How Much Does a 12×20 Concrete Slab Cost in 2024?

Concrete slabs may be additional building expenses, but they have many uses, and you’ll likely need one for a substantial construction project. A 12×20 or 240 sq. ft. concrete slab is ideal if you need a foundation for your garage or a small workshop. 

Computing the cost of a concrete slab involves many factors like the size and thickness of the target slab. It would be best to consider other factors like the cost of materials such as cement, gravel, and fill. 

This article explains the cost of concrete slabs and how to compute them to prepare your construction budget better. 

What Factors Will Determine the Cost of a 12×20 Concrete Slab?

The cost of a 12×20 concrete slab will depend on several factors. The most obvious factor is size. A 12×20 or 240 square-foot concrete slab is less expensive than a 20×20 concrete slab because it is smaller and requires fewer materials. 

Your location also plays a crucial role in these computations. If you are building in an area with high labor rates, then a 12×20 concrete slab will cost more than in the neighboring state. If you are building a garage or workshop next to your barndominium, this guide will help you understand how much a 12×20 concrete slab foundation will cost. 

How Much Does a 12×20 Concrete Slab Cost?

Here are cost estimates for a 12×20 or 240 square feet concrete slab using several categories. 

Thickness

The thickness of your concrete slab depends on how you want to use it. A concrete slab foundation should be around 6 inches thick, while a concrete slab walkway can be thinner at about 4 inches. The rule of thumb is to have thicker concrete for load-bearing structures like floors and driveways. 

Thickness	Cost per square foot
4 inches	$5.35
5 inches	$5.80
6 inches	$6.20
8 inches	$7

Inclusions

Although your main concern is building a concrete slab, other incidental costs might be involved. For example, you must clear your land and prepare the site before building a concrete slab foundation for your shouse, garage, shed, or small structure. Below are some common inclusions and their average costs. These figures are on top of the concrete slab cost per square foot:

Inclusion	Cost
Site preparation	$1-$2 per square foot (2)
Wood form	$0.35-$0.38 per square foot (3)

With Additional Features

Although most concrete slabs are made of cement, gravel, and sand, some have other features, depending on where you want to use them. For example, homeowners building pole barn homes in flood-prone areas might want to include vapor barriers in their concrete slabs.

Features	Cost
Vapor barrier	$0.50-$0.70 per square foot (4)
Rebar	$1.40- $1.85 per 2 feet (5)
Wire mesh	$0.28 per square foot (6)

12×20 Concrete Slab Cost Breakdown

Let’s take a closer look at some of the costs associated with making a 12×20 or 240 square feet concrete slab. 

Concrete Bag Cost Estimate

Pre-mixed concrete costs between $4.50 and $27 per bag ⁽⁷⁾. The cost of a bag of pre-mixed concrete differs depending on the type of mixture you need and the size of the concrete bag you are buying. 

Labor Cost Estimate

Installing a concrete slab can cost between $2 and $3 ⁽⁸⁾ per square foot. However, this estimate depends on the prevailing labor rates in your location. Rates can also increase if the site is outside the contractor’s service area. 

Truck Cost Estimate

If you plan on handling concrete installation yourself, you can have wet concrete delivered. This can save you time since you don’t need to mix concrete, especially if you need a large volume of concrete. You can also order wet concrete even if you have a team of builders working for you, as this can lessen their workload and reduce labor expenses. 

Concrete delivery costs an average of $125 to $133 per cubic yard ⁽⁹⁾. These prices cover the materials and delivery costs but do not include installation. Some concrete delivery companies have fuel surcharges if your location is beyond their service area. These charges can range between $20 and $40 per load (7), depending on how far your location is. 

Concrete Removal

If you are pouring concrete at a site with an old concrete slab, you need to have it chipped. This costs you approximately $1 per square foot but can be higher depending on the thickness of the concrete ⁽¹⁰⁾. If you had already included concrete removal cost in your barndominium cost calculation, you don’t need to add it to your concrete slab computation. 

How Do You Calculate the Cost for a 12×20 Concrete Slab?

To give you a better idea of how much it may cost to pour a 12×20 slab, we will use a few different cost averages to provide you with a price range that you can use when budgeting. 

According to this calculator, the estimated concrete volume for a 12×20 concrete slab of 6-inch thickness is 4.444 cubic yards. It is a good idea to add an extra 10% of the size as waste allowance. So, you’d be looking to pour around 4.89 cubic yards of concrete for your slab in total. According to National Ready Mixed Concrete Association, the average cost per cubic yard of concrete in 2022 was $137 ⁽¹¹⁾. So, according to these numbers, you’d have to pay an estimate of $669 just for the concrete. The labor usually costs around $2-$3 per square foot (8), so if we added that, you’d be looking to pay from $1149 to $1389 for your 12×20 concrete slab with labor.

Let’s calculate the estimated price for a 12×20 slab using square footage instead, which in this case equals 240 sq. ft. As we mentioned, the price per square foot of a 6-inch thick concrete slab with labor is around $6.20 per square foot ⁽¹⁾. After doing some basic arithmetics, it turns out that to pour this slab, you’d be looking to pay somewhere around $1636 with an inclusion of a 10% waste allowance.

As you can see, the price range depends on many factors, which differ when using different metrics. To finalize, you should consider budgeting anywhere from $1149 to $1636 for a simple 12×20 concrete slab with labor and no additional features. Make sure to play around with the different concrete slab calculators you can find online, or better yet, simply call a few local concrete companies and ask for quotes in your area.

Should You DIY or Hire a Contractor for Your 12×20 Concrete Slab Project?

A 12×20 concrete slab project is more complicated than it sounds, so it is best to hire a professional, especially if you haven’t poured concrete before. Although going the DIY route can help you minimize expenses, contractors can work faster. Instead of winging it, leave concrete pouring to the professionals and concentrate on other items in your floor plan that you can easily finish. 

Conclusion

Creating a concrete slab is a complicated but necessary part of almost any construction project. A concrete slab flooring can function as your garage, workshop, or shouse’s foundation. You can use it to pave your driveway or walkway. Some homeowners use concrete slabs as roofs. 

Estimating the budget you need for concrete slabs can be tricky. Multiple sources say different things when you search online, which can be confusing. This guide gives you a definitive way of computing the cost of a 12×20 concrete slab to prepare an accurate budget for your next construction project. Make sure you follow our Facebook page for more informative articles about barndominiums, shipping container workshops, shouses, and other unique metal structures. 

References

1. How Much Does A Concrete Slab Cost In 2023? Homeadvisor.
2. Cost Of A Concrete Driveway ConcreteNetwork
3. What Are Common Rebar Prices for Concrete Projects? Angi
4. How to Compare the In-Place Cost of Wire Mesh Versus Synthetic Fibers ABC Polymer Industries
5. How Much Does Crawl Space Encapsulation Cost? Angi 
6. Stamped Concrete Cost For Patios, Driveways & More ConcreteNetwork
7. Concrete Floor Cost – What You’ll Pay For Polished Or Stained Concrete ConcreteNetwork
8. How Much Does Concrete Cost? Angi
9. How Much Does a New Concrete Slab Cost? Angi
10. How Much Does It Cost to Have Concrete Delivered in Your Area? Fixr
11. Ready Mixed Concrete Industry Data Survey. NRMCA