Concrete is an essential building block. It’s the foundation of many homes and is the first step in projects such as paving a driveway, adding a deck or patio, or expanding a garage. Even installing a larger, highly-rated air conditioning unit, or building a shed foundation can require putting down concrete to form a stable and properly sealed surface for the new addition.
The cost of concrete depends on the slab’s size and thickness, but you can expect to pay $4–$8 per square foot. We’ve detailed the cost of common concrete slab projects and shared ways to save money.
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What Are Signs That You Need to Replace Concrete?
Most signs that it’s time to pour new concrete are fairly obvious:
- Crumbling or sinking edges
- More than 40 years old
- Poor drainage or pooling water, especially around your home’s foundation
- Substantial cracks, warps, or potholes
What’s the Cost of a Concrete Slab?
A 30-by-30-foot slab of concrete for a driveway, garage floor, or large patio costs $3,600–$7,200 on average. The following factors have the biggest impact on cost.
- Square footage: A greater surface area requires more materials and labor, increasing cost.
- Thickness: Thicker slabs require a higher volume of concrete.
- Project type: Construction projects that require a larger surface area or more stable concrete base cost more.
Cost per Square Foot
Size largely determines the cost of a concrete slab. Here are some common price ranges for various sizes.
Cost by Thickness
A thick concrete slab is more stable but requires more materials and labor to pour. Slabs for most applications need to be 4–6 inches thick, but some projects require thinner or thicker slabs.
| Slab Thickness | Average Price per Square Foot |
|---|---|
| 2 inches | $5.00 |
| 4 inches | $5.00 |
| 6 inches | $6.00 |
| 8 inches | $8.00 |
Many installers price concrete slabs by cubic foot or cubic yard. A cubic yard of concrete—equivalent to 27 cubic feet—will cover an 81-square-foot area with 4-inch-thick concrete and cost $113–$126.
Cost by Type of Project
These common concrete projects can help you estimate your project cost if you’re unsure how large or thick of a slab you need.
| Project | Approximate Cost |
|---|---|
| Car parking pad | $1,200 |
| Driveway | $3,000 |
| Garage | $3,500 |
| Fire pit | $700 |
| Mobile home pad | $9,720 |
| Monolithic slab foundation | $12,300 |
| Patio | $3,000 |
| Pool deck | $8,000 |
| RV parking pad | $3,840 |
| Shed | $480 |
What Factors Affect the Cost of a Concrete Slab?
Slab size and thickness aren’t the only variables that affect cost. Here are some other factors to consider while budgeting.
Concrete Grade
Concrete isn’t a single material; it’s a mixture of cement, water, and an aggregate material such as sand or gravel. The strength of concrete, also called its grade, depends on the ratio of these ingredients and is measured with numbers ranging from M5 to M70. Concrete mix with a grade of M10 to M25 is typically strong enough for residential use and less expensive than higher grades. (Higher numbers are used in large-scale commercial projects).
The word “grade” can also refer to concrete poured over an incline, like for a driveway that goes up a hill. A concrete contractor may charge more if the incline is steep since working with heavy machinery on a slope can be difficult. Your cost will also be higher if the ground grade needs to be increased or lowered before pouring the concrete.
Finish
Concrete is quite versatile. It can be stained, stamped, or sealed to create various appearances, though this will cost more than pouring basic concrete. Stain or dye to change the concrete’s color costs an additional $3.50–$7.50 per square foot. Stamping a design such as tiles or cobblestones into the wet concrete costs $10–$14 per square foot, though more elaborate designs and engraving can cost $18–$20 per square foot. A smooth epoxy finish or a weather-resistant concrete sealer will each add about $4.50 per square foot.
Landscaping Costs
Depending on how much your new concrete slab will change your yard’s layout, you may need to hire a landscaping service to move or replace trees, shrubs, or turf. Many landscapers can also change the incline of the subgrade soil surface if necessary. These services can cost up to $200 per hour for design and implementation.
Reinforcement Materials
Additional materials are usually needed for slabs that hold a great deal of weight, particularly concrete foundations. Wire mesh ($0.35 per square foot) and steel rebar ($2–$3 per square foot) both add strength, particularly when the ground underneath the concrete is poor. Additionally, some home improvement projects require reinforced concrete slabs with thicker edges that can hold more weight. These edges add $1–$2 per square foot. Chemical additives also increase the strength of the concrete mixture itself.
Finally, house foundation costs are higher than other concrete slab projects because most require a 2-inch styrofoam under slab insulation layer at the cost of $0.50– $2 per square foot. Adding a vapor barrier to keep moisture out is also a good idea, which adds about $0.50 per square foot.
Repair vs. Replacement
Concrete is a highly durable material that can expand and contract with changing temperatures, but excessive weight, shifting soil, and obstacles such as tree roots can create cracks over time. It may be possible to repair an existing concrete slab in some cases. For example, a driveway or walkway with cracks or chips in only the top layer can sometimes be resurfaced rather than entirely replaced. Cracks may cost between $500 and $2,500 to repair, and driveway resurfacing can cost anywhere from $1–$10 per square foot.
What Are Common Types of Concrete Slabs?
The type of concrete you choose will depend on your project’s needs.
- Asphalt concrete: This mixture of the two most popular driveway materials is typically used for commercial purposes, such as roads and runways, but it can be used for driveways.
- Cement slabs: It is possible to pour a pure cement slab with no sand or aggregate, but it is more likely to crack and break than a concrete slab.
- Fiber mesh concrete: This mixture includes both large and small metal or polymer fibers that give it additional strength.
- Glass concrete: This concrete uses bits of recycled glass as the aggregate, providing a unique appearance.
