How to Lay a Concrete Patio
Creating a patio area using poured concrete can really transform your outdoor space. Concrete patios are a long-lasting alternative to using patio slabs or paving bricks, with the added bonus that they are easy to keep clean and there aren’t any gaps for pesky weeds to grow through.
Considerations before laying a concrete patio
Planning ahead when laying a concrete patio will help to ensure you create the best possible finish. A concrete or cement patio will last for a long time, which means they are also difficult and time consuming to remove once cured, so it’s worth making sure you do the job properly.
First, ensure you have enough time and space, as well as the right materials, consider the following as part of your plan too:
Size and shape
Plan the size and shape of your patio properly, consulting any planning regulations that might be applicable in your area. Once the admin is sorted, mark out the patio with strings and stakes or spray paint so you can visualise the finished area. Add about 18 inches to the desired length and width of the patio to make sure you have space to work, and for the concrete forms you’ll pour the concrete into.
Once you have decided on the size of your patio you can calculate the materials needed. The minimum thickness for a concrete patio is four inches, or six to eight inches if you’ll need it to support something like a hot tub or gazebo. You’ll need to work out how much readymix concrete you’ll need to order.
Marking out the proposed area for your patio allows you to anticipate any obstacles. Always check the position of any pipework, septic tanks, and other utilities before digging.
If you are pouring a large concrete patio, you might also want to add reinforcing fibres to your mix, we can recommend you think about ordering a readymix concrete delivery.
What you’ll need to lay a concrete Patio
Ensuring you have the materials and tools you need will make the process of laying a concrete patio much more straightforward. The tools and materials you’ll need will depend on your project, but as a rough guide, consider the following:
- String and stakes
- Spray paint
- Gravel/crushed stone for the base
- Wood for concrete forms (2×6 or 2×8)
- Deck screws to build your forms
- Strikeoff board (a long length of wood used to level the poured concrete)
- Concrete mix (bags) or bags of Portland cement and sand to hand mix
You might instead opt to have readymix concrete delivered to you
Don’t forget to work out how much concrete you need for your project.
- Laser level of large spirit level
- Darby or bull float to finish the slab (depending on size)
- Edging tool (if desired)
- Cement mixer (if you are mixing a large amount of concrete yourself)
Preparing the area – Excavating and levelling
Preparing the area before pouring your concrete is vital to ensure a good quality finish. Your concrete patio will be laid on top of the ground, but it is vital to make sure this ground is stable and level. First, remove any turf or weeds, then to allow for the thickness of your slab and foundations, you will need to excavate between six to eight inches of earth.
Once you have reached the required depth, make sure the area is level and compacted. Depending on the type of soil you are working with, you can either do this by hand, or you can use powered machinery. Don’t forget to allow for the depth of your concrete slab plus the depth of your base material.
Preparing the base
Once the area is levelled, add a layer of compacted gravel or crushed stone, usually between four to six inches deep to ensure there is good drainage and a solid foundation for your cement patio.
Installing the forms
Concrete forms are used as a frame to pour your concrete patio into, they will be removed once the concrete has set. Build your forms from either 2×6” or 2×8” wood, making sure the internal dimensions match your patio dimensions. Place the assembled form on top of your compacted base and ensure the frame is level. For drainage you may need to add a very slight slope so that water doesn’t pool on the slab. You may wish to add a releasing agent to the wood to make it easier to remove from the cured slab.
Next, add wooden stakes every 36 inches along the outside of your form to hold it straight and level. Cut the tops off the stakes so they are flush with the top of the form, as you’ll need to be able to move a long piece of wood over the top of the form to finish your concrete slab.
Pouring a concrete slab
Firstly make sure the pour site is ready to receive your delivery.
Dampen the compacted base slightly, then start to pour your concrete carefully in layers. Make sure each layer fills the form right up to the edge, gently pushing it with a square shovel. You might need to pour your concrete patio in sections if it fills a very large area.
You might also want to check out our article on how to lay a concrete shed base.
Striking a concrete patio
Once you have laid your concrete patio, or a section of a larger slab, you’ll need to do what’s called ‘striking off’. Striking off a concrete patio involves moving a straight piece of wood, sometimes called a strikeoff board, across the top of the wooden form to level the surface of the concrete so it is flush with the top of the frame.
Move the board slowly using a sawing motion side to side, making two passes along the length of the slab. It’s often easier if you have a person holding each end of the strikeoff board. You may need to add small additional amounts of concrete if the edges and corners aren’t quite full.
Smoothing a concrete patio surface
Before finishing your concrete patio, make sure you smooth the surface of the slab. To do this, you’ll need either a darby or a bull-float, depending on the size of the slab. This will smooth the surface and reduce any high spots or gaps left after striking off.
Using overlapping strokes, gently run the tool over the surface of the concrete, you might also want to use an edging tool to create a clean edge to the slab.
Curing a concrete patio
Let your concrete patio cure for at least three days before removing the wooden form, it may need longer in cold weather. You should cover the slab with plastic sheeting if it rains or if the weather is particularly warm, this ensures the ratio of water in your mix is maintained and prevents it from curing too quickly, which can cause cracking.
Leave it as long as possible before walking on your concrete patio, ideally at least three or four days. If you will be adding a structure on top, leave it a little longer, possibly up to ten days. The slab will continue curing for up to 28 days before it reaches its full strength.
Other options – Painting a concrete patio
If you want to transform an existing concrete patio, adding some colour can be a great way to spruce things up a bit. With the right preparation and good quality paint, you can create a beautiful, professional finish by painting a concrete patio. Check out our article on how to paint a concrete patio for more information.