Johnson County No code adopted here

Barndominium Builders in Johnson County, MO

Johnson County is prairie farm country with an Air Force base in the middle of it, and those two facts settle almost everything about building here. The county commission puts its own position in writing and signs it: a letter dated 3 February 2026 from Presiding Commissioner Troy A. Matthews and Commissioners Rusty Sproat and Charles Kavanaugh states that "Johnson County, Missouri, does not have planning and zoning regulations, building codes, inspections, or occupancy certificates for unincorporated areas, except for properties located within the Whiteman Air Force Base Zoning Area." The county's Planning & Zoning page carries the same sentence with the words "building permits" added to the list. There is no county building department, no county building official and no county plan review. On a tract out in the sections, nobody from the county will look at your framing, your footings, your roof or your wiring. That is a choice, not a legal ceiling. Johnson is a fourth-classification county on the Missouri Association of Counties list published May 2025, and RSMo 48.020 provides that such a county "shall remain a county in the second classification and shall operate under the laws of this state applying to the second classification." RSMo 64.205 provides that sections 64.170 to 64.200 — the building-code sections — "shall apply to all counties of the first and second class." So the commission could put a building code on the ballot. It has not. Only twenty-five of Missouri's 114 counties are in that position at all; the other eighty-nine are third classification and could not adopt one if they wanted to. A buyer should know which kind of "no code" this is, because one can change at an election and the other cannot. The exception is the interesting part, and there is nothing else like it in the state. RSMo 41.655 — the Revisor's own catchline reads "Planning and zoning for unincorporated areas near military bases — airport hazard area zoning required (Johnson County)" — directs the county to "provide for the planning, zoning, subdivision and building" in the unincorporated area extending three thousand feet outward from the base boundary and inside the perimeter of accident potential zones one and two. The county did it: the 2015 Military Airport Zoning Ordinance and Subdivision Regulations, first printed 19 February 2009, amended 12 March 2015, approved by the Johnson County Commission 16 March 2015 and enacted 15 April 2015. Inside that area it is unlawful to build a structure of 500 square feet or more without a Military Airport Zoning Clearance from the county's Zoning Administrator, and the ordinance is administered from Pioneer Trails Regional Planning Commission in Concordia with quarterly public meetings at Knob Noster City Hall. It limits you to one single-family dwelling per three acres, five acres inside the AICUZ overlays — and in the APZ-1 and APZ-2 overlay districts residential development is simply "not permitted." Outside that footprint the ordinance reaches nothing at all. What does gate a build on ordinary Johnson County ground is the septic permit, and it bites harder here than the state minimum. The Missouri Department of Health and Senior Services records Johnson County Community Health Services at 723 PCA Road in Warrensburg as an Ordinance authority, and the Johnson County Code of Health Regulations, effective 1 July 2016, says in terms that it "does not allow an acreage exemption for the construction or major modification of an OWTS." The three-acre exclusion in RSMo 701.031 does not help you here. A soil morphology evaluation is required on every site regardless of system type, the permit is $200, and final approval waits on a 911 address — which the Assessor's Office assigns only to a structure, never to bare land. Add a floodplain development permit from the same office if the parcel touches a mapped hazard area, a driveway permit from Road and Bridge if the access is off a county road, and that is the whole county-level chain. The cities are a different country. Warrensburg runs the 2024 International Building Code and the 2024 International Residential Code with permits, plan review and inspections; Holden runs the 2015 family; Knob Noster is still on the 2003 editions. Three code generations twenty-one years apart inside one county line, plus unincorporated ground under none of them. Where you buy decides which of those four answers applies to you, and it is worth knowing before the contract, not after.

Johnson County at a glance

County: Johnson County
Population: 55,880
ZIP codes: 64093, 65336, 64040, 64019, 65305, 64761, 64733, 64061, 65360, 64747
Site visits: Same-week site visits across Johnson County — Warrensburg and the University of Central Missouri campus edge, Knob Noster and the Whiteman gate, Holden and Kingsville out west on Highway 58, Centerview, Leeton and Chilhowee, and the section-road country on either side of Highway 13 and Highway 50

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Building conditions in Johnson County

Missouri sets no residential building code and no statewide way of adopting one, so the first question on any parcel is not what the code says — it is whether there is one. Only counties of the first and second classification may adopt a building code at all, and classification is set by assessed valuation rather than population, so a small county can hold the power while a much larger one does not. Zoning is a separate power with its own answer, granted only after a vote of the people and repealable by another. What changes from one jurisdiction to the next is whether the work is inspected, who issues the permit, what that office charges, how the parcel is zoned, and the design figures your drawings have to satisfy.

