2016 the county lost about 11,270 acres of farmland, 15% of all farmland loss in Middle Tennessee over that period, and the county projects a further 22,600 to 50,100 acres of loss by 2040.
Growth: Wilson County grew 66% between 2000 and 2020, from 88,809 to 147,737 residents, and stood at 175,033 as of 1 July 2025. It is the tenth most populous county in Tennessee and its own land use plan projects it will be ninth by 2045 at around 257,000. Mt. Juliet grew nearly 218% between 2000 and 2020 and Lebanon almost 90%, but since 2020 Lebanon has grown faster, and the county expects growth outside the municipal boundaries to accelerate.
Limestone, sinkholes and karst: About 65% of the county sits in the Inner Nashville Basin and the rest in the Outer Nashville Basin, on limestone-rich soils. The county's land use plan maps sinkholes, karst geology, steep slopes and flood hazard as its environmental constraints, and its rural agriculture place type names constrained lands of slopes and karst directly. Land is generally gentle, at 500 to 600 ft, with slopes over 15% limited mostly to the Cumberland River corridor and the south-east.
What a house costs to buy here instead: The county's own land use plan reports that in 2024 the typical single-family home in Wilson County was valued at approximately $483,000 according to Zillow, needing an estimated household income of $123,700 to afford, against a countywide median household income of about $94,000. Homeownership in the unincorporated area runs at 89% of households.

Below the slab

The expensive surprises are in the ground, not the building

What moves a Tennessee budget is usually below grade: limestone sitting shallow, karst voids and sinkholes, and slope. Those are the same conditions that decide whether a septic field passes its soil and site evaluation, so the grading plan, the footing depth and the drainfield get resolved together rather than one at a time. We price the dirt before we price the building.

What we build in Wilson County

All nine services are available across Wilson County. What a build costs depends far more on the parcel than on square footage, so we price against your land rather than publishing a rate card.

Barndominium Kits

Engineered barndominium shell packages delivered to your Tennessee lot, stamped for the criteria your county adopted.

Turnkey Builds

Start to finish barndominium construction: we handle permits, slab, shell, and full interior finish.

Custom Plans

Barndominium floor plans drawn to your land, your family, and the residential code your county actually enforces.

Post-Frame Homes

Pole barn construction adapted into full residences, with wide clear spans and fast dry-in.

Steel Construction

Red-iron and light-gauge steel framing: no rot, no termites, engineered to your county’s adopted wind criteria.

Shouses

Shop and house in one building: workspace and living space under a single roof and a single permit.

Metal Homes

Full metal-clad residences: low maintenance envelopes specified to your Tennessee climate zone.

Site Preparation

Clearing, grading, pad, drainage, and utilities: the work that decides whether the build goes smoothly.

Permitting & Engineering

Sealed structural engineering and the permit that depends on it, from submittal through final inspection.

What a build looks like

Three stages every Wilson County project passes through, from a raw parcel to a finished home. Site work first, because that is where the budget is decided.

Stage one

The parcel

Zoning, setbacks, flood zone and utility access get checked before anything is drawn.

Stage two

Pad and permit

Clearing, grading and a compacted pad, while the submittal works through Wilson County.

Stage three

Frame to finish

Shell erected and dried in, then systems, insulation and interior finish through to CO.

Those are the rules for Wilson County. Tell us what you want to build and we will draw it to them.

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Where we build around Wilson County

Wilson County and the rural land around it. The buildable acreage for a project this size usually sits outside the city limits, which is frequently what changes who issues your permit.

Our Wilson County service area, covering Wilson County and the surrounding rural acreage. We build across this area from our office in Franklin, TN — this map marks the territory we serve, not a branch location.

Keep reading

The questions that usually come next once you know what Wilson County allows.

Barndominium Cost Guide

Sourced per-square-foot ranges by tier and by size, with a calculator built on the same figures.

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Is It Legal in Tennessee?

Classification, zoning, the HOA gate, and why "nonresidential farm building" does not cover a home.

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How Long Does It Take?

Census build-duration data, and what actually sets the permit clock where you are building.

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Sources for this page

The primary documents behind the Wilson County figures above. We would rather you checked them than took our word for it.

Nearby areas we build in

Others we cover in this part of Tennessee. The permitting authority, the adopted design criteria and the zoning can all differ from one to the next.

Nashville

Davidson County

Sumner County

Rutherford County

Building in Wilson County: common questions

6 questions we get asked most often about building in Wilson County. If yours is not on the list, ask it directly.

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Can I build a barndominium in unincorporated Wilson County, and what zoning do I need?

Yes. The district you want is A-1 Agricultural, which lists a single-family dwelling first among its permitted uses, so no appeal to the Board of Zoning Appeals is needed for the house itself. The minimum lot area is 80,000 square feet, a little under two acres, and it is 80,000 whether the lot has public sewer, public water only, or neither, with a rider that the state environment department can require more after it looks at the soil. Lot width is 125 feet at the front building line where there is no public sewer. Setbacks are 60 feet from an arterial, 40 from a collector and 30 from a minor street, 20 feet at the side and 40 at the rear, and all buildings together can cover no more than 35 percent of the lot. R-1 Rural Residential also takes a house, on 40,000 square feet, with 15-foot side yards. Wilson County's ordinance does not use the word barndominium anywhere, so the building is simply a single-family dwelling for zoning purposes.

