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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 concrete slab costs may vary. Here is a closer look at the average cost of pouring a concrete slab for a barndominium or for a concrete patio.

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. To get an estimate of the cost of pouring concrete, you can use a concrete slab calculator to help determine costs.

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?