Build conditions for Johnson 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.

A fourth-classification county that could adopt a code and has not

Johnson County appears in the fourth classification on the Missouri Association of Counties list published May 2025, one of only four counties in that group. Fourth classification is not a smaller kind of authority — RSMo 48.020 provides that such a county "shall remain a county in the second classification and shall operate under the laws of this state applying to the second classification," and the association's own list prints the note "CLASS 4 COUNTIES OPERATE UNDER THE LAWS OF CLASS 2 COUNTIES." Since RSMo 64.205 applies the building-code sections 64.170 to 64.200 to "all counties of the first and second class," Johnson County may lawfully put a building code in place. It has not. That is a different answer from the eighty-nine third-classification counties, which have no such power at all, and the difference is worth understanding: this one can change at an election.

Missouri Association of Counties, "Missouri Counties by Classification," published May 2025 (mocounties.com/s/Missouri-Counties-by-Classification-2025.pdf), downloaded and read 8 September 2026: Class 4, total 4 — Johnson, Lafayette, Pettis, Saline, with the printed note on class-4 counties operating under class-2 law; RSMo 48.020 Classification 4 (Effective 28 August 2026); RSMo 64.170.1 (Effective 28 August 2008); RSMo 64.205 (Effective 28 August 1963), all read on revisor.mo.gov 8 September 2026

The county commission signs a letter saying there is no code

Johnson County publishes a signed letter from its three commissioners, dated 3 February 2026, that a lender or a title company can be handed directly: "At this time, Johnson County, Missouri, does not have planning and zoning regulations, building codes, inspections, or occupancy certificates for unincorporated areas, except for properties located within the Whiteman Air Force Base Zoning Area." The county's Planning & Zoning page carries the same sentence with "building permits" added to the list. The letter then routes the reader through the things that do apply — recorded subdivision covenants from the Recorder of Deeds, city zoning inside city limits, addressing and floodplain permits from the Assessor, onsite wastewater from Community Health Services, driveways from Road and Bridge, and right-of-way work within thirty feet of a county road centreline from the Commissioners.

Johnson County Commission, "Re: Zoning for Johnson County, Missouri," letter signed by Presiding Commissioner Troy A. Matthews and Commissioners Rusty Sproat and Charles Kavanaugh, dated 3 February 2026, published at jocomo.gov/DocumentCenter/View/656; and Johnson County Planning & Zoning page, jocomo.gov/212/Planning-Zoning, both read 8 September 2026 and the page re-read on an independent navigation the same day

Whiteman Air Force Base: a state statute that names this county

RSMo 41.655 is written for Johnson County and the Revisor's catchline says so — "Planning and zoning for unincorporated areas near military bases — airport hazard area zoning required (Johnson County)." It directs the county to "provide for the planning, zoning, subdivision and building" in the unincorporated area extending three thousand feet outward from the base boundary and within the perimeter of accident potential zones one and two. The county did it. The 2015 Military Airport Zoning Ordinance and Subdivision Regulations makes it unlawful "to construct, alter, or to commence the creation, construction, alteration, or use of a building or structure of 500 square feet or more, without obtaining a Military Airport Zoning Clearance" inside that area. There is no agricultural exemption from that clearance. It caps you at one single-family dwelling per three acres, five acres inside the AICUZ overlays. And in the APZ-1 and APZ-2 overlay districts residential development is "not permitted" outright — a house is not a use you can apply for there. This is the only ground in the county that is zoned at all.

