An 18×30 concrete slab covers 540 square feet and typically costs about $2,700-$8,100 installed, with a middle-of-the-market estimate near $4,600. Thickness, reinforcement, excavation, access for concrete trucks, and local labor rates determine where a project lands in that range.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Installed 18×30 slab | $2,700 | $4,600 | $8,100 | 540 sq ft; standard ground-level pour |
| Installed price per sq ft | $5 | $8.50 | $15 | Higher rates reflect added prep or finish |
| Concrete at 4 inches | 6.7 yd³ | 7.5 yd³ | 8 yd³ | Includes a practical allowance for waste |
| Concrete at 6 inches | 10 yd³ | 11 yd³ | 12 yd³ | More material and stronger base may be needed |
What an 18×30 slab usually costs installed
For a straightforward, 4-inch-thick slab with basic broom finishing, a common installed range is $5-$10 per square foot, or $2,700-$5,400 for 540 square feet. A typical estimate around $8.50 per square foot puts the total near $4,590. This assumes a relatively level site, ordinary residential access, standard concrete, and no major drainage or demolition work.
Quotes can reach $10-$15 per square foot, or $5,400-$8,100 total, when the project needs substantial grading, thicker concrete, reinforcement, difficult access, or a more involved finish. A slab intended for a heavy vehicle, workshop equipment, or another concentrated load may need engineered specifications rather than a standard patio-style build.
A useful starting budget is about $4,600 for a basic 18×30 pour, before unusual site work or premium finishes. Assumptions: 540 square feet, ground-level placement, standard concrete, normal access, and typical U.S. residential labor rates.
Where concrete, labor, and base work enter the quote
A contractor’s estimate can combine material, crew labor, equipment, and site preparation into one installed rate. Asking for these items separately helps reveal whether a low bid excludes excavation, reinforcement, or cleanup. A 4-inch slab uses about 6.7 cubic yards before waste; ordering roughly 7.5-8 cubic yards is common after allowing for uneven forms and placement loss.
| Quote component | Typical price | 18×30 estimate | What changes the charge |
|---|---|---|---|
| Ready-mix concrete | $140-$190 per yd³ | $1,050-$1,520 for 7.5-8 yd³ | Mix design, delivery distance, and local supply |
| Labor and finishing | $3-$7 per sq ft | $1,620-$3,780 | Crew size, access, forming, and finish detail |
| Base gravel and compaction | $0.75-$2.50 per sq ft | $405-$1,350 | Base depth and soil condition |
| Reinforcement | $0.50-$2 per sq ft | $270-$1,080 | Wire mesh versus rebar and spacing |
| Forms and equipment | $300-$1,200 per job | $300-$1,200 | Pump, access, edge layout, and rental needs |
These component ranges are not meant to be added at their maximums: contractor bids may bundle labor, base preparation, equipment, and overhead, and local prices vary. Short-load charges can also raise the effective cost per cubic yard when a small delivery does not meet the supplier’s minimum.
Confirm whether the quote includes the compacted base, steel, delivery, forming, cleanup, and any concrete pump fee. If sales tax applies locally, the estimate should show whether it is included.
Thickness, rebar, and soil conditions change the slab price
Thickness has a direct effect on both concrete volume and structural performance. At 4 inches, the slab itself requires about 6.7 cubic yards; at 5 inches, about 8.3 cubic yards; and at 6 inches, about 10 cubic yards, all before waste. A move from 4 to 6 inches can add roughly $500-$1,300 in concrete and related placement costs, depending on mix and local delivery charges.
Reinforcement can add roughly $0.50-$2 per square foot, or $270-$1,080 for this footprint. Welded wire mesh is often less expensive than a rebar grid, while thicker bars or tighter spacing raise material and installation costs. Reinforcement helps manage cracking but does not prevent all cracks; joint placement, subgrade preparation, and curing also matter.
Soil and drainage can create larger price changes than the concrete itself. Removing soft or organic soil, correcting a slope, or building a deeper compacted gravel base can add $500-$2,500 or more. A site that needs more than about 4-6 inches of cut or fill, retaining work, or extensive drainage should be priced after inspection rather than assumed to fit a basic per-square-foot rate.
Specify the intended load and finished slab thickness before comparing bids. A contractor should state the thickness, base depth, reinforcement type, control-joint plan, and concrete strength in writing; vague descriptions make estimates difficult to compare fairly.
Plain broom finish versus decorative concrete prices
A standard broom finish is usually the least expensive practical surface, often included in basic installation pricing. It provides texture for traction and suits many patios, utility pads, and shed slabs. A smooth trowel finish may be appropriate for some interior or covered applications, but finish choice should match exposure and intended use rather than price alone.
Color, stamping, exposed aggregate, or custom patterns can raise an 18×30 project by roughly $1,000-$4,000, depending on design and local labor. Stamping commonly adds about $5-$12 per square foot over a plain finish, while integral color or surface coloring can add around $1-$4 per square foot. These are add-on estimates; some contractors quote decorative concrete as a complete installed rate instead.
Edges and joints also affect the appearance and quote. A simple square form is generally less expensive than curved borders, multiple elevations, steps, or a complex pattern. Sealing may cost an additional $0.75-$2 per square foot, or about $405-$1,080 for 540 square feet, depending on product and preparation.
