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How Much Does a 20×20 Concrete Slab Cost? | Pricing Important Factors

How Much Does a 20x20 Concrete Slab Cost?

So, you want to build a 20×20 barndominium or a 20×20 addition to an existing one. How do you get started on the project? First, you need a foundation.

Barndominiums often sit on concrete slab foundations due to the increased strength and lower costs. But how much does a 20×20 concrete slab cost?

You can expect to pay between $1,600 and $3,200 for a 20×20 slab. The estimates are based on the average cost of $4 to $8 per square foot for a concrete slab. Yet, the costs may vary. Here is a closer look at the average cost of pouring a concrete slab for a barndominium.


Overview of the Typical 20×20 Concrete Slab

The cost of pouring a concrete slab may vary depending on the thickness and features you choose. The typical concrete slab comes with the following features:

  • A wood form to hold the concrete as it hardens
  • Fiber meshing inside the concrete for increased strength
  • A row of rebar around the inner perimeter of the slab
  • 3,000 PSI concrete with a depth of six inches
  • A contractor and labor to install the slab foundation

The last two factors are where the costs may vary. If you choose a thinner slab or complete the project yourself, you are likely to spend less.

So How Much Does a 20×20 Concrete Slab Cost?

Thick concrete slab foundation vs thinner slab foundation

Adding a 20×20 (400 square feet) foundation is not the most expensive part of building a barndominium. However, you have a variety of options that may increase or decrease the cost:

  • Thinner slabs
  • Thicker edges
  • Extra material
  • Textured surface

The average cost of a 20×20 concrete slab is based on the average price of a six-inch slab. If you choose a four-inch slab, you may save up to $0.74 per square foot.

The edges of the concrete slab can also be thickened to increase the strength of the foundation. With 12-inch-thick edges, you pay another $1 per square foot.

Extra material is also available to improve the durability of the concrete slab. Two common recommendations for a barndominium foundation include a vapor barrier and wire mesh reinforcement.

Most concrete slabs include a fiber mesh material. Replacing the fiber mesh with wire mesh offers superior structural strength but costs another $0.40 per square foot. The vapor barrier increases protection against condensation and moisture. It costs close to $0.50 per square foot to add a vapor barrier.

What Is the Average Cost of a DIY 20×20 Concrete Slab?

Construction workers pouring concrete foundation

The average cost of hiring someone to pour a 20×20 concrete slab is between $1,600 and $3,200. However, labor accounts for a large portion of the total cost. If you pour the foundation yourself, you can cut labor from your total.

The base cost for material is $3.57 per square foot for a six-inch slab. A four-inch slab, which is more common for a barndominium, costs about $2.83 per square foot. This gives you a price range of $1,132 to $1,428.

You may also choose to add some of the extra features discussed above, such as the vapor barrier, thicker edges, and wire mesh. These features add another $1.90 per square foot to your total ($4.73 to $5.47 per square foot). Depending on the thickness of the slab, you may pay between $1,892 and $2,188.

While a DIY project saves money, it also comes with challenges. You need to ensure that the wood forms are properly erected. You also need to finish the concrete surface using a power trowel. Any mistakes may limit the strength of your foundation and the security of your barndominium. You may pay a little more labor, but your foundation may last longer.

This article only gives us the basic factors that we need to consider to be able to answer- how much does a 20×20 concrete slab cost?

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