The most common mistake in pricing a slab is grabbing a per-square-foot number online and multiplying it by the footprint. Most contractor-poured slabs land between $4 and $8 per square foot, but thick house foundations run $12 to $18, and the difference comes almost entirely from what the slab has to carry.
A shed pad, a patio, a two-car garage floor and a house foundation can share the same footprint and still be four different jobs. Each one calls for its own thickness, base, steel and edge detail, and those specs, not the concrete itself, are where quotes pull apart. Decide what will sit on the slab first, and the price follows.
Have measurements ready? Plug them into our free concrete slab cost calculator for a quick estimate by size and thickness.
Start with the load: shed, patio, garage, RV pad or house
The typical specs below are common residential practice, not engineering. Your local code, soil and any engineer’s drawings override them. Average project totals come from This Old House’s March 2026 price data and Angi’s slab cost survey.
| What sits on it | Typical spec | Usual price per sq ft | Average project |
|---|---|---|---|
| Shed or hot tub pad | 4 in., gravel base, wire mesh or fiber | About $6 | About $480 for an 80 sq ft pad |
| Patio or walkway | 4 in., gravel base, broom finish | $4 to $8 | About $3,000 |
| Garage floor (cars) | 4 to 6 in., rebar, thickened edges | $5 to $8+ | About $3,500 |
| RV or boat parking pad | 6 in., heavier base and steel | About $6 and up | About $3,840 |
| Mobile home pad | Engineered to the home’s set-up specs | Varies widely; about $14 in Angi’s example | $9,700 to $22,700 |
| House (monolithic slab foundation) | Thickened footings, vapor barrier, rebar, plumbing roughed in | $5 to $8 simple, $12 to $18 thick | About $12,300; up to $36,900 for 2,000 sq ft |
Notice how much the house line spreads. A small, simple monolithic slab in a mild climate can price near patio rates per foot, while a large foundation with deep footings, foam insulation and under-slab plumbing pushes toward $18. That cost belongs to the home build, so it is covered in more depth in our guide to the cost to build a house.
Each extra inch of thickness, in dollars and yards
Thickness is the spec that moves your concrete order the most. Every inch adds about a quarter of a cubic yard per 100 square feet, and a truck charges by the yard. The per-foot averages are from This Old House; the yardage is plain geometry before waste.
| Thickness | Common use | Concrete per 100 sq ft | Average installed price per sq ft |
|---|---|---|---|
| 4 inches | Patios, walks, sheds, light garages | 1.23 cu yd | About $5 |
| 5 inches | Garages with heavier trucks | 1.54 cu yd | Between the 4 and 6 in. figures |
| 6 inches | RV pads, shops, driveways for heavy vehicles | 1.85 cu yd | About $6 |
| 8 to 10 inches | Foundations, heavy equipment | 2.47 to 3.09 cu yd | $8 to $18 |
Going from 4 to 6 inches adds about 50% more concrete but only about 20% to the average installed price, because labor, forming and base work barely change. That is why contractors on garage forums often advise paying for the extra inch or two if a slab will see trucks, a car lift or a workshop full of heavy tools. Cutting thickness to hit a budget saves less than most people expect.
One 20×20 footprint, two very different quotes
Hypothetical example for illustration, built from the published ranges in this article. Not a quote. A homeowner wants 400 square feet of concrete behind the house. Version A is a patio. Version B is a detached two-car garage floor built to a full spec. Both include a 4-inch compacted gravel base (about 7 tons of crushed stone) and roughly 10% extra concrete for waste and uneven grade.