RSMo 41.655, Title V, Chapter 41, Effective 28 August 2007 (L. 2005 H.B. 348 § 41.1013 merged with S.B. 252 § 41.1013, A.L. 2007 S.B. 22), revisor.mo.gov, read 8 September 2026; The 2015 Military Airport Zoning Ordinance and Subdivision Regulations for the Unincorporated Area of Johnson County, Missouri, published by the Johnson County Airport Zoning Commission — first printing 19 February 2009, amended 12 March 2015, approved by the Johnson County Commission 16 March 2015, enacted 15 April 2015 — Sections 102, 103, 301, 502, 1105, 2102, 2202 and 2302, downloaded from trailsrpc.org and read 8 September 2026, then re-downloaded and the load-bearing sections re-read (identical file checksum)

The septic ordinance deletes the three-acre exemption

The state's onsite wastewater programme excludes a single-family lot of three acres or more under RSMo 701.031. That exclusion does not operate in Johnson County. The Johnson County Code of Health Regulations, effective 1 July 2016, states at Section 3.2.5.1 that the code "does not allow an acreage exemption for the construction or major modification of an OWTS," and the health department's own brochure asks the question and answers it: "Is there an acreage exemption in the OWTS ordinance? No, all installations and major modifications require a permit, approval prior to construction and a final inspection." The three-acre figure survives only as a licence exemption at Section 3.2.6.2, letting the owner of a three-acre-plus lot run the excavator himself — and that section says in terms it "shall not exempt any person from the requirement to obtain a permit." The permit is $200 and a soil morphology evaluation is required on every site whatever system you are putting in, because, as the department puts it, "many of the soils in Johnson County are unsuitable for OWTS due to rock, groundwater, and clay content."

Johnson County Code of Health Regulations, current version effective 1 July 2016, Sections 3.2.4, 3.2.5.1, 3.2.6.1 and 3.2.6.2, and the Johnson County Community Health Services onsite wastewater brochure, both downloaded from johnsoncountyhealth.org and read 8 September 2026; Missouri Department of Health and Senior Services onsite wastewater construction permit process, county selector returning Johnson County Community Health Services, Authority Type Ordinance, 723 PCA Road, Warrensburg, queried 8 September 2026 with Camden run first as a known-good control; RSMo 701.031, Effective 28 August 2005, revisor.mo.gov

Three code generations inside one county line

Warrensburg adopted the 2024 International Building Code and the 2024 International Residential Code on 13 January 2025, effective 1 March 2025, with the 2023 National Electrical Code alongside them — and then kept the 2018 International Energy Conservation Code, re-adopting that edition by ordinance on the same night and deleting the 2024 IRC's own energy chapter to point at it. Holden runs the 2015 family: 2015 IBC, IRC, IPC, IMC, IFGC, IFC, IECC and IPMC, with the 2014 NEC. Knob Noster is still on the 2003 International Building Code and the 2003 International Residential Code, both adopted in May 2005. Unincorporated ground is under none of them. That is four different answers on one county map, and for a steel-skinned building the energy edition matters as much as the structural one, because the envelope specification is most of the job.

Warrensburg Code of Ordinances §§ 6-16, 6-19, 6-21 and 6-36 (Ord. Nos. 5927, 5928, 5929 and 5932, all § 1, 13 January 2025), codified through Ordinance No. 6023 enacted 13 April 2026, Supplement 41 Update 1, read via the Municode publication API 8 September 2026 and re-read on an independent request; Holden Code of Ordinances Chapter 40, Building Permits and Code Enforcement (ORD #04-18), Sections 40.020-40.095, holdenmo.gov, read 8 September 2026; Knob Noster Municipal Code §§ 500.010 and 500.150 (Ord. Nos. 708 and 709, §§ I-II, 17 May 2005), ecode360.com, page titles verified as "City of Knob Noster, MO" in the same read

Measured ground: shrink-swell clay, not Ozark rock — and nobody fixes a bearing value

The USDA soil survey of Johnson County covers 533,485 acres in 83 map units. On 301,608 component-weighted acres — 56.5 percent of the survey — some horizon in the top metre carries a linear extensibility of 6 percent or more, which is where the shrink-swell rating turns from moderate to high; on 27,911 acres it reaches 9 percent or more. Just over half the survey is somewhat poorly drained or worse, and only 105,003 acres are rated well drained. The largest single map unit in the county is Sampsel silty clay loam, 5 to 9 percent slopes, severely eroded, at 79,493 acres; Sampsel runs to 48 percent clay with a linear extensibility of 9.7, and Haig, Snead and Polo are close behind. Bedrock sits within about forty inches on 127,636 weighted acres, 23.9 percent — computed the same way, Cass County one line west returns 17.2 percent and Pettis County one line east returns 1.5 percent, so this is not a figure to borrow across a county line. And no instrument anywhere in Johnson County fixes a presumptive soil bearing value: neither Warrensburg nor Holden amends IRC Table R401.4.1, and unincorporated ground has no code to amend. Cass County's own code assigns 2,000 psf to its typical clays; nothing here does. That makes a site-specific investigation the only basis for a footing or pier schedule on this ground.

