How to lay a patio
By Tom Drake | 3rd January 2024 | 6 min read
A patio will give you somewhere to relax, entertain and enjoy your garden on those warm summer days. In this guide, we take you through how you can lay your own patio.
How to lay a patio:
- Mark out the patio
- Clear the area
- Lay the sub base
- Mix up mortar
- Lay the first slab
- Lay remaining slabs
- Pointing
1. Mark out the patio
Before you can start work on your patio, you first need to mark out and clear the area where you want to build it.
Use a builders square and string to mark out the size and shape of your patio. If you like, you can do a ‘dry lay’ of your patio slabs first. This involves laying the slabs and your wooden spacers somewhere in your garden so you know what size and shape will work. This is also useful if you want to avoid cutting any paving slabs.
2. Clear the area
Once you have your patio marked out, you need to clear the area ready for your sub-base. If you're removing an existing patio, you’ll need to remove the slabs and possibly hire a demolition hammer to remove existing concrete.
Before excavating, hire a cable avoidance tool to make sure there are no pipes below the area where you want to build your patio. These should be at least 450mm below the surface, but this might not be the case in older properties.
You need to dig deep enough to allow for a 100mm sub base, 50mm of mortar and the thickness of your paving slabs. If you're building your patio next to your property, you also need to make sure the top of the paving slabs are 150mm below the damp proof course line.
3. Lay the sub base
Once you've excavated to the correct depth, you can mark out the height of your sub base using wood stakes. Starting from the highest point of the patio, hit your stake into the ground until the gap from the top of the stake to the ground is the correct sub base height of 100mm.
You can then add further stakes across the sub base to help you keep it at the correct height. You also need to create a fall in the patio so water is able to drain away. The fall should be 25mm for every 1.5m of patio, so take this into account when hammering in your stakes.
Once you've finished marking the heights, you can then add your sub base using a wheelbarrow. Fill the patio with the sub base then use a plate compactor to compact it. Remember to wear safety boots, safety goggles and ear defenders.
Compact the sub base until it's level with your pegs, you may need to add more as you go.
4. Mix up mortar
Next you need to mix up your mortar. For this, you'll need to mix up four parts sharp sand to one part cement, you can measure these quantities in a bucket. Mortar needs to be used within two hours of being made, so only mix up as much as you think you'll need. When handling mortar, always wear safety glasses, gloves and a dust mask.
Although you can mix the mortar by hand, we recommend using a cement mixer for anything other than a small job. Pour a quarter of a bucket of water into your cement mixer along with the cement and half the sand. You can then run the mixer, add the rest of the sand and more water if necessary, making sure the mortar isn't too dry or too runny.
5. Lay the first slab
Lay your first slab at the highest point of your patio, if you're laying it next to a building, start here. This first slab will determine whether the rest of the patio is correct, so take the time to make sure it's in the right place.
Lay around 60mm of mortar in roughly the same size as your paving slab. Before laying the slab, wet the back of it with water and a brush. You can then lower the slab into place. If your paving slabs are particularly heavy, make sure you have some help when lifting.
Use a club hammer to gently tap the paving slab into place. You can place a piece of timber on top of the slab so you're not hitting it directly. Use a trowel to fill in any gaps under the slab so the mortar is completely flush with the slab. Once you're happy, use a spirit level to check the slab is level.
6. Lay remaining slabs
You can now lay the first row of slabs in the direction of the fall. As you lay each slab, use wooden spacers to create a 5-10mm gap between them.
Use a long spirit level to check the levels of the slabs as you go. You want to aim to create a flat surface that gradually slopes downwards.
Once you've finished laying all the slabs, leave the mortar to dry for 48 hours. If bad weather is forecast, cover your new patio with tarpaulin.
7. Pointing between slabs
The last step to finish your patio is pointing, which involves filling in the gaps between your paving slabs.
Mix up one part kiln dried sand with one part cement in a clean bucket. Gently sprinkle this mixture along the joints and brush it in using a soft brush. You can then use a pointing trowel to compress the joints, adding more of the mix until the joints are full.
That concludes our guide to laying a patio. Hopefully, you'll now feel confident starting your own patio job. Take a look at our huge range of paving slabs so you can start planning your own beautiful outdoor space.