| Line item | A: 4 in. patio | B: 6 in. garage floor |
|---|---|---|
| Ready-mix, delivered ($175 to $195 per yard) | 5.5 yd: $963 to $1,073 | 8 yd: $1,400 to $1,560 |
| Short-load fee ($15 to $17 per yard under 10 yd) | $83 to $94 | $120 to $136 |
| Gravel base, 7 tons plus delivery | $330 to $725 | $330 to $725 |
| Reinforcement | Wire mesh: $80 to $140 | Rebar grid: $800 to $1,200 |
| Thickened perimeter edges | None | $400 to $800 |
| Vapor barrier | None | About $200 |
| Labor: forming, placing, finishing ($2 to $5 per sq ft) | $800 to $2,000 | $800 to $2,000 |
| Estimated total | About $2,250 to $4,030 | About $4,050 to $6,620 |
| Per square foot | $5.60 to $10.10 | $10.10 to $16.55 |
Same footprint, same crew time, and the garage version costs roughly 60% to 80% more. Almost none of that gap is labor. It is 2.5 more yards of concrete, steel that costs ten times the mesh, and the thickened edges a garage wall sits on. Permits, excavation of sod or slope, a pump and any decorative finish would sit on top of both totals.
The patio’s high end also shows why bare “20×20 slab” figures you see online, often $1,600 to $3,200, can feel low. Many of those leave out the base, the short-load charge or both. Ask any contractor whose number seems cheap whether gravel and grading are in it.
The fees a per-foot price can hide
Residential slabs are small orders by ready-mix standards, and small orders pick up charges that a commercial pour never sees. These show up on the plant’s ticket, and a contractor may pass them through separately:
| Charge | Typical 2026 range | When it applies |
|---|---|---|
| Concrete only, before delivery | $125 to $165 per cu yd | Varies by plant, mix strength and region |
| Short-load fee | $15 to $17 per cu yd | Orders under a full 10-yard truck |
| Truck delivery | About $55 to $65, plus fuel on long runs | Per truck |
| Wait time | About $70 to $75 per hour | After roughly 7 minutes per yard of free unloading time |
| Saturday delivery | About $7 to $8 per cu yd | Weekend pours |
| Tow-behind line pump | $150 to $200 per hour plus $2 to $10 per yard | Truck cannot reach the forms, such as a backyard behind a fence |
| Sealing expansion joints | $2 to $4 per linear foot | Where the slab meets the house, walks or another slab |
| Sealer | $1 to $2.50 per sq ft | Optional; common in freeze-thaw and de-icing salt areas |
| Stain or color | $3.50 to $7.50 per sq ft | Decorative patios |
| Exposed aggregate | $7 to $15 per sq ft | Decorative patios and walks |
| Stamped pattern | $10 to $20 per sq ft | Patios and pool decks; multi-color patterns at the top |
Access matters more than people expect. If the truck can back up to the forms, the chute does the work. If it cannot, you are paying for a pump or for a crew to wheelbarrow several tons of wet concrete, and either one can add hundreds of dollars to a small job.
Bags or a truck? The yardage where the math flips
An 80-pound bag of standard concrete mix yields about 0.6 cubic feet, so it takes roughly 45 bags to make one cubic yard. At around $5 to $7 a bag at big-box stores, that yard of concrete costs $225 to $315 in bags, well above the ready-mix rate, before you count the mixing.
- Under about 1 yard: bags usually win. An 8×10 shed pad at 4 inches needs about 27 cubic feet, or 45 to 48 bags with waste: roughly $240 to $340 in mix, plus $50 to $100 in form lumber, mesh and a ton or two of gravel.
- 1 to 3 yards: the gray zone. Some plants accept 1-yard orders; many want residential customers to take at least 3 yards, and short-load fees make small truck orders expensive per yard.
- Over 3 yards: order a truck. Hand-mixing 135 or more bags before the first batch starts to set is not a realistic one-person job.
For small pads, the savings from doing it yourself are thinner than they look. A pro-installed 80 sq ft shed pad averages around $480, and a DIY version with bags and a gravel base runs roughly $300 to $450 in materials alone, before a mixer rental or any tools you do not own. DIY makes more sense when you already have the tools and the time, or when you do only the digging and base and hire a crew to place and finish.
Why two quotes for the same slab can differ by half
A well-known thread on a garage forum shows how wide the gap can get. A homeowner with a 32×44 shop slab spec, including thickened edges, footings, mesh, vapor barrier, gravel and a pump, received a $30,000 quote, then hired a different contractor for the same specs at $12,500 a few weeks later. That was one project, but the pattern is familiar. The usual causes:
- Region. Angi’s data puts average slab pricing near $5.20 to $5.70 per sq ft in Kentucky and $7.70 to $8.50 in California.