- High-performance concrete: Used primarily in commercial applications, this highly weather-resistant formula can support up to 8,000 pounds per square inch (psi) of pressure.
- High-strength concrete: This concrete can support up to 6,000 psi and is used in heavy-duty residential applications.
- Permeable concrete: A more environmentally friendly option, this concrete allows water to pass through, minimizing stormwater runoff, pollution, and erosion. It’s more expensive than regular concrete and doesn’t form as smooth a surface, but it’s just as strong and may prevent drainage issues in your yard.
- Self-consolidating concrete: Regular concrete requires a cement mixer because it will harden if it isn’t kept in motion. Self-consolidating concrete doesn’t need to be constantly agitated after water is added. This makes it a good option if you need to pour concrete in an area inaccessible by a mixer.
- Ultra-high-performance concrete: This mixture is the strongest concrete, supporting up to 17,000 psi without rebar. It’s rarely needed for residential projects.
DIY vs. Professional Concrete Slab Pouring
Pouring concrete may seem like a simple job, but there’s more to it than renting a cement mixer. The ground must be properly prepared, the form must be set up correctly, and the poured concrete must be leveled and sealed. Experienced do-it-yourselfers (DIYers) may be able to take on a small pad for a fire pit, shed, or air conditioner, but anything that supports the weight of a car or house should be professionally installed.
DIY Concrete Slab Pouring
You can save on installation costs by purchasing concrete and pouring it yourself, but you risk creating a slab that isn’t level or durable. On an outdoor project, you may also accidentally direct water runoff toward your foundation.
If the project is small and requires basic, nonspecialty concrete with no extra reinforcements, you may be able to complete the job yourself. Here are the steps you’ll need to take.
- Prepare the ground by clearing, leveling, and compacting the soil that will serve as the subgrade.
- Lay and compact your sub-base material.
- Create a wooden perimeter to serve as your concrete form.
- Lay down wire mesh or rebar on top of the sub-base if necessary.
- Mix your concrete and pour it into the form.
- Flatten the top of the wet concrete with a screening tool.
- Use a floating device to compact the wet concrete.
- Create parallel grooves every 5 to 6 feet to allow the concrete to expand and contract with the weather.
- If you plan to walk on the finished slab, use a broom or other tool to slightly roughen the surface of the concrete to provide traction.
- Seal the concrete and leave it to cure. It can support weight after 48 hours, but it won’t fully cure for up to 28 days.
Professional Concrete Slab Pouring
Though more expensive than doing the job yourself, professional concrete contractors can get the job done quicker and better than most homeowners. They can advise you on the best type of concrete for your project and the reinforcements you’ll need. They’ll prepare the area, pour the concrete, level it, and add any requested finishings. They can also advise you on maintaining and repairing your new concrete slab.
What Is The Life Expectancy of Concrete Slabs?
Most concrete slabs last 30–40 years and can last up to 100 years if properly installed and sealed. How long the concrete lasts depends on what it’s used for and how well it’s maintained. The climate also plays a large role: Although concrete can adapt to changing temperatures, it tends to crack in climates where the ground regularly freezes.
Slabs such as driveways and sidewalks that are subjected to the elements and used frequently have the shortest life spans, but laying foundations can last a lifetime.
What Is the Return on Investment on Concrete Slabs?
There’s not much data about a concrete slab’s return on investment (ROI). However, given concrete’s substantial life span and ability to extend a home’s square footage, it’s likely to be very valuable. A new concrete slab foundation, particularly in a warm climate, will increase your property value substantially. Similarly, outdoor gathering spaces such as decks and patios are in high demand, so creating the groundwork for such a space has a high ROI.
How To Save Money on Concrete Slab Costs
Here are some ways to save on concrete slab costs, even if you hire a professional contractor.
- Do as much prep work yourself as possible, such as moving turf and plants or breaking up and removing the old slab.
- Don’t use more concrete than you need. This means thinking critically about the surface area and slab thickness.
- Don’t use higher-performance concrete than you need, as it costs more.
- Place concrete pads for things such as air conditioners and propane tanks on ground that’s already level and won’t need to be regraded.
- Design slabs with straight lines, as these are less labor-intensive to pour than designs with curves.
- Use subgrade or recycled concrete if your project doesn’t require high-performance or specialty concrete.
- Forgo staining or stamping, which increases cost.
- Get cost estimates from at least three contractors before making your choice.
Seal, clean, and maintain your concrete regularly to ensure it lasts as long as possible.
Our Conclusion
Concrete slabs can be expensive, but they’re often important structural components that must bear a lot of weight, so it’s worth having them poured correctly. This means hiring professional concrete contractors to ensure the slab is level and properly reinforced. These contractors typically offer free estimates for their services, so do some comparison shopping and check online reviews to find the right one for you.
FAQs About Concrete Slabs
Can I pour my own concrete slabs?
You can pour small concrete slabs to support things like an air conditioner condenser unit or fire pit. However, we recommend hiring professionals for larger projects such as concrete floors, foundations, and driveways.
How much does it cost to pour a 20×30 concrete slab?
Concrete costs $4–$8 per square foot on average. This means a 20-by-30 foot concrete slab will cost $2,400–$4,800, depending on the slab’s thickness and the type of concrete needed.
What are other cost factors included in pouring a concrete slab?
Besides the cost of the concrete itself, which can vary by the ingredient ratio, you’ll need to account for the cost of preparing the ground and sealing or changing the concrete’s appearance. You’ll also need to pay for labor from a professional contractor or rent or buy the equipment to do the work yourself.
What is the average cost of a 20×20 slab of concrete?
Concrete costs $4–$8 per square foot on average. This means you’ll pay $1,600–$3,200 for a 20-by-20 foot concrete slab, depending on the slab’s thickness and concrete type.
