Barndominium concrete slab Oklahoma | Shop slabs

Barndominium concrete slabs in Oklahoma: one slab, two jobs

A barndominium concrete slab in Oklahoma has two jobs to do. The living side needs a flat floor that’s ready for a finish. The shop side needs thick concrete and heavy steel for lifts and trucks. We pour both in one slab: 4 to 6 inches on the living side, 6 to 8 inches on the shop side. It runs $5.32 to $15.61 a square foot, plus the drive cost (our trip to your site).

The metal building gets planned down to the last bolt. The slab often rides along as an afterthought, right up until someone notices the two sides need two different specs. On the living side, we pour to FF 50, a floor flatness score where higher means flatter. On the shop side, we set #4 rebar on 12-inch centers for equipment loads.

What is a barndominium slab, and how does it compare with a house foundation?

A barndominium slab is the foundation and the finished floor in one. It’s a single slab of concrete under a metal building. That building holds a home on one side and a work space on the other. Unlike a house with a crawl space or a basement, the slab sits right on packed dirt and gravel. It carries the steel frame at the outside columns, the inside walls, and everything that walks or rolls across it.

Oklahoma makes that job harder in three ways. First, much of the state sits on clay that swells when wet and shrinks when dry, called expansive soil. In wet spells, clay in central Oklahoma can push up on a slab with 1,500 to 4,000 pounds per square foot. Second, we get 60 to 70 freeze-thaw cycles a year. Third, each county sets its own footing depth, from 18 to 36 inches, based on the frost line and the soil type.

We’ve seen slabs poured on raw clay start heaving inside 5 years. On the same road, slabs that got the gravel and packing step right are still flat at 25 years. That gap is why the dirt work isn’t optional. Neither is a gravel layer that stops ground water from wicking up into the slab, called a capillary break.

Compared with a garage slab or an interior slab, a barndo slab is bigger and split in two. Most run 1,200 to 6,000 SF. They carry frame loads at the edges. And one pour has to serve a finish-ready living area and a tough shop floor. A floor that will be polished or coated also needs a vapor barrier. It goes right on the gravel base, not between layers of concrete, per ACI 302.1R.

What barndominium and shop slabs do we pour?

Barndominium and shop slab jobs across Oklahoma fall into four groups:

• Barndominiums (living plus shop). This is the most common job. It’s a metal building with a home on one side and a shop, garage, or storage on the other. Slabs run 1,200 to 6,000 SF. The living zone gets the SPEC build for a polished or coated floor, and the shop zone gets thicker concrete and more steel for equipment.
• Shop pads and metal building slabs. These are stand-alone shops for car restoration, welding, woodworking, or farm equipment storage. Common sizes run from 30x40 to 60x100, 6 to 8 inches thick with #4 rebar on 12-inch centers. Many get epoxy flooring or sealed concrete to stand up to chemicals.
• Equipment pads. These smaller pads, 10x10 to 20x30, sit outside the main building for generators, compressors, HVAC units, or welding stations. Most are 6 to 8 inches thick, with thicker edges to hold anchor bolts.
• Grain bin pads. These round or square pads hold grain bins. The thickness is engineered to the bin’s size and the weight of the grain, usually a 40 to 60 PSF load (pounds per square foot). We pour a lot of these between Prague and Stroud.

How much does a barndominium slab cost by size in Oklahoma?

Barndominium slab prices in Oklahoma depend on size, thickness, steel, and soil. The table shows the most common sizes. Each total covers the slab itself, before the drive cost.

The low end of each range is a plain 4-inch slab with wire mesh. The high end takes the top pick in each choice on the quote. That means the SPEC pour, rebar, the 15-mil vapor barrier, and a 7-day wet cure. Both ends assume 4 inches. For a 6- or 8-inch shop side, the quote tool prices that thickness. Rural sites with long drives, poor soil, or tight access cost more for the drive and the site work. The quote tool shows the drive cost for your address. Our 40x60 concrete slab cost guide walks through the size we get asked about most.

