Estimating the total cost is one of the first steps for building a barndominium. Before you can obtain financing, you need a complete construction plan with a breakdown of the costs, including the cost of the foundation.
So, how much does a 20×40 concrete slab cost? The average cost per square foot for a concrete slab is $6. However, prices vary across the country and depending on the features that you choose.
Most barndominiums are built with concrete slab foundations. With a 20×40 concrete slab, you end up with 800-square feet per floor.
You may spend $4 to $8 per square foot, resulting in a price range of $3,200 to $6,400.
Cost Breakdown for a 20×40 Concrete Slab
If you build the foundation yourself, you may pay closer to $3,200. If you hire a contractor, expect to pay between $4,800 and $6,400. Labor accounts for close to half the cost of pouring a concrete slab.
Yet, the average cost is based on a standard foundation with the following features:
- Six-inch-thick concrete slab
- 3,000 PSI concrete with crushed stone
- A row of rebar around the inner edges
- Fiber mesh to strengthen the concrete
- Labor to complete the installation process
Pouring a thinner slab or handling the installation yourself reduces the cost of your 20×40-foot concrete slab.
What Affects the Cost of a 20×40 Concrete Slab?
Some of the details that may result in different prices for a concrete slab include:
- Thinner slabs
- Thicker edges
- Wire mesh instead of fiber mesh
- Adding a vapor barrier
- Local prices for material and labor
A six-inch slab of concrete costs $3.57 per square foot while a four-inch slab costs about $2.83, resulting in a difference of $0.74 per square foot.
Many barndominiums are built on four-inch-thick slabs that are reinforced with thicker edges and wire mesh. You may also choose to add a vapor barrier, which helps control moisture and reduces the risk of cracking. These changes may add close to $1.90 per square foot to the total.
Local prices also influence the cost of a 20×40 concrete slab. If you live in the south or southeast, you may pay less for material and labor compared to barndominium owners in the northeastern and west coast states.
Close to $2.50 of the $6 per square foot average goes to labor. In areas with lower wages, the cost of labor may drop.
How Much Does a 20×40 Concrete Slab Cost? – DIY vs Contractor
If you decide to do all the work yourself, the cost of a 20×40-foot concrete slab may cost between $2,264 and $4,376. The base cost is $2.83 per square foot for a four-inch slab or $3.57 for a six-inch slab. Adding a vapor barrier and other features may add $1.90 per square foot, for a high-end estimate of $5.47 per square foot.
Hiring a contractor may cost between $3,200 and $6,400. Doing it yourself can save around $2,000 in labor. However, you need to understand the steps involved in pouring and finishing a concrete slab.
You must first prepare the site and build a wood form. The form includes four sides constructed from 2×6-inch lumber to hold the poured concrete. You then need to add a gravel bed and pour the concrete. However, one of the most challenging tasks is finishing the concrete, which typically involves the use of a manual or powered trowel.
In the end, the concrete foundation is just one of many expenses when building a barndominium. To answer the question, ‘how much does a 20×40 concrete slab cost?’, the average cost of construction for a barndominium is $30 to $80 per square foot. For a 20×40 (800-square foot) barndominium, you can expect to pay between $24,000 and $64,000 in total construction costs.