USDA-NRCS Soil Data Access, sdmdataaccess.sc.egov.usda.gov, queried 8 September 2026 against survey area MO101 (Johnson County, Missouri), which returns 83 map units totalling 533,485 acres; shrink-swell from chorizon.lep_r for horizons beginning above 100 cm, weighted by component percentage; bedrock share from corestrictions where reskind is lithic or paralithic bedrock and resdept_r is 102 centimetres or less — resdept_r is recorded in CENTIMETRES, and 102 cm is about forty inches; the same query run against MO037 (Cass) and MO159 (Pettis) for a method-consistent comparison; bogus survey area MO999 returns an empty result as the control. Warrensburg Code § 6-20 and Holden Chapter 40 amendment lists checked for R401.4.1 and neither amends it

Also worth knowing before you build in Johnson County

Two cities, editions nine years apart, identical numbers: Warrensburg fills in Table R301.2(1) of the 2024 International Residential Code with 20 psf ground snow, 90 mph wind, no topographic effects, no special wind region, Seismic Design Category A, severe weathering, a 36-inch frost line, moderate-to-heavy termite, a 6°F winter design temperature, ice barrier underlayment required, an air freezing index of 1017, a mean annual temperature of 55.8°F and an elevation of 840 feet. Holden fills in the same table on the 2015 edition with 20 psf, 90 mph, Category A, Site Class D, severe weathering, a 36-inch frost line, moderate-to-heavy termite, 6°F, ice barrier not required, air freezing index 1000 and mean annual temperature 53°F. Two adopted tables, editions nine years apart, and snow, wind, seismic and frost are the same on both — the ice-barrier line and the freezing index are the only real movement. Knob Noster's ordinance says of Table R301.2(1) only "Insert: Ref: Attached," so the city's codified text carries no design figures at all, and unincorporated Johnson County has no adopted table for anyone to fill in.
Fire districts: checked by name, and neither runs a building code: In a county with no building code, a fire protection district can end up as the only construction authority on the ground — RSMo 321.220(12) lets a district board adopt ordinances whose standards may be industrial codes from nationally recognised trade bodies, and it is a route that has nothing to do with county classification. Both districts covering unincorporated Johnson County were checked by name and neither publishes an adopted building or residential code, a permit programme or an inspection programme. Johnson County Fire Protection District, formed in 1979, covers 520 square miles of the eastern two-thirds of the county, excluding the cities of Knob Noster and Warrensburg, from twelve stations. Johnson County Fire Protection District No. 2, voted into existence in April 1982 out of the old Western Jo-Co Fire Association, covers roughly 265 square miles of the western portion from Holden and takes in Jackson, Kingsville, Madison and Rose Hill townships. Two more rules bound the question anyway: RSMo 321.228 makes a district "without power, authority, or privilege" to run a residential construction regulatory system inside a city that adopts, implements and enforces one — which Warrensburg, Holden and Knob Noster each do — and RSMo 321.220(12) bars any district from requiring permits for farm buildings.
Exterior materials, roof pitch and design review: checked, and there are none: A steel-skinned house is banned outright in some Missouri jurisdictions, so the question is worth asking here — and the answer in Johnson County is that no instrument restricts it. The Military Airport Zoning Ordinance, the only zoning reaching any unincorporated ground, contains no exterior material rule, no roof pitch minimum, no eave requirement, no design review and no minimum dwelling floor area; what it regulates is density, height under the AICUZ map, and use. Warrensburg's Chapter 27 zoning carries no exterior material or pitch standard for a site-built dwelling either — the only material rules in the chapter are the skirting and masonry-pad requirements in the R-MH manufactured home district, and the only design review is a certificate of appropriateness inside the H historic overlay. Holden's Chapter 42 has none. Knob Noster's zoning regulations have none. What the cities do set is minimum floor area and what an accessory building may be: Warrensburg requires 800 square feet per dwelling unit in R-1 and caps accessory structures by height rather than by floor area — they may not exceed the height of the principal building, with no square-footage limit at all — while Holden requires 900 square feet of finished living space and expressly prohibits using an accessory building as a residential dwelling in any district without council approval.
