A concrete slab is a horizontal and flat surface created by pouring concrete. You can use it as a foundation, floor, or roof. A concrete slab will make for an ideal floor if you are building a small barndominium, a storage building, or a workshop.
Because of how versatile a concrete slab is, you will most likely need to build one during a construction project. For this reason, it is important to know how to compute its cost. The cost of a 20×30 concrete slab depends on its size and thickness. The price of building materials, like cement, fill, and gravel, will also be a factor.
In this article, we will help you figure out how to compute the cost of a 20×30 concrete slab. This knowledge will be handy in ensuring you have an accurate budget before making your concrete slab.
Table of Contents
What Factors Determine the Cost of a 20×30 Concrete Slab?
When estimating barndominium costs, you need to consider several factors, like labor costs, cost of materials, etc. This also applies to concrete slabs because the overall cost depends on several factors. The most crucial factor is the size of the slab because the larger the slab is, the more expensive it will be. A 20×30 concrete slab will have an overall area of 600 square feet.
Location is another factor you need to consider. If you live in a place where building materials are expensive, expect your concrete slab to cost more. The best thing to do is spend time canvassing the different suppliers near you. Ask for quotes from these suppliers to compare their prices and buy from the one that offers the best deal.
How Much Does a 20×30 Concrete Slab Cost?
Before we tackle how much a 20×30 concrete slab will cost, let’s take a look at the different factors involved in making one and how each factor influences costing.
Per Thickness
As mentioned, the cost of a concrete slab differs depending on how thick it is. Why does thickness matter in a concrete slab? The thickness of a slab dictates the amount of weight it can support. For example, if you need a simple slab to use as a pathway, you only need a thickness that can support a human’s weight.
However, if the slab will support enormous weights, like those used as flooring for garages or pole barn homes, you need a slab that’s thick enough; hence it won’t crack under heavy weights.
Some concrete slabs also have thick edges. Thicker edges are stronger and can handle heavier loads. These kinds of slabs are best for floors of garages that house heavy vehicles like RVs or heavy machinery.
| Thickness | Cost per square foot |
| 4 inches | $5.35 |
| 5 inches | $5.80 |
| 6 inches | $6.20 |
| 8 inches | $7 |
Inclusions
Making a concrete slab is not just about cement mixes because you will use other items in the process. For example, in making a 600-square-foot concrete slab, you need to use reinforcing bars or rebars. A rebar is needed to help give your slab form. It also helps improve your concrete slab’s tensile strength. In addition, rebars can make a concrete slab more resistant to cracks and breaks.
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Another factor is your mixing equipment. For small jobs, a one-bag cement mixer should be enough. A cement mixer is important because it can help you thoroughly mix your concrete mix to make it strong and durable. A cement mixer can also help shorten the mixing time so you finish your slab quickly. Look for rental companies that rent out cement mixers near you.
If you are building a DIY barndominium, it might be more prudent to include the cost of buying a mixer when computing expenses since it will be cheaper than renting throughout the duration of your build.
| Inclusion | Cost |
| Cement Mixer | Prices start at $439 (2) |
| Concrete Mixer Rental | $97 per day (3) |
| Concrete Rebar | $1.40 – $1.85 per 2 feet (4) |
| Wire Mesh | $0.28 per square foot (5) |
With Additional Features
While most concrete slabs are bare, you need to use a concrete slab with additional features in some instances. Staining a concrete slab floor can make it look attractive if you want to have a concrete slab floor. This is an added feature, so you need to pay for staining on top of the cost of a bare concrete slab.
If your floor plan calls for an outdoor kitchen, you’ll probably want to stamp your floor instead of leaving it bare. Stamping is the process of making a slab look like wood, brick, or tiles. This is a cheaper alternative to installing tiles or bricks for outdoor spaces. It can also help you minimize the amount of money you need to finance your barndominium.
| Features | Cost |
| Vapor barrier | $0.50-$0.70 per square foot (6) |
| Stamped concrete | $9 – $20 per square foot, inclusive of materials (7) |
| Stained concrete | $2 – $4 per square foot, staining only (8) |
20×30 Concrete Slab Cost Breakdown
Now that you know all about concrete slabs and their various components, let’s see how much each component costs.
Concrete Bag Cost Estimate
You cannot make a slab without using concrete mix. This is the most basic and most important slab-making ingredient. The type of mixture you use influences the durability of your concrete slab. A bag of concrete mix costs around $4.50 – $27, depending on the size of the bag and type of mixture you need (9).
Labor Cost Estimate
If you plan on making the concrete slab yourself, you can save a lot on labor costs. However, if you want an expert to make the concrete slab, you need to shell out around $2 – $3 per sq. ft. (10). These are just estimates and can increase depending on your contractor’s qualifications.
Truck Cost Estimate
To save time and ensure that you are using thoroughly-mixed concrete, you can have wet concrete delivered. Wet concrete gets delivered in truck mixers and is ready for pouring, so all you need to do is prepare your formwork for pouring. It costs $125 – $133 per cubic yard to have wet concrete delivered (11). Some concrete delivery companies also have fuel surcharges when delivering to locations outside their service area. Fuel surcharges can be around $20 – $40 per load (9).
How Do You Calculate the Cost for a 20×30 Concrete Slab?
Now that you know all the components and factors that drive the cost of a 600-square-foot concrete slab, let’s check some price cost averages. We will give you some sample computations for a price range to use as you prepare your budget.
To start off, find out how much concrete a 20×30 concrete slab will use. Using this calculator, we now know that a concrete slab that’s 6 inches thick and has an area of 600 square feet needs 11.11 cubic yards of concrete. Then, add 10% to account for wastage, so you need a total of 12.22 cubic yards of concrete mix.
The National Ready Mixed Concrete Association (12) estimates that one cubic yard of concrete costs $137 in 2022. This means that 12.22 cubic yards of concrete costs around $1,674.14.
You can also compute the cost of a concrete slab on a per-square-foot basis. A 20×30 concrete slab equals 600 square feet. We will then multiply this figure by $6.20 (1), which is the cost of a 6-inch thick slab. This means that your concrete slab will cost around $4,092, including the 10% wastage allowance.
Should You DIY or Hire a Contractor for Your 20×30 Concrete Slab Project?
It can be tempting to make your 20×30 concrete slab because of the potential savings you might make. However, this might not be a good idea, especially if you have never made a concrete slab before. Although hiring a contractor is more expensive, an expert can work faster while ensuring that your concrete slab is durable. Knowing that your concrete slab will last longer will be worth the labor costs you need to pay.
Conclusion
A concrete slab is essential to almost any construction project, so it is vital that you know how to compute its cost. Using the information above, you can estimate the costs of slabs depending on their size, inclusions, and extra features.
This will help you come up with an accurate budget to fund the making of your concrete slab. Use our cost guide to ensure you have the upper hand while negotiating with a contractor to build your 20×30 concrete slab. Follow our Facebook page to stay updated on news and articles about barndominiums, prefab homes, shouses, and shipping container homes.
- How Much Does A Concrete Slab Cost In 2023? Homeadvisor.
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- How Much Does Concrete Cost? Angi
- How Much Does a New Concrete Slab Cost? Angi
- How Much Does It Cost to Have Concrete Delivered in Your Area? Fixr
- Ready Mixed Concrete Industry Data Survey. NRMCA