How thick should a barndominium slab be, and what steel goes in it?

One thickness doesn’t fit the whole building. The living side needs a flat surface for the finish. The shop side needs mass and steel for heavy loads. Pour them to one spec, and it shows up later. That’s when the flooring crew blames the slab for a finish that won’t lay flat. Before you sign with anyone, check the bid. Does it call out two zones, or just one number for the whole building?

Living zone (4 to 6 inches):

• 4 inches at least, for light home use
• 5 to 6 inches if you plan polished concrete, since grinding takes 1/16 to 1/8 inch off the top
• #4 rebar on 18-inch centers, or 6x6 welded wire mesh
• FF 50 or better for the SPEC build. You’ll see the FF number on bids, and most standard pours only hit FF 25 to 30.
• A 15-mil vapor barrier under any finished floor

Shop and equipment zone (6 to 8 inches):

• 6 inches for general shop use (trucks, hand tools, storage)
• 8 inches for heavy gear (floor jacks, lifts, CNC machines, grain handling equipment)
• #4 rebar on 12-inch centers, both ways
• 4,500 PSI concrete or stronger, so the top stands up to wear (PSI is how hard the concrete gets)
• Floor drain pipes set before the pour, because adding a drain later costs five times more

Edges and footings:

• Thicker edges, 12 to 18 inches deep, to carry the metal building’s column loads
• Anchor bolts for the frame, set to the building maker’s plan
• Footing depth per county code, 18 to 36 inches in Oklahoma based on the frost line

Steel options side by side:

Rebar on 12-inch centers and post-tension cables are priced per job. We set that steel plan after we see the building plan and the soil. Post-tension cables are steel cables pulled tight inside the slab. They let a big slab go 50 feet or more without joints.

What’s included, from the dirt to the cure

Every barndominium slab we pour follows the same six steps. They’re built for Oklahoma clay and a floor that’s ready to finish. Our aim is FF 50 or better on the living side. We also want the shop side ready for equipment about 7 days after the pour. Three of the steps carry the four names of our Pour-4-Polish spec: Set, Portland, Even, and Cure.

1. Dig and pack the ground (Set). We dig past the topsoil and roots to firm soil. We pack it in 6-inch layers to 95% Modified Proctor, the lab test for how tight packed dirt should be. Then we lay at least 4 inches of packed gravel, which stops water from wicking up and gives the slab a firm bed. On bad clay, we may call for 6 to 8 inches of gravel or soil treated with lime.

2. Vapor barrier and pipes. A 15-mil vapor barrier (Stego Wrap or equal) covers the whole footprint. That’s the shop side too, not just the living side. Plumbing, electrical conduit, and in-floor heat tubing all go in before the steel. We mark each floor drain and set it to grade.

3. Forms with two thicknesses. The forms follow the building’s footprint. Edges get thicker at the columns. Where the living and shop zones meet, we form a step, so each zone gets the thickness it needs. Then we check every form for level and square against the building’s anchor bolt layout.

4. Steel. Rebar or mesh sits up on chairs, so there’s 2 inches of concrete under it. Each zone gets its own steel plan. We tie the rebar at every crossing and overlap each splice by at least 40 bar widths.

5. Pour, finish, and cut joints (Portland and Even). Concrete goes in by pump or right off the truck chute, based on how we can reach the site. Power trowels bring the living side to FF 50 or better, the SPEC build. The shop side gets a standard finish. We usually saw-cut control joints within 12 hours, a quarter of the way through the slab. That way, cracks form in the cuts instead of across the floor. We space the joints about 2 to 3 times the slab’s thickness in inches, read as feet. So a 4-inch slab gets a joint about every 8 to 12 feet.

6. Water cure (Cure). The slab stays wet for seven days under soaker hoses and plastic sheeting. We put no spray-on curing compound on any zone that will be coated or polished. Those sprays leave a film a finish can’t grip, and it has to be ground off before anything will stick. Skip this step, and a finish-ready slab turns into a costly prep job later.