The agricultural line falls in three different places here: In unincorporated Johnson County there is no building code, so there is nothing for a farm building to be exempt from — the question simply does not arise outside the Whiteman zoning area. Inside it, Section 502 of the Military Airport Zoning Ordinance requires a clearance for any structure of 500 square feet or more with no agricultural carve-out, though AR-1 and AR-2 both permit "accessory buildings for agricultural operations" and the density rule at Section 1105 does not count "additional support buildings for storage of equipment, farm usage, garages or shops." Holden draws the sharpest line of the three cities: its building code is amended so that "structures used exclusively for agricultural purposes on unplatted tracts of five (5) acres or more shall be exempt from this code" — note both conditions, exclusively agricultural and unplatted, which a house does not meet. Warrensburg has no agricultural exemption at all; the word does not appear anywhere in its building chapter, and farming excluding livestock is only a conditional use in its zoning. And under RSMo 321.220(12) no fire protection district may require a permit for a farm building anywhere in the state.
The 911 address is a real gate, and it comes last: In a county with no building permit, the address is the closest thing to one. The Assessor's Office assigns addresses in unincorporated Johnson County, and its published procedure says "before utilities can be connected or wastewater treatment permitted, an address may need to be assigned to the property," that addresses are assigned on the physical location of the structure and the road the driveway will connect to, and that "addresses are assigned only to structures; vacant or bare land will not be given an address." The health department closes the loop from the other end: "any new construction of an OWTS will not be granted final approval until the property has an address assigned." So the sequence on a raw tract is parcel card and aerial photo from the Assessor, soil morphology report, septic permit, driveway permit if the access is off a county road, address, then final septic approval. Nowhere in that chain does anyone inspect the building.
Which road you are on decides who permits the driveway: Johnson County publishes a field test that is genuinely useful on a rural showing. Roads marked with brown numbered road signs in the unincorporated county are privately owned and maintained, and access has to be arranged directly with the neighbouring owners — there is no county permit to get and no county obligation to maintain. Roads marked with green numbered road signs are county-maintained, and a driveway, field entrance or road entrance permit comes from the Road and Bridge Department at 335 E. North Street in Warrensburg after reviewing the county's right-of-way ordinance. Lettered and numbered state highways go to the Missouri Department of Transportation; named streets inside a city go to that city hall. Separately, any construction within thirty feet of the centreline of a county road or trail needs the county's right-of-way procedure through the County Clerk.
Farm country, and the tracts are large: The 2022 Census of Agriculture counts 1,526 farms in Johnson County holding 415,874 acres, at an average of 273 acres — the farm count is down but the average size is up 8 percent since 2017. Land in farms breaks down as 228,817 acres of cropland, 128,363 of pastureland, 39,447 of woodland and 19,247 of other. The Census Bureau gives the county 829.262 square miles of land and 3.929 of water. Farms by size run 73 under ten acres, 421 between ten and forty-nine, 508 between fifty and 179, 321 between 180 and 499, 129 between 500 and 999, and 74 above a thousand — which is to say the ten-to-fifty-acre band that a barndominium tract usually comes out of is the second-largest group in the county and there is no shortage of it.
Forty-one percent of the clear zone is private land under a federal easement: The Air Force's own AICUZ study for Whiteman records that the clear zones at each runway end are 3,000 feet wide by 3,000 feet long, APZ-1 is 3,000 by 5,000 and APZ-2 is 3,000 by 7,000 — and that "at Whiteman AFB, 41 percent of the clear zone property is located off base and is subject to restrictive easements." That is the pattern worth understanding before buying near the base: the owner holds title, pays the taxes, and cannot build. The study's land-use table marks single-family detached dwellings incompatible in the clear zone and in both accident potential zones, and allows them in the DNL 65-70 and 70-75 dB noise contours only with 25 and 30 decibels of noise level reduction built into the structure. The base itself occupies 4,183 acres two miles south of Knob Noster and ten miles east of Warrensburg, hosting the 509th Bomb Wing and its B-2s, the reserve 442d Fighter Wing's A-10s and a Missouri Army National Guard aviation unit.
No county contractor licence, and only two trades licensed anywhere: Johnson County licenses no contractors of any kind — there is no county building office to issue one, and Missouri has no statewide general contractor licence to hold instead. Warrensburg comes closest, and it is narrower than people expect: § 6-1 of its code requires anyone providing plumbing or electrical service to the public to pass an examination administered by the building official, at a $65 examination fee, and that is the whole scheme. There is no general contractor class, no residential contractor class and no bond or insurance requirement attached to one. What Warrensburg does require of any build is a boundary survey by a licensed professional land surveyor before the site location inspection, and sealed plans from a Missouri-licensed engineer for any residential solar photovoltaic installation.

