How Much Does a 30×30 Concrete Slab Cost?

30x30 Concrete Slab Cost - Steel Frame

One of the most important tasks in the construction of a barndominium is building the foundation. If you’ve decided that using a 30×30 concrete slab is the best method to go about building your foundation, you’ll obviously need to price out this crucial phase in the process.

Let’s take a closer look at how to number-crunch for this all-important aspect of your barndo project!

How Much Does a 30×30 Concrete Slab Cost?

The price of a 30×30 concrete slab varies depending on the supplier, but it typically ranges from $4 to $8 per square foot, with a median price of $6. This means that a 900-square-foot barndominium costs somewhere in the region of $5,400.

However, like with many things when building a home, you won’t be able to get a practical budget from a rough estimate, and there are a number of additional factors that will affect the price per slab. The final cost of your concrete slab can shift dramatically based on several things, including…

  • The lumber to be used for your form
  • The use of fiber mesh inside the slabs (or lack thereof!)
  • Whether you’re going to be hiring laborers to lay the concrete or going down a DIY route.

Laying Foundations Using 30×30 Concrete Slabs: Price Breakdown

30x30 Concrete Slab Cost - Laying Foundation
A residential concrete slab foundation with roughed in plumbing and radiant floor heating tubes. The floor heating system can be water or propane.

To give you a basic idea of the cost of your barndo’s foundations, we’ll first look at a price  breakdown for a 30×30 concrete slab by thickness, without the cost of labor factored in:

  • 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, like many people who set out on a self-build project, you’ve found that you’ll need some additional features for your concrete slabs, here’s the approximate pricing for other common costs:

  • 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

The first three items on our list are all things that, while not required, will help to strengthen the concrete’s foundations. For example, when building a two-story barndominium, larger margins will improve the home’s overall structural strength and come highly recommended. While two-foot-deep concrete slab edges can certainly be functional enough on some terrain, the more commonly-used 12-inch borders tend to be much more sturdy and cost roughly $1 per square foot.

Vapor barriers work to keep moisture and condensation from building up beneath the foundation, which can lead to fissures, cracks, and other structural problems. Vapor barriers are recommended for any building that you’re intending to live in, especially if you’re building in a more humid-than-usual environment. This feature will cost about 50 cents per square foot more.

Concrete slabs can be reinforced using wire mesh, which is also known as wire fabric or wire cloth. This method of laying concrete has a benefit over rebar concrete in that it allows for more flexibility when deciding on the precise shape of your concrete foundations, which rebar does not allow for. Wire mesh comes in a variety of materials, including plain, galvanized, and stainless steel, the latter two being particularly rust-resistant.

Though the final item on this list, site preparation, should be completed before you start pouring concrete and is usually treated as a separate stage, there may be some more work required beyond the basics, such as flattening the terrain on your plot or grading the soil where you’re building to check that it’s level. 

Determining the Cost of your 30×30 Concrete Slab

30x30 Concrete Slab Cost - Set Concrete

When figuring out how much a 30×30 concrete slab will cost, your first step should be to decide whether you’ll hire contractors or go the DIY route, cutting out labor costs and only thinking about tools and materials.

The average cost of a 4-inch thick slab of concrete is $2.83 per square foot. Adding a vapor barrier, thicker edges, a wire mesh, or other enhancements will bring it up to around $4.73 per square foot. Taking everything into account, the overall cost of material will range from $2,547 to $4,257, depending on the exact options you settle on.

If you hire a contractor to do the work, you’ll also have to consider labor costs, which can add several dollars to your foundation’s cost per square foot. The cost of laying a four-inch slab with outsourced labor will typically vary between $6 and $8 per square foot, resulting in a total cost between $5,400 and $7,200.

Keep in mind that, as with anything, the price will vary based on where you buy materials and hire personnel, and construction labor costs may be greater in other places.

Wrapping Up…

We hope you find this price guide on 30×30 concrete slabs useful as you plan out and build your barndominium. When you’ve decided on the look you want to have for your home, you can choose the option to design your own floor plan with a software.

For more guidance on building your own barndominium, be sure to check out the great FAQs, state guides, floor plans, financing, and insurance!