A 15×20 (300 square feet) concrete slab is relatively small for a barndominium but may be needed for an addition or detached structure. Concrete slabs provide stable footing for frames and cost less compared to other basements or crawlspaces.
How much does a 15×20 concrete slab cost? Based on an average cost of $4 to $8 per square foot, a 15×20 concrete slab cost $1,200 to $2,400. However, those estimates include material, labor, and a six-inch slab.
If you want a more accurate estimate, use the following guide to explore the 15×20 concrete slab cost.
Overview of the Standard 15×20 Slab Foundation
The average prices for pouring a concrete slab are based on a standard slab with the following features:
- Six inches of 3,000 PSI concrete
- Fiber mesh to reinforce the concrete
- Rebar for support
- Wood forms to hold the concrete as it hardens
- Labor to pour and finish the slab foundation
Any variations from the features listed above may alter the price.
Optional Features for a 15×20 Slab Foundation
You have a variety of options when pouring a foundation. Instead of the standard features, you may choose to include one or more of the following options:
- Four-inch-thick concrete slab instead of 6 inches ($2.83 per square foot)
- Vapor barrier to protect against moisture ($0.50 per square foot)
- Edges up to 12-inches-thick ($1 per square foot)
- Reinforced wire mesh for increased strength ($0.40 per square foot)
You can also choose a different thickness for the slab. Many barndominiums are built on top of four-inch-thick foundations, which offers enough support for the heavy metal frame. However, you may want to add thicker edges and wire mesh to help increase the overall strength of the slab. Adding a vapor barrier brings more protection, as it helps eliminate moisture and condensation from under the concrete.
How Much Does a 15×20 Concrete Slab Cost?– An Estimate
To accurately estimate the price range for your 15×20 slab, you need to choose between pouring the foundation yourself and hiring people. DIY projects cost less because you avoid paying for labor. However, you should only pour the foundation yourself if you have experience with these types of projects. Any mistakes may result in costly repairs down the road.
If you choose to pour the foundation yourself, you may pay between $2.83 (four-inch slab) and $3.57 (six-inch slab) for the base material. You may also add some of the features listed above, such as the vapor barrier, thicker edges, and wire mesh, which adds another $1.90 per square foot to the total. This results in a base price of $3.73 for a four-inch slab and $5.47 for a six-inch slab.
If you decide to hire a contractor, a standard six-inch concrete slab costs about $6 per square foot for material and labor. Adding the features discussed brings the total closer to $8 per square foot.
A 15×20-foot slab includes 300 square feet of space. Multiply 576 times the estimated cost per square foot. To get an estimate of the cost of pouring concrete, you can use a concrete slab calculator to help determine costs.
For example, a DIY four-inch slab with no extra features may cost about $1,630 ($2.83 times 576 = $1,630.08). If you hire a contractor and include a vapor barrier and other features, you may pay about $4,608.
Yet, the cost may also vary depending on where you live when you try to add up how much does a 15×20 concrete slab cost? Material and labor cost less in some states, thanks to lower wages and building costs. Oklahoma, Mississippi, Nebraska, Arkansas, and Michigan are the five least expensive states for new construction. Hawaii, California, Washington, Massachusetts, and Alaska are the most expensive states.
If you decide to hire a contractor, you should also obtain quotes from multiple contractors and compare your options to receive the best value.