Who a barndominium slab is right for

This service fits when you’re building on rural land and want one concrete contractor for the whole foundation. It’s a good fit if:

• You’re building a barndo or metal building home and want the living floor ready for polished concrete or stained concrete from day one
• You need a shop slab that takes trucks, lifts, or heavy gear without cracking
• You want one contractor for the slab and the finish (pour plus polish, or pour plus epoxy) instead of lining up two crews
• Your site is along the I-44 corridor or within about 2 hours of Prague, OK, where sending two crews costs a lot more
• You’re pouring a grain bin pad, an equipment pad, or a stand-alone shop on farm land

This isn’t a driveway or patio pour. For those, see concrete driveways or concrete patios. For a regular attached garage, see garage slabs. For warehouse or retail slabs over 10,000 SF, see commercial flatwork.

How long does a barndominium slab take in Oklahoma?

Most barndominium slabs in Oklahoma take 2 to 5 days of work, based on size. Then the slab needs cure time before the next trade starts.

Before the pour: 1 to 3 days. This covers digging, compaction tests, gravel, the vapor barrier, pipes, forms, and steel. Slabs of 4,000 SF or more can take 2 to 3 days of prep.

Pour day: 1 day for most jobs. The trucks arrive, and we place the concrete by pump or chute. We vibrate it, screed it flat, trowel it, and saw the joints. A 40x60 slab (2,400 SF) is usually a one-day pour. A slab over 4,000 SF may take two days, with a construction joint where the two days meet.

Cure: 7 to 28 days. We water cure for 7 days. You can walk on it at 48 hours and drive on it at 7 days. The metal building can go up on the shop zone at 7 days. Polished concrete grinding waits at least 10 days before the first cut. Coatings (epoxy and polyaspartic) wait the full 28 days, because resin bonds to a slab that’s done giving off water, not one that’s still drying out.

Can we pour a storm shelter slab and the in-slab shelter opening?

Tornado country runs through every county where we pour barndos. So shelter questions come up on a lot of rural builds. We pour the concrete side of a storm shelter as part of the same one-piece slab. It gets the same two-zone thickness and clay prep described above. That work has three parts.

The ground under the shelter. A below-ground shelter or a bolt-down safe room changes the load on that part of the floor. We dig out and pack the shelter footprint to the same 95% Modified Proctor as the rest of the base. The gravel layer runs through it too. If the shelter pad settles at a different rate than the slab around it, the seam between them cracks. On expansive clay, the shelter zone gets the same deeper gravel or lime-treated soil as the rest.

The shelter opening, poured with the slab. An in-ground shelter sits below the floor. For that kind, we form the opening and pour it with the main slab. That includes the floor around it and the thick ring. It also includes the recessed lip the lid or door frame sits in. Pouring it all at once keeps the steel unbroken around the opening. Cutting into a finished floor and patching it later leaves a cold joint. That’s a seam where water can leak into the shelter.

Thick edges for the anchors. An above-floor rated safe room or a garage in-ground unit bolts to the concrete. Those anchors only hold if the concrete around them is thick and has steel in it. So we thicken the slab to 8 inches or more at the anchor edge and set #4 rebar around the bolt pattern. Before the pour, we match the bolt layout to the shelter maker’s template. It’s the same way we set the metal building’s column anchors.

The line between our work and the shelter’s work is a hard one. Bel Covo pours three things: the packed pad under the shelter, the opening and thick ring for an in-ground shelter, and the thick, steel-filled edge that an above-floor safe room bolts into. Each one gets the same care as the rest of a barndominium slab. That means dirt packed to 95% Modified Proctor, a gravel layer under it, steel that runs unbroken around every opening, and anchor bolts matched to the maker’s template before any concrete goes in. We don’t design, build, rate, or warrant the shelter itself. The rated room is the steel or concrete box that has to meet FEMA P-361 or ICC 500, the federal and building code standards for storm shelters. A licensed storm-shelter installer builds and certifies that room. We deliver the concrete the shelter sits on and bolts to. The installer delivers the room that carries the rating.