Choosing a plain broom finish can save several thousand dollars compared with a stamped design. Confirm whether the estimate includes color, sealer, control joints, and decorative borders, since these may appear as separate line items.
Crew size and pour-day labor for 540 square feet
A typical residential crew may spend one to two days on preparation and forming, followed by a pour and finishing day; the full schedule can extend longer if excavation, base compaction, or weather delays are involved. A three- to five-person crew is common for placing and finishing a slab this size, but crew size varies with access, concrete delivery pace, and finish complexity.
Labor charges may be estimated as part of a package or at roughly $50-$100 per worker-hour in markets where contractors itemize time. For example, 40-70 combined crew hours at $60-$85 per hour implies $2,400-$5,950 in labor before considering how a contractor bundles supervision, overhead, and equipment. This calculation is a comparison aid, not a universal labor quote.
Truck access can save time and money. If a mixer cannot get close to the forms, workers may need wheelbarrows, a conveyor, or a pump. A concrete pump can add roughly $500-$1,500, with higher charges possible for difficult setups or longer placements. Ask whether the pump, standby time, and delivery coordination are included.
Labor is most predictable when site access and pour logistics are settled before the crew is scheduled. A narrow gate, long carry distance, steep slope, or tight delivery window can change both crew hours and equipment needs.
Regional labor rates can shift the 18×30 estimate
Installed prices commonly run below the national middle in lower-cost rural markets and above it in high-cost metropolitan areas. As a planning adjustment, rural or lower-cost regions may be about 10%-20% below a $4,600 midpoint, or roughly $3,700-$4,150 for comparable basic work. Expensive metro areas may be 15%-30% higher, putting similar work around $5,300-$6,000 before unusual site costs.
These percentages are broad comparison ranges, not guaranteed regional rates. Concrete plants, fuel, wage levels, local competition, and the distance from the batch plant all affect delivered prices. A remote site may face a delivery surcharge even where labor rates are modest; a city project may incur higher labor costs and more difficult staging at the same time.
Climate can affect specifications as well as scheduling. Areas with freeze-thaw exposure may require a suitable air-entrained mix and careful drainage; those requirements can increase material costs. Local building practices and the slab’s use also matter, so a region’s average price should not replace a written scope tailored to the site.
Compare at least three local bids using the same thickness, mix, base, reinforcement, and finish specifications. This makes regional price differences more meaningful than comparing headline totals that cover different work.
Extra charges for removal, access, and local permits
Replacing an existing pad adds demolition and disposal that a new-build estimate may not include. Breaking and hauling away old concrete commonly costs about $2-$6 per square foot, or $1,080-$3,240 for 540 square feet. The rate depends on slab thickness, reinforcing steel, truck access, disposal fees, and whether the contractor must protect nearby landscaping or structures.
Delivery and access surcharges can include a short-load fee, fuel charge, or pump rental. These may add $150-$600 for a small or inconvenient delivery, while pumping can cost more when setup is complicated. Confirm the minimum order and whether the quoted volume includes waste; an under-order can require a costly second truck, while over-ordering may incur disposal fees.
Permit requirements vary by city and by the slab’s purpose. A small ground-level patio may not require a permit in some jurisdictions, while a garage floor, foundation, accessory structure, or work involving drainage may trigger permits or inspections. Permit fees can range from about $50-$500 or more, and code-driven engineering or inspection work can add further expense.
Ask the local building department whether the intended use, dimensions, and location require a permit. Also check easements, property-line setbacks, and stormwater rules before forming; corrections after the pour are far more expensive than confirming requirements in advance.
Lower the slab bill by controlling scope before the pour
Keep the footprint and shape simple when the full 18×30 area is not essential. Reducing the slab by 60 square feet could save roughly $300-$900 at $5-$15 per square foot, plus any associated base and finish costs. Avoiding curves, steps, extra corners, and separate elevations can also reduce formwork and labor without changing the concrete’s intended use.
Prepare the site only when it is safe and agreed with the contractor. Clearing loose debris or moving stored items may reduce crew time, but excavation, grading, and compaction should follow the specified plan. Improper DIY base work can lead to settlement, cracking, or disputes about responsibility. Clarify in writing what homeowner preparation is permitted and what must be completed by the installer.
Compare quotes with matching specifications rather than selecting the lowest total. Request line items for excavation, base depth, concrete thickness and strength, reinforcement, finish, joints, delivery, disposal, and warranty. If an existing slab is sound and only has minor surface damage, ask whether a targeted repair is feasible; replacement may be necessary for major settlement, structural failure, or an unsuitable slab design.
Schedule during a period when local contractors and concrete suppliers have availability, and avoid last-minute rush work when possible. Weather may limit pouring, and a contractor should not rush curing or placement to meet an arbitrary date. Premium sealers, decorative colors, and upgraded patterns can be added selectively if they serve a practical need.
The most reliable savings come from a simple design, clear site access, and a complete, comparable written scope. Keep necessary thickness, drainage, and reinforcement requirements intact; cutting those items without regard to use can create repair costs that outweigh the initial discount.