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Thick Concrete Slab

How Thick of a Concrete Slab Do I Need?

However, the usual thickness of a concrete slab is around 10 cm. Whatever you plan on doing, your concrete slab should be at least 5 cm thick. That is the bare minimum of a concrete slab thickness. This is the thickness of the concrete slab alone and it doesn’t include the gravel base, if you are using something like that.

Your concrete slab thickness will depend on the type of the slab and its purpose. The thickness is very important for your project because it directly influences the about of cement and concrete that needs to be poured. That, consequently, means more money for the project material.

Get quotes and useful tips from the experienced concreters. They will let you know what is the best way to go about your concreting project and they will give you the best estimates for your budget.

How Deep Does a Concrete Slab Need to Be?

If you don’t need a gravel base for your concrete slab, you need to dig a hole that is enough for your concrete to be in level with the ground or to be a bit above the ground – again, as much as you want it to be.

This means that your hole for the concrete slab should be around 10 cm deep, for the slab of 10 cm that is directly poured on the ground, or for a slab of 5 cm that has a 5 cm deep gravel base. This is how the ground is prepared for the concrete slab with a base.

Let’s look into different types of concreting projects and the thickness of the concrete slabs that is necessary for them.

How Thick Does a Concrete Slab Need to Be for a Shed?

You can probably get away with pouring a 7.5 cm thick concrete slab if you are planning on a light shed with nothing much in it. However, if you want to be on the safe side, go for a 10 cm concrete slab.

You first need to make sure your concrete slab is in the right place. Check your council regulations, because your shed cannot be just anywhere. Once you have that information, mark the soil where you want to dig and prepare the formwork for the concreting.

In that way, you will see if you need to make adjustments if the soil is slated or there are any other complications.

How Thick Should a Garage Slab Be?

Your garage needs to hold a weight of your car, as well as tons of other car-related items that you store in a garage. This means a significant weight, so don’t try to build concrete foundations for a garage that is less than 15 cm thick. This should be enough for a one-car garage.

If you are driving a truck or you want to have a double garage for two smaller cars, the minimal thickness for your concrete slab is 20 cm. If you use your garage for large and loaded trucks, you will also need to seal your concrete and protect it from damage.


Building a garage is more complicated than building a shed and you need to check if you have the permit to do so. You can concrete garage foundations directly on your soil if you have sandy soil that drains well, but if you have clay or something similar, you will need at least 15 cm to 20 cm of gravel for the base.

How Think Should Concrete Be for a Patio?

Your concrete patio is nice and solid if your concrete slab is 15 cm thick. However, you can make a 10 cm thick concrete slab for a patio that won’t be holding much weight. It is all a matter of the concrete slab size, the soil on which you are building your patio and the weight you are planning to put on your patio.

For example, just two chairs and a small table on well-drained soil will easily work with even 7.5 cm. However, if you want to have a stone or concrete benches, tables, BBQ and entire outdoor kitchens, your minimum is 15 cm.

Check the composition of your soil. If your soil is not well-drained, a base for the concrete slab is necessary. It means digging up a hole, placing the formwork around it, filling it with gravel and then pouring your slab over it.

What Is the Best Thickness for a Concrete Driveway?

Your concrete slab for a driveway should be around 10 cm thick. It doesn’t have to have the gravel base, but the soil underneath it needs to be prepared. This means that all big rocks need to be removed and the soil itself needs to be compacted.


If your driveway is about to hold heavy vehicles, you need to make a thicker concrete slab. Make it at least 12 cm and put a sealer of your concrete so it doesn’t get damaged that easily.

Make sure that your driveway has a slope when you build it. This is a requirement because the soil needs to be drained properly.

How Thick Should a Concrete Path Be?

This is one of the easiest concreting projects. Your concrete slab for a path doesn’t have to be more than 7.5 cm thick. It also doesn’t need a gravel base or anything like that. It is advisable to make expansion joints on every 2 m. Also, most pathways don’t have to be drained in any way, because they usually not wide enough to make issues of that kind.

Those are the minimal requirements for a concrete path. In reality, most people opt for a good 10 cm of thickness and a minimal gravel base for added durability and quality of the concrete path.

These are just some of the most common concreting projects that you can have around your house. While some of them are easy DIY projects, other should never be undertaken without the help of an experienced concreter.

Get quotes for all your concreting projects and plan your budget accordingly. In that way, you get the help of a professional concreter for the amount of money you are prepared to pay.

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