How Much Does a Concrete Slab Cost in 2023?

How to Calculate the Cost of Concrete Slab

Concrete slabs usually cost between $4 and $8 per square foot. When you calculate what you’ll need for your project, multiply the length of your project by the width to find the square footage, and add 10% to account for spills and other losses.

As you begin planning, check with your local and state building codes as different projects can have different requirements. For example, there may be thickness and reinforcement requirements that could affect the total price. Remember that while the concrete slab itself may not require a permit, you may need one for the overall project.

Concrete Slab Cost Factors

Next, we’re going to look at the variables that can affect the cost of concrete slabs:

• Labor and equipment

• Thickness

• Base

• Materials

• Finish

Labor and Equipment

Slab flatwork, or pouring the concrete, is messy and complicated work. Each job requires specialized expertise and equipment, from demolition work to prep reinforcement to edging. In general, the labor cost to pour concrete is about $45 per hour, or around $2.50 per square foot. We’ll discuss prices for various concrete projects in a later section.

Thickness

The thicker the concrete slab, the more you should expect to pay, as thicker slabs require more materials and labor. That being said, thicker slabs are stronger and more durable, meaning they’ll last longer.

The average concrete slab is between 4 and 6 inches thick. At 4 inches thick, you’re looking at an average cost of $5.35 per square foot, while at 6 inches thick, you’re looking at $6.20 per square foot. Slabs that are 6 inches are used for residential and commercial building foundations, while 8-inch slabs cost about $7 per square foot and are commonly used on concrete driveways that need to withstand the weight of heavy vehicles. 

Creating thicker edges is also an option to provide reinforcement. For example, concrete poured for a foundation will be thicker around its edges to hold up the walls. A slab with thicker edges, from 2 feet to 12 feet, will cost an additional $1 to $2 per square foot.

Base

In concrete construction, the base is the layer between the soil and the concrete slab to act as a support. Its role is to reduce slab cracking, reduce settlement, and promote drainage. The base is usually a crushed stone material like gravel, but sand can be used in some instances. The climate, soil conditions, and the purpose of the concrete slab will determine whether and what type of base is needed. For a 4-inch aggregate base, expect to pay $65 per cubic square foot. 

Materials

Besides the concrete itself, your project may require additional materials to add reinforcement or control moisture and temperature. 

To help reinforce the structure of concrete slabs that are more than 4 inches thick, you may want to add rebars. On average, the selling price for rebar is between $1.40 and $1.85 per foot of material. Note that this price has been increasing due to nationwide supply shortages. If you're looking for a cheaper alternative, wire mesh is more affordable and is also becoming common for home driveway projects. Both these options will make your concrete slab stronger and help prevent cracks from developing. Wire mesh adds $0.35 per square foot to the cost of your concrete slab.

Styrofoam provides insulation for concrete floors and helps create an energy-efficient space. Since as much as 10% of the heat can be lost through your home's floor, insulating the concrete can save you money on your heating bills. It can also keep water away from the slab. Plan on $0.50 per square foot for Styrofoam insulation.

A vapor barrier is another material that prevents moisture from entering a concrete slab. If your concrete will be in contact with a source of moisture, it can destroy the adhesives in the concrete and lead to swelling, bulging, or cupping. The addition of a vapor barrier will add $0.50 per square foot.

A frustrating cost that surprises most homeowners is a surcharge if your project is in a hard-to-reach area. If you have a narrow fence or blocked pathway, the concrete truck may not be able to reach it. Allot an extra $900 for a mason if this is the case.

Finish

Most people think of concrete and assume it'll be gray, but an assortment of stains, dyes, and other products can transform a slab. Concrete floors can also be finished to resemble tile, slate, or marble or enhanced with decorative stencils, medallions, or even custom graphics. The cost to finish concrete ranges from about $4 to $18 per square foot. It's more per square foot, depending on the finish you select.

Concrete Installation by Application

Your specific project will probably require additional considerations. Below are some factors to consider for common concrete applications, like slab foundations, sheds, garage floors, driveways, and more.

Monolithic Slab Foundation

A monolithic slab foundation costs between $7,000 and $20,000. The term "monolithic" refers to the single pour since a monolithic slab is created by pouring one large area of concrete all at once. Building with a monolithic slab is popular because it's faster and requires less labor than other foundations. Talk to a residential structural engineer near you before making any decisions about using this type of foundation.

Concrete Slab for a Patio 

The cost to install a concrete patio is $3,100 for a new 400-square-foot concrete patio. Stamped concrete can be an attractive option for a patio although it’ll increase the price. If you have an existing patio, it’s possible to pour concrete over an existing concrete patio to increase the size. But beware, if you have cracks or issues caused by frost, they could carry over if you don't resolve them.

