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40×80 Concrete Slab Cost | Pricing Important Factors

A concrete slab is a common choice for the foundation of a barndominium. It is durable, affordable, and easier to prepare compared to a full basement. However, pouring a concrete slab is still a major project.

So, how much does a 40×80 concrete slab cost?

A 40×80-foot (3,200 square foot) concrete slab may cost $12,800 to $25,600. The average price of a concrete slab is $4 to $8 per square foot. At $6 per square foot, a 3,2000 square foot slab may cost about $19,200.

The estimated concrete slab costs vary depending on a variety of details. Let’s break down the costs of pouring a concrete foundation.

40x80 Concrete Slab Cost

What Does the Average 40×80 Concrete Slab Come with?

A concrete slab may cost $4 to $8 per square foot, but the average price of $6 is based on a slab foundation with certain features. Here are the standard features that you can expect with the average concrete foundation:

  • 3,000 PSI concrete with a thickness of six inches
  • Rebar for added around the inner perimeter
  • Fiber mesh reinforcement inside the concrete
  • Lumber for creating a wood form to hold the concrete
  • Contractors and laborers to complete the project

If you choose options that vary from the standard slab, the foundation may become less expensive or more expensive. Here are some of the details that may result in a different price estimate:

  • Choosing a thinner concrete slab
  • Adding materials for extra durability
  • Living in a region with higher or lower costs
  • Additional site prep

The last detail is something that you may not have a lot of control over. Yet, the cost of labor and building materials varies across the country. Some states, particularly in the West and Northeast, come with higher costs. Areas of the Midwest and the South are often less expensive.

Along with the region where you live, you may need to consider site preparation work. If you need to clear vegetation and trees, you may spend more before pouring the foundation.

What Is the Average 40×80 Concrete Slab Cost Based on Thickness?

The thickness of the foundation is one of the biggest factors in determining the cost of a 40×80 concrete slab. The average cost is based on a six-inch-thick slab. Here are the typical costs for materials for slabs of different thicknesses:

  • $2.83 per square foot for a four-inch slab
  • $3.20 per square foot for a five-inch slab
  • $3.57 per square foot for a six-inch slab

A four-inch slab costs about $0.74 less compared to a standard six-inch slab. You may spend about $2,368 less when pouring a four-inch slab instead of a six-inch slab. However, a thinner slab may need extra reinforcement, which leads to the next set of costs.

What Options Are Available for a 40×80 Concrete Slab?

A variety of materials and options are available to increase the strength and durability of your concrete slab. Here are a few of the most common options and the cost per square foot:

  • Thickened edges – $1
  • Vapor barrier – $0.50
  • Wire mesh – $0.40

Adding all three features can increase the cost by about $1.90 per square foot. For a 40×80 concrete slab, you may spend an extra $6,080 on these features.

wax paper vaport barrier

What Is the Average Cost of a DIY 40×80 Concrete Slab?

The $6 per square foot average for a concrete slab includes a contractor and labor. If you complete the project yourself, you may lower your costs by about $2.40 per square foot. To get an estimate of the cost of pouring concrete, you can use a concrete slab calculator to help determine costs.

A 3,200 square foot concrete slab may cost $11,520, based on the average cost of materials for a six-inch concrete slab. Hiring a contractor to complete the same project may cost about $19,200.

Completing the concrete slab on your own can save thousands but requires experience. Hiring a contractor ensures that the concrete is properly prepared and finished, decreasing the risk of problems down the road.