Does the county issue the permit, or does Lebanon or Mt. Juliet?

It depends on which side of a city line the parcel sits, and the answer changes the code edition your house is built to. The Wilson County Building Codes Department at 233 East Gay Street in Lebanon permits and inspects the unincorporated county, and it enforces the 2021 International Residential Code. The City of Lebanon and the City of Mt. Juliet each run their own building department and each hold their own exemption from the state, and both build houses to the 2018 IRC. So a parcel a mile outside Lebanon and a parcel inside it are on different editions of the residential code. Watertown is handled differently again, and the county office is the right first call there. Check the parcel before you get attached to a lot, because city limits in Wilson County follow annexation lines rather than anything you can see from the road.

Will the county make me put brick or stone round the bottom of the building?

If the finished floor sits above the surrounding grade, yes. Section 3.12.04 of the zoning ordinance requires every principal single-family dwelling with a finished floor elevation above the grade of the surrounding land to have a brick, stone, masonry or stucco panel curtain wall installed around the perimeter, enclosing the space underneath from just below the finished floor down to ground level, and left un-pierced except for required ventilation, utility connections and access. Which of those four materials is used is the applicant's choice. This is the single provision that a stock post-frame or pier-set package most often fails, because plain metal or vinyl skirting is not on the list. A slab-on-grade building whose finished floor is not raised above the surrounding land does not trigger the rule at all, which is one reason a slab is worth costing properly here. There is a narrow exception for temporary housing on the site while the permanent residence is built, but the curtain wall becomes due the moment there is no valid active building permit.

Can I clad the house in metal in Wilson County?

Yes. The county does restrict metal siding, but the restriction is in Section 3.55, which is headed Site Development and Landscaping Standards, Commercial and Industrial Zone Districts. Its first subsection applies within commercial zone districts and its second within industrial zone districts, and both are about elevations facing a public road on a commercial or industrial building. Neither reaches A-1, A-2 or R-1, and neither reaches a dwelling. The provision that does touch appearance on a rural residential lot is the accessory-building rule: a detached shop taller than 22 feet that sits on accessory setbacks rather than principal setbacks may go to 30 feet only if it matches the predominant two roof pitch angles and the building material of the house. So the constraint is on making the shop match the house, not on what the house is made of.

How much land do I really need, and who handles the septic?

Start at 80,000 square feet for the zoning, then treat that as a floor rather than an answer. Every minimum-lot-area subsection in A-1 carries the same rider, that a greater lot area may be required based on recommendations by the Tennessee Department of Environment and Conservation, and TDEC is the office that permits septic systems in Wilson County. The county states directly that its codes and zoning department does not permit or conduct septic inspections, so the soil and site evaluation and the permit come from the TDEC field office on 931-520-6688, and a septic permit or septic records is a checklist item before the building permit. Wilson County sits on limestone in the Nashville Basin and its own land use plan maps sinkholes and karst geology as constraints, so shallow rock is a real risk on a given parcel and it is the thing most likely to push the required area past the zoning minimum. Get the soil work started early, before the lot is bought if you can.

How long do I have to finish, and can I live in the shop while I build?

You have 24 months. A residential building permit in Wilson County cannot run longer than 24 months without a certificate of occupancy, and if the build is going to take longer you have to go to the Board of Zoning Appeals for relief. Moving in before the final inspection carries a $500 charge. Living in the shop is not an option the ordinance offers. A detached accessory dwelling unit is allowed, but it is capped at 1,000 square feet of total heated area, limited to one per property, has to have permanent utility connections and a permanent foundation meeting the same curtain-wall section as the house, and has to be signed off as code-compliant by the Chief Building Official. Travel trailers are prohibited as a permanent dwelling in A-1 outright, and the ordinance says the Zoning Administrator will not release electrical permits to connect one in place for an extended period. The legitimate route is temporary housing placed on the site while the permanent residence is built, which the foundation section contemplates directly.

What clients say

4.9 out of 5 based on 8 reviews Placeholder content

We had ten acres outside town and no idea what we could legally put on it. They pulled the zoning and the A-1 lot minimum before we spent anything on drawings, which saved us from buying plans for a building that would not have been approved.

Dale W. July 18, 2026

Ordered the shell kit and erected it with my brother-in-law over about six weekends. The drawings were clear, the bolt schedule matched what showed up on the truck, and the county inspector had no issues with the engineering.

Marisol T. June 2, 2026

Turnkey from a cleared lot to certificate of occupancy. What I appreciated most was that when plan review came back with comments, I heard about it the same day along with what they were doing about it.

Ray B. April 27, 2026

Building in Wilson County?

Start with the plan. Tell us what you want to build and we will draw it, then confirm what Wilson County will actually let you put on the parcel and what wind load it has to meet. That conversation costs nothing.

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