Oklahoma has at times run a state safe-room rebate program called SoonerSafe. It opens sign-ups in short windows. The amounts and dates change, so check the current program with Oklahoma Emergency Management before you count on it.

What moves the price of a barndominium slab?

The range on a barndo slab is wide. These jobs vary more than almost anything else we pour. A basic 30x40 shop pad at 4 inches with wire mesh sits at the low end. The high end is a 60x100 barndo with two thicknesses, rebar, and a SPEC-built living side, on a rural site 60 miles out. Get every one of the items below in writing before you sign. Some jobs end up 15 to 25 percent over the first number. Almost always, someone assumed a cost instead of quoting it.

Here’s what moves the number:

• Size. Bigger slabs cost less per square foot, because setup and the drive spread over more floor.
• Thickness. Each extra inch is more concrete in every square foot, and the quote tool prices that thickness.
• Steel. Rebar on 18-inch centers adds $1.49 a square foot over wire mesh. Rebar on 12-inch centers is priced per job, once we know the loads.
• The SPEC build on the living side. The SPEC pour, with its stronger mix and FF 50 flatness, adds $0.64 a square foot over a standard pour. The 7-day wet cure is its own line on the quote.
• Vapor barrier. The 15-mil barrier adds $0.60 a square foot.
• Site. Rural access, soil repair, and the distance from Prague, OK all change the drive cost.
• Post-tension cables. These are priced per job, since the cable layout comes from the building plan.

A shop-only slab and a full barndo slab of the same size land in the same range. Inside that range, the steel and the finish prep move the number. Whether one side of the building is a house doesn’t.

Get your price in about 2 minutes with our online quote tool. It counts size, thickness, steel, finish prep, and the drive from our shop in Prague, OK.

See finished barndominium and shop slabs

Our project gallery shows finished barndominium and shop slabs across central Oklahoma. You’ll find two-zone living and shop pours, stand-alone metal building slabs, and grain bin pads.

Where in Oklahoma do we pour barndominium slabs?

We pour barndominium and shop slabs across central and eastern Oklahoma from our shop in Prague:

• The Oklahoma City metro and nearby towns
• The Tulsa metro and Creek County
• Edmond, Norman, and Broken Arrow
• Towns along I-44: Stroud, Chandler, Bristow, Sapulpa, and Kellyville
• Rural land within about 2 hours of Prague, OK

Barndo builds along I-44 between Oklahoma City and Tulsa are our most common job. Prague sits about 20 miles south of I-44, close to the halfway point between the two cities. That’s part of why our drive cost to those towns tends to run lower than a crew coming out from either metro.

Should you bundle the slab and the floor finish into one job?

The slab is only half the job. We’ve watched enough of these go sideways to know the pattern. A finish contractor lays a polish or a coating over someone else’s pour, and it comes out soft or uneven. Then the slab guy and the finish guy spend a week pointing at each other instead of fixing the floor. One contractor for the pour and the finish ends that argument before it starts.

Living area. Pick the SPEC build of a Slab Boss Pour, and field and edge polishing on Slab Boss Polish cost 30% less than they do without it. When one spec governs the pour, the polished concrete finish costs less and looks better. The flatness and the cure the polish needs got built in from the start, not ground in after the fact. With one spec from the dirt to the sealed floor, nobody’s guessing whose mistake it was. Learn more on our Pour-4-Polish page.

Shop and garage side. Epoxy flooring or sealed concrete guards the shop floor from oil, chemicals, and tire marks. It makes cleanup fast, too. It goes on after the full 28-day cure, on the same trip as the living-side finish.

Bundling also means one drive cost instead of two, which matters most on rural sites far from town. One pour, one finish, and one workmanship warranty for the whole project. That’s the whole case for hiring one contractor.