How to Lay a Patio

Once you’ve decided on your patio’s location, draw a detailed plan to scale on graph paper. Your plan should include relevant measurements and nearby features like your house and fencing.

Planning your slab placement is entirely down to personal preference. You may want uniform rows of patio slabs or prefer a pattern consisting of different sized slabs. If you’re using slabs from various pallets, it’s good to mix them up to disguise any colour variation.

Having planned your patio, ‘dry lay’ the slabs in your preferred design. This is an excellent way to visualise the finished patio and double-check that your measurements are correct. Then take a photo of the layout for future reference.

Allow for the right joint size between each slab. If your patio will be next to your house, its surface needs to sit 150mm below the damp proof course.

Mark your layout on the ground using your wooden pegs and string, then use your square to check the corners are completely accurate.

Before you dig, use a Cable Avoidance Tool to ensure there are no hidden pipes or cables beneath the surface. 

Cut the turf into strips with a lawn edger and remove using a spade. Roll up the turf and save some to fill in gaps between the lawn and the patio.

Now you need to calculate how deeply to dig. The depth will vary depending on how you construct your sub-layer and how thick the patio slabs are. For this project, we’re digging a total depth of 175mm to allow for:

• 100mm of MOT type 1 granular hardcore
• 25mm of Slablayer
• 50mm thick paving slabs

Before adding your hardcore mix, you need to calculate the fall. A fall is a gentle gradient that lets rainwater run off easily. For standard non-textured slabs, aim for a 16mm drop in level per metre.

Hammer in a row of pegs 75-100cm apart across the highest side of your site, making sure the marked line is level with the earth. Use a long piece of timber and a spirit level to ensure the pegs are level across the row. Repeat this process for subsequent rows while maintaining the necessary fall.

Add the hardcore mix to reach the top of the pegs. We’re adding the hardcore in 2 x 50mm layers for extra stability here. Add 50mm of hardcore and rake over, so it’s roughly level. 

Then compact the layer using a wacker plate or a tamper. Repeat this process for the second layer.

Next, add 25mm of Slablayer on top. Use a watering can to gently dampen the Slablayer, then rake the surface so it sits level.

The first paving, called the ‘key slab’, is the most important one you lay. It provides a guide for the others, so it needs to be positioned correctly and sit level. The best starting position is the corner at the highest point of the patio. 

Dampen the underside of the stone, lay it down, and gently tap the surface with your rubber mallet to bed it securely into the Slablayer.

Once the first slab is down, work your way across the space, using wood offcuts as spacers to keep a consistent joint gap between every slab.

Once finished, cover the area with plastic sheeting and leave the Slablayer to dry for 48 hours.

This guide shows how to lay a patio for beginners using the easy-to-use Slablayer. If you have more advanced DIY skills, you can mix your own mortar to secure the slabs.

Basic patio mortar is four parts sand, one part cement. As mortar dries in just a few hours, mix in batches to avoid rushing.

Once you’ve measured the amount of sand and cement needed, it’s time to combine them in a cement mixer. The mortar should be able to hold its shape but be easily mouldable.

To create the mix, start with half a bucket of water. Add half the sand and then mix in all the cement. Then add the remaining sand and any more water if it’s needed.

If you don’t have a cement mixer, you can create your mortar using a tray, combining all three elements. In this case, start with less water, adding more gradually as needed.

Lay the mortar for one slab at a time, applying 60mm onto the base layer. Prepare the patio slab by spraying some water to ensure it adheres to the mortar.

Then follow the steps above to secure the slab. You can apply more mortar if you spot any gaps. Repeat the process for all other slabs.

Pointing is the method of sealing the joints around paving slabs, which helps secure the patio and reduce the risk of movement. This also ensures a tidy and level finish. Here’s the pointing method for small, medium and large joints:

• Small joints. For joints less than 5mm wide, use a soft bristle brush to sweep kiln-dried sand into the joints. Then sweep any excess off the finished patio.
• Medium joints. A dry mortar mix is best for joints 5-10mm wide; use one part sand to one part cement. The addition of cement results in a firmer mixture that will set as it absorbs moisture from the ground. Gradually fill the joints as before and sweep any cement off the slabs to prevent staining. Compress the mixture in the joints and keep adding until the joints are full.
• Large joints: A wet mortar mix is most suitable for joints more than 10mm wide. Mix four parts sand and one part cement in a bucket and add enough water to make the mixture smooth and damp. Work the mortar into the joints using a trowel, compressing and smoothing, then carefully brush off any excess mixture.

You should wait for at least 24 hours before using your new patio, no matter the joint size.

Patios are hard wearing and easy to maintain. Regular brushing and washing will stop algae buildup and keep your outside space looking in top condition. The joints are crucial to your patio’s stability, so look after them by filling in gaps that appear over time and removing any breakthrough weeds.

The easiest way to lay a patio is by using a pre-mixed product like Slablayer. You just need to dig a 175mm foundation, compact a 100mm hardcore sub-base, add the dampened Slablayer, and tap your paving slabs firmly into position with a rubber mallet.

You cannot lay paving slabs directly onto soft grass. You must use a lawn edger to cut away the turf, dig down to a depth of roughly 175mm, and build a sturdy, compacted hardcore foundation first to stop your new patio from sinking.

If you need to cut paving slabs to fit awkward spaces around your garden, an angle grinder fitted with a diamond-tipped masonry blade is the most efficient tool. Always remember to clearly mark your line and score the slab first before making the final cut. And wear your safety goggles, dust mask, and ear defenders at all times.

Paving slabs offer a wide variety of finishes, from budget-friendly concrete to highly durable, algae-resistant porcelain. Block paving is a brilliant alternative, especially for driveways, as the small interlocking bricks handle heavy vehicle weight perfectly. Laying block paving can sometimes be a slightly more time-consuming process, while large patio slabs cover ground quickly to give you a clean, modern finish.