Below the slab

The expensive surprises are in the ground, not the building

What moves a Missouri budget is usually below grade, and which problem you have depends on where in the state you are. Across the Ozarks it is karst: the Department of Natural Resources maps more than sixteen thousand sinkhole points, and what matters there is what is under the slab rather than what the slab sits in. Across the north and centre it is claypan — dense, slow-draining subsoil that perches water above it for months of the year. In the Bootheel it is deep alluvium carrying the highest seismic demand in the state, where the same soils modelled for liquefaction attack post embedment and slab bearing rather than the frame above them. The same ground then decides the septic system, and Missouri does not run that on a percolation test alone: the rule allows a perc test or a soil morphology examination in a profile pit, and the authority reviewing your parcel picks which. Where a drainfield sits near a sinkhole's drainage, perc testing on its own is not permitted at all. Whether that authority is the state or your own county is itself a local question, and it changes what you have to file. So the site work, the foundation 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 Johnson County

All nine services are available in Johnson 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.

Custom Plans

Barndominium floor plans drawn to your parcel and your soil, and to whichever Missouri authority — a county, a city, or none at all — will review them.

Barndominium Kits

Barndominium shell packages delivered to your Missouri land, drawn to the criteria your own county or city publishes — because the state publishes none.

Turnkey Builds

Start to finish barndominium construction in Missouri: the permits that genuinely apply, site work, shell and interior finish, under one contract.

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What a build looks like

Three stages every Johnson 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 whichever office issues the permit where you are building.

Stage three

Frame to finish

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

Those are the rules where you are building in Johnson County. Tell us what you want to build and we will draw it to them.

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Where we build around Johnson County

Johnson 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.

The Johnson County service area, including the rural acreage outside the built-up edge, which is where the parcels big enough for a build like this usually sit. The map marks the territory we build in. It is not a branch location, and there is no office at this pin.

Keep reading

The questions that usually come next once you know what Johnson 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 Missouri?

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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Nearby areas we build in

Others we cover nearby, and they are not interchangeable. One may be a county with an adopted building code, another a county with no legal authority to have one, another a city that permits inside its own limits whichever county the land sits in. So the office that issues the permit, whether anyone inspects the work at all, the fees, the zoning and the design figures can differ from one card to the next — sometimes across a single property line.

Cass County

Lafayette County

Sedalia

Pettis County

Building in Johnson County: common questions

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

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Do I need a building permit to put up a barndominium in unincorporated Johnson County?

Almost certainly not for the building itself. The county commission signed a letter on 3 February 2026 stating that Johnson County has no planning and zoning regulations, building codes, inspections or occupancy certificates for unincorporated areas, and the county's Planning & Zoning page adds building permits to that list. There is no county building department to issue one. The exception is the Whiteman Air Force Base zoning area — the unincorporated ground within three thousand feet of the base boundary plus everything inside accident potential zones one and two — where the 2015 Military Airport Zoning Ordinance makes it unlawful to build any structure of 500 square feet or more without a Military Airport Zoning Clearance from the county's Zoning Administrator. Inside Warrensburg, Knob Noster, Holden, Centerview, Chilhowee, Leeton or Kingsville, the city permits and inspects and the county's answer is irrelevant.

My lot is over three acres. Does that get me out of the septic permit?

No. That exclusion is in RSMo 701.031 and it applies to the state programme, but Johnson County runs its own ordinance instead. The Johnson County Code of Health Regulations, effective 1 July 2016, says at Section 3.2.5.1 that the code "does not allow an acreage exemption for the construction or major modification of an OWTS," and the health department's brochure asks the question directly and answers no. The three-acre figure survives only in Section 3.2.6.2, which lets the owner of a three-acre-plus single-family lot operate the excavation equipment himself without an installer's licence — and that section says in terms it does not exempt anyone from getting the permit. Budget $200, a soil morphology evaluation from a certified soil scientist on every site whatever the system type, and a final inspection before the system is covered.

