How Much Does a 30x40 Concrete Slab Cost in Tennessee?
A 30x40 concrete slab — 1,200 square feet — is the most common foundation we pour for pole barns, metal buildings, and garages in Lawrence and Giles County. If you're planning a building and trying to figure out if the slab is a $6,000 job or a $15,000 job (you'll hear both), here's what's actually behind those numbers.
A 30x40 concrete slab pour in Lawrence County — vapor barrier, wire mesh, and electrical conduit stub-outs are part of our standard scope on every building slab.
Quick answer: 30x40 slab cost in Middle Tennessee
A 30x40 concrete slab (1,200 sq ft) in Lawrence or Giles County runs $10,000 to $16,000 installed for a 4-inch slab with wire mesh. Upgrade to 5-inch with rebar and you're at $13,000–$18,000. The range depends on subgrade conditions, base depth required, and whether site grading is needed. These are ACS's local numbers — not national averages.
Why the slab price varies this much
Soil conditions under the slab
This is the single biggest variable we see in Lawrence County. Properties with stable, well-draining rocky or granular soil need 4 inches of compacted gravel base. Properties in Lawrenceburg's residential subdivisions — built on red clay — need 5–6 inches of base and sometimes geotextile fabric to prevent base migration into the clay over time. We probe the subgrade during the site visit and don't guess at base depth.
Thickness and reinforcement spec
What goes on the slab determines how thick it needs to be. A 30x40 storage barn with mostly foot traffic? Four inches is fine. A shop where you'll park a full-size truck and occasionally pull a loaded trailer in? Five inches with a rebar grid is the right call. We've poured slabs that looked like overkill to the homeowner at signing and were clearly right when they started using the building two years later. Get this right the first time.
Site grading
A level, well-drained building pad keeps slab costs in line. If your site has significant grade change or drainage issues that need correcting before we pour, that site work is a separate cost. We evaluate this during the estimate visit and quote it as a clear line item so there's no surprise.
| Scope | Estimated cost (Lawrence / Giles County) |
|---|---|
| 30x40 slab, 4 in, wire mesh, good site | $10,000 – $13,000 |
| 30x40 slab, 4 in, wire mesh, clay subgrade | $11,500 – $15,000 |
| 30x40 slab, 5 in, rebar grid, vehicle use | $13,500 – $18,000 |
| 30x40 slab, 6 in, rebar, heavy equipment | $16,000 – $22,000 |
What we always include on building slabs
On every pole barn or metal building slab we pour, we stub out electrical conduit during the pour — before the concrete is placed. Running conduit after the fact means core drilling through a finished slab, which costs more and is messier than doing it right during the pour. We position the conduit stub-out where you want your electrical panel, typically at the base of the intended panel wall. It adds almost nothing to the slab cost and saves a headache every time.
Permits for a 30x40 slab in Lawrence and Giles County
A concrete slab for an accessory structure in Lawrence County typically requires a building permit as part of the overall building permit — not just a standalone slab permit. The slab is inspected before concrete is placed (to verify base, reinforcement, and forming) and again as part of the foundation inspection for the building permit. We manage the permit and inspection schedule. In our experience, review time in Lawrence County runs 2–4 weeks for a complete application.
Frequently asked questions
How much does a 30x40 concrete slab cost in Tennessee?
In Lawrence and Giles County, a 4-inch slab with wire mesh runs $10,000–$16,000 installed. Five-inch with rebar runs $13,000–$18,000. Site conditions and use determine where you land in that range. Call for an on-site estimate.
How thick should a 30x40 slab be for a pole barn?
Four inches for light storage use. Five inches for parking full-size vehicles. Six inches for regular heavy equipment or tractor access. We spec this based on your actual intended use during the site visit.
Does the slab cost include the building?
No — slab and building shell are separate scopes. The slab alone is $10,000–$16,000. A 30x40 pole barn shell is $28,000–$42,000 additionally. We can quote and coordinate both as a single project.
How long does it take to pour a 30x40 slab?
Site prep is 1–2 days. The pour is one day. Light use after 7 days, heavy vehicles after 28 days. Permit-to-pour timeline is typically 2–4 weeks including permit review.
Should I pour the slab before or after the building?
We prefer to pour before the building is enclosed for concrete truck access. We plan the slab-and-building sequence at the project start. For embedded-post construction, posts go in first, then the slab pours around them.
For a free on-site estimate on your 30x40 slab in Lawrenceburg, Pulaski, or anywhere in the area, call (931) 369-2134 or request a quote. See our concrete services page and our 30x40 building with slab total cost guide.