- Season and backlog. A crew booked solid through fall prices high, because it can. Late-season and winter pours can also carry cold-weather costs such as blankets and accelerators.
- Unequal specs. One bid includes rebar, base and a vapor barrier; another assumes mesh and existing grade. They are not the same slab.
- Material swings. Ready-mix prices have kept rising in 2026, and proposed US tariffs on Canadian cement and concrete imports reported this summer have some contractors shortening how long they will hold a quoted price.
Get at least three bids, and make every contractor price the same written spec. That single step does more than any haggling to expose a padded number.
The spec sheet to hand every contractor
Write these down before the first site visit and ask each bidder to price them line by line:
- Use and load: patio, shed, cars, pickup trucks, RV, lift, or a structure on top.
- Size and thickness: length, width, inches of concrete, and any thickened edges or footings.
- Mix: compressive strength (3,000 to 4,000 psi is common for homes) and air entrainment in freeze-thaw climates.
- Base: depth of compacted gravel and who removes sod, roots and excess soil.
- Steel: wire mesh, rebar size and spacing, or fiber, and how it will be held up off the ground.
- Moisture: vapor barrier yes or no (yes under anything enclosed).
- Joints and finish: control joint spacing, broom or trowel finish, any sealer.
- Access and fees: pump needed or not, and whether short-load and delivery charges are included.
- Paperwork: permit and inspection, who pulls them, and the written warranty on cracking and settling.
If a garage or house will sit on the slab, your building department may require an inspection before the pour, and some will require engineered drawings. Confirm with your local building office and a licensed contractor before you sign.
Concrete slab questions homeowners ask next
How soon can I walk or drive on a new slab?
Light foot traffic is usually fine after a day or two, and most contractors say passenger cars can park on a residential slab after about seven days. Concrete keeps gaining strength for weeks and reaches its design strength around 28 days, so heavy trucks and RVs should wait that long. Follow your contractor’s guidance for your mix and weather.
Do I need a permit to pour a concrete slab?
It depends on your town and the project. Foundations and garage slabs almost always need one, while a small patio or shed pad may not. Slabs near property lines, in drainage areas or in an HOA can need approval too, so check with your building department before the pour.
Can I pour new concrete over an old slab?
Sometimes. A sound, level slab can take a bonded overlay or a new layer, but it raises the surface, which can cause problems at door thresholds and with drainage. A slab that is badly cracked, heaved or sinking usually needs to come out, because the new concrete will follow the old movement.
Where should control joints go?
A common rule of thumb is to space joints no more than two to three times the slab thickness in inches, measured in feet, so roughly 8 to 12 feet apart for a 4-inch slab. Joints are typically cut about a quarter of the slab’s depth, soon after finishing. They tell the slab where to crack so random cracks are less likely.
Is fiber mesh a substitute for rebar?
Not for structural work. Synthetic fibers help control small shrinkage cracks as the concrete cures, but they do not carry loads the way properly placed rebar does. Angi’s data shows fiber-reinforced mixes pricing around $10 per square foot versus about $7 for rebar-reinforced, and many contractors use fiber in addition to steel rather than instead of it.
Related cost guides
- Concrete slab cost calculator
- Driveway cost: which surface suits your climate
- Cost to build a house, from bare lot to move-in
- Barndominium cost: what the kit leaves out
- New garage door cost, choice by choice
- Dumpster rental prices for tear-out debris
More related guides: Foundation repair cost · Heated driveway cost
Complete guide: Home Improvement Costs in 2027: A Complete Price Guide
Pricing method: per-square-foot, thickness and project averages from This Old House (updated March 2026) and Angi’s concrete slab cost data; concrete, labor and reinforcement ranges from Inch Calculator; delivery, short-load, wait-time and pump fees from Fixr; crushed stone prices from HelloGravel’s 2026 guide; bag yield from Quikrete’s 80 lb product listing. Worked examples are hypothetical estimates, not quotes. Prices vary by region, plant and contractor. Prices were researched in October 2026 for 2027 planning and may change. See our disclaimer.