How close to Whiteman is too close?

It depends on which line you are behind, and the lines are drawn on a map rather than by distance. Inside the clear zones — 3,000 feet square off each runway end — above-ground structures are severely restricted and generally not permitted, and the Air Force's own study records that 41 percent of that clear zone land is privately owned and carries a restrictive easement, meaning the owner holds title and still cannot build. Inside the APZ-1 and APZ-2 overlay districts the county ordinance says residential development is not permitted at all. Elsewhere in the zoning area you may build a single-family dwelling, but at no more than one per three acres, or one per five acres inside the AICUZ overlays, with a height cap from the ordinance's Maximum Height Restriction map and a clearance required for anything 500 square feet or larger. The seller also has to hand a buyer a disclosure statement naming the ordinance and the noise exposure. Check the address against the county's Whiteman Air Force Base Zoning Viewer and the official map filed with the County Clerk before you write an offer.

Does anything stop me putting metal siding and a metal roof on the house?

Nothing in Johnson County does. The Military Airport Zoning Ordinance, which is the only zoning touching unincorporated ground, contains no exterior material rule, no minimum roof pitch, no eave requirement and no design review; it regulates density, height and use. Warrensburg's zoning chapter carries no material or pitch standard for a site-built dwelling either — its only material rules are skirting and masonry-pad requirements in the manufactured home district, and its only design review is a certificate of appropriateness inside the historic overlay. Holden and Knob Noster have none. What the cities do set is a minimum size: 800 square feet of dwelling area per unit in Warrensburg's R-1, and 900 square feet of finished living space in Holden.

Can I build the shop first and live in it while the house goes up?

Out in the unincorporated county there is no occupancy certificate to withhold, so nothing at the county level speaks to it — but the septic permit does, and the health department will not give final approval until the property has a 911 address, which the Assessor assigns only to a structure. Inside the Whiteman zoning area the ordinance takes a specific position: support buildings for equipment storage, farm use, garages and shops are not counted against the one-dwelling-per-three-acres density rule, and one outbuilding within 100 feet of the residence may contain one bedroom and one bathroom for a family member or guest and still be treated as part of the single-family dwelling. Inside Holden it is expressly prohibited to use an accessory building as a residential dwelling in any district without council approval. Warrensburg caps accessory structures by height rather than area — they may not exceed the height of the principal building — and inspects them like anything else.

What ground am I building on, and how deep do the footings go?

Western Missouri prairie clay, and it moves. The USDA soil survey of the county covers 533,485 acres, and on 301,608 of them — 56.5 percent, weighted by component — a horizon in the top metre carries a linear extensibility of 6 percent or more, the threshold where shrink-swell is rated high. Just over half the survey is somewhat poorly drained or worse. The largest map unit in the county is Sampsel silty clay loam, which runs to 48 percent clay. Bedrock sits within about forty inches on roughly a quarter of the survey. Both cities that publish a design table set the frost line at 36 inches, and Warrensburg adds its own rule that trench footings under a single-storey monolithic slab be a minimum of 36 inches deep and 8 inches wide, on undisturbed soil with no fill dirt unless the fill is compacted to 98 percent and tested. No instrument anywhere in Johnson County fixes a presumptive soil bearing value the way Cass County's code does, so a site-specific soils investigation is what a footing or pier schedule should be sized from.

Who actually inspects anything, if the county does not?

On unincorporated ground: the health department inspects the septic system before it is covered, and that is the only construction inspection that reaches the whole county. The Assessor issues floodplain development permits where the parcel is in a mapped hazard area — Johnson County has been in the National Flood Insurance Program since its initial flood insurance rate map of 2 April 1990, with the current effective map dated 4 July 2011. Road and Bridge inspects the driveway where it meets a county-maintained road. Inside the Whiteman zoning area the county's Zoning Administrator reviews the clearance. Both fire protection districts covering the county were checked by name and neither runs a building code, a permit programme or an inspection programme, so the framing, the foundation, the roof and the wiring are not reviewed by anybody unless you build inside a city. That is a reason to be deliberate about who you hire and what the drawings say, not a reason to relax.

Building in Johnson County?

Start with the plan. Tell us what you want to build and we will draw it, then confirm which office issues the permit for your parcel, what it will let you put there, and what wind load it has to meet. That conversation costs nothing.

Start your project