A shop or barn slab carries a building and whatever rolls into it, so it is quoted in parts: field thickness, the thickened edge or turndown that carries the walls, the steel in each, the compacted pad it sits on, the vapor retarder if the inside will be finished, and the joint grid.
One independent, insured North Texas contractor will call or text within one business day to set a time to look at it. You get a written quote with the pattern, color, stone and slab spec on it.
Updated November 10, 2026
The building supplier's anchor-bolt and foundation drawing drives the edge detail.
A nominal 4-inch slab on well-drained, compacted fill is adequate for storage, light vehicles and a workshop; a pole-building supplier's guidance moves to 6 inches where heavy equipment will be driven and parked, noting that city streets and small airports run 4 to 7 inches. The same guidance puts the money in site preparation first: a thick slab over a poorly prepared subgrade is still a bad slab. Going from 4 to 5 inches raises load capacity substantially for roughly a fifth more concrete.
Source: Hansen Pole Buildings, concrete floor thickness for heavy equipment
A metal building sits on a perimeter that is thicker than the field, either a turned-down edge or a separate grade beam, with the anchor bolts set to the manufacturer's bolt plan. The residential concrete code, ACI 332, treats slab thickness, joints and reinforcement in its own chapter and footings separately, which is the structure a quote should follow: field, edge, steel in each. Verify the turndown depth, width and bolt layout against the building supplier's foundation drawing, and whether your city or an engineer requires a sealed design for the size of building.
Source: ACI 332-20, Code Requirements for Residential Concrete (preview)
Soft topsoil comes out; the pad is built up in compacted lifts of select fill or crushed stone so the finished floor sits above surrounding grade and water runs away on every side. On Blackland clay that pad and the drainage around it decide whether the slab stays flat. Fort Worth's parkway standard gives a usable benchmark for compaction language, 95 percent of standard Proctor, that you can ask for on any pad.
Source: City of Fort Worth, Parkway Standards
If the inside will be conditioned, floored, or used to store anything that cannot get damp, a vapor retarder goes directly under the slab. The residential code baseline is at least 6 mil between the base and the slab, with exceptions for unenclosed flatwork and small accessory structures; trade guidance goes further, recommending the membrane directly under the concrete rather than under a layer of fill, a minimum 6-inch overlap at seams taped and turned up at walls, and a 15-mil Class A sheet where trucks, pumps or buggies will drive on it. Ask the quote to name the mil thickness and ASTM E1745 class.
Source: For Construction Pros, selecting and installing vapor retarders under concrete floors
The code requires reinforcement to be supported in the top half to top third of the slab throughout the pour, which in practice means bars on chairs, not pulled up with a hook. Fort Worth's #3 rebar at 18 inches on center both ways on 3-to-3½-inch chairs is a representative residential call; heavier slabs and edges get larger bars per the engineer. Steel does not stop cracks, it holds the pieces together, so the joint grid still matters.
Source: EVstudio, IRC code requirements for concrete slabs on grade
The NRMCA's slab-on-grade guidance is contraction joints at 24 to 36 times the slab thickness, a maximum of about 15 feet, in panels as square as possible with no panel longer than 1½ times its width, cut to at least a quarter of the thickness and never less than an inch. Conventional saw cuts go in within 4 to 12 hours of finishing; early-entry saws run 1 to 4 hours after. Isolation joints separate the slab from columns and walls. Slabs that carry heavy loads get dowels at construction joints, carefully aligned.
Source: NRMCA Concrete in Practice CIP 6, joints in concrete slabs on grade
Four inches nominal for storage and light vehicles, six where heavy equipment parks, with the edge detail from the building drawing. Spend first on the pad.
If the inside will be conditioned, floored or used to store things that cannot get damp, yes: at least 6 mil by code, 10 to 15 mil Class A in practice, directly under the slab.
Usually the concrete crew, to the building supplier's bolt plan, before the pour. The quote should say so and name the plan.
It depends on the county. Collin and Ellis list barns and shops among projects that need a development permit; Tarrant and Parker issue no building permits; others permit development generally. See the county pages.
Pattern, color method, sealer, stone and joint, or field thickness, edge, steel, base and membrane: one independent, insured North Texas contractor looks at the lot and writes it all down with dates.
Residential and acreage, in eight DFW counties. No price on this site, because the lot and the drawing decide the price.
One independent, insured North Texas contractor will call or text within one business day to set a time to look at it. You get a written quote with the pattern, color, stone and slab spec on it.