How much does a 30×40 concrete slab cost? The average cost is $4 to $8 per square foot. The median price is about $6 per square foot. Based on these averages, you may pay $4,800 to $9,600 with a median estimate of $7,200. However, many details influence the cost of a 30×40 concrete slab.
What Does the Typical 30×40 Concrete Slab Include?
The estimate of $4,800 to $9,600 for a 30×40 (1200 square feet) concrete slab is based on a project with the following options:
- Six inches of 3,000 PSI concrete
- A wood form with 2×6-inch lumber
- Fiber mesh inside the concrete
- A row of rebar for reinforcement
- Laborers to complete the slab
Not all concrete slabs include the same features, so the costs can vary significantly. Here is a closer look at the costs involved in installing a 30×40 slab.
How Much Does a 30×40 Concrete Slab Cost?
The following cost breakdown covers some of the most common features of a concrete slab:
- 4-inch slab – $2.83 per square foot
- 5-inch slab – $3.20 per square foot
- 6-inch slab – $3.57 per square foot
If you plan on pouring a four-inch slab instead of a six-inch slab, you can subtract about $0.74 per square foot from the $6 per square foot average. If you plan on pouring a five-inch slab, you may pay about $5.63 per square foot for material and labor.
Other potential costs include:
- Thickened edges – $1 per square foot
- Vapor barrier – $0.50 per square foot
- Wire mesh – $0.40 per square foot
- Site preparation – $0.60 to $1.25 per square foot
Site preparation is completed before you pour the foundation and is typically considered a separate stage. However, before pouring the foundation, additional work may be needed, such as removing tree stumps or grading the soil to make it level. These activities can add up to $1.25 per square foot to the total.
The other options are intended to strengthen the concrete foundation. For example, adding thicker edges improves the structural strength of the concrete and is recommended when building a barndominium. The edges can be poured up to two feet deep. However, 12-inch edges are more common and cost about $1 per square foot.
A vapor barrier helps limit the collection of moisture and condensation under the foundation, which are common causes of cracks and other issues. Adding a vapor barrier adds another $0.50 per square foot.
Wire mesh can be used instead of fiber mesh to further increase the strength of the foundation. The average cost for wire mesh is about $0.40 per square foot.
How to Determine the Cost of Your 30×40 Concrete Slab
To answer the question ‘How Much Does a 30×40 Concrete Slab Cost?’ you should first decide between hiring a contractor and completing the project on your own. For a DIY project, you only need to pay for material.
The average cost is $2.83 per square foot for material for a four-inch-thick slab. Adding a vapor barrier, wire mesh, and thicker edges increases the cost to $4.73 per square foot. Depending on the features that you include, you may pay between $3,396 and $5,676 for the material.
If you decide to hire a contractor, you also need to cover labor, which can add several dollars per square foot. With labor, the average cost for a four-inch slab is between $6 and $8 per square foot, resulting in a price range of $7,200 to $9,600. Keep in mind that these estimates may vary depending on where you live, as material and labor are less expensive in some regions.