Concrete Slab for a Shed

If you're looking to build a shed under the comforting warmth of summertime sun, approach your project with a solid plan. Your shed's foundation and the materials used will depend on the shed size and weight of the items stored inside. You should account for storage weight, but a concrete slab for a shed costs about $480. That's for an 8-by-10-foot space with a 6-inch depth.

Concrete Garage Floor 

It costs about $3,460 for a concrete garage floor for a typical 24-by-24-foot two-car garage with a 6-inch thickness. For extra protection, consider adding an additional sealant. The cost to coat concrete flooring with epoxy ranges from $1,500 to $3,150.

Concrete Driveway

A concrete driveway costs about $3,000, or between $1,800 and $6,000. Expect to pay about $4 to $15 per square foot.

Concrete Parking Pad 

A concrete parking pad costs about $1,200. This is for a 10-by-20-foot parking pad that’s 6 inches thick. You’ll need to check local laws and ordinances before installing a parking pad as they’re not permitted in all cities.

Concrete RV Pad 

A concrete RV pad costs about $3,840 for a typical 16-by-40-foot pad that's 6 inches deep. You may need to tweak the size depending on the length and width of your RV and whether you have slide-outs.

Concrete Slab for a Mobile Home 

A slab for a mobile home costs about $9,720. This is for a 1,330-square-foot mobile home with 6-inch thick concrete.

Types of Concrete

Take a look at the wide array of concrete types you have for your project.

Modern concrete: It's the standard type of concrete for most residential projects, including driveways, patios, and sidewalks. It's a basic mix of cement, aggregate, and water that cures over several days to form a strong foundation. However, your concrete contractor may recommend other types of concrete depending on your project. 

High-strength concrete: It’s appropriate when the structure needs to hold more weight than average, like a multistory house or heavy balcony. Typically, it can hold over 6,000 pounds per square inch (psi).

High-performance concrete: It’s a step above high-strength concrete. It can withstand 8,000 psi and performs well against frequent foul weather.

Ultra high-performance concrete: It can withstand over 17,000 psi without rebar. It's formulated with fibers and extra additives like limestone or quartz flour to make it extremely strong.

Stamped concrete: It’s a concrete that’s “stamped” to create patterns, resembling stone or brick. Stamped concrete costs are typically more expensive because it’s a multistep, time-intensive process. The concrete is poured, colored, stamped, and then left to set. It’ll typically require a sealer to maintain the pattern.

Glass concrete: It uses recycled glass as the aggregate to create visually interesting concrete.

Asphalt concrete: It’s a fast-curing concrete, used mainly in building roads and airports.

Permeable concrete: It allows water to pass through and is used in areas around storm drains.

Self-consolidating concrete: It doesn’t require a cement mixer and is mainly used in restricted and hard-to-reach areas.

Concrete Grade

The strength of concrete will vary depending on its composition, meaning the ratio of cement, sand, and aggregates in the mixture. The more robust and durable the concrete mixture, the more you can expect to pay.

When shopping for concrete, look for the letter M (for Mix), followed by a number. The number will tell you the ratios of cement, sand, and loose aggregate, which will all be mixed with water. For example, concrete labeled "M15" is 1 part cement to 5 parts sand and 10 parts aggregate. Concrete graded between M15 and M25 is appropriate for most residential uses. Concrete graded above M25 is used for commercial construction projects requiring greater strength.

Additional Cost Factors

When planning how to build your concrete slab, you may also want to consider the cost of some common add-on projects. For example, if you increase the square footage of the driveway, your grass may need to be touched up.

Landscaping

Landscape installation costs around $200 per hour. These pros know what to plant where, and they can help you ensure that your trees and flower beds are placed in a way that keeps moisture and roots away from your foundation. They can also advise you on what a lawn needs to avoid water pooling around the foundation. 

Deck or Pergola

If you want to add entertaining space, building a deck costs $7,750 on average. Note that this has become a popular project over the past year. Materials prices have increased from 5% to 10% in 2022 due to demand for building materials. A pergola can be another affordable way to add shade and style to your yard, and building a pergola costs $4,000 on average. Just make sure this project doesn't require a permit.

Firepit

Building an outdoor firepit costs $700 on average. But if you want to cook on your patio, invest in an outdoor kitchen rather than a firepit. The cost to build an outdoor kitchen ranges from $5,550 and $22,500, depending on the size and features you want to include.

DIY vs. Hiring a Concrete Slab Pro

Installing concrete is difficult, even if you're highly experienced with DIY projects. You may save a couple of thousand dollars on labor, but if the end result is a shoddy driveway or an inadequately reinforced floor, you could get yourself into a financial hole trying to fix the problem. Instead, hire a local concrete contractor to take care of this complex work correctly.