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How to lay a patio

Difficulty: Medium

This is a fairly simple project but paving can be heavy so you may need some help. Depending on the size of your patio, the project could take you two to three days.

Before you get started on any of our 'how to' guides, please take a moment to read through our DIY safety tips.

1. Planning your patio

  • Once you've decided where your patio is going, draw a detailed plan to scale on graph paper. Put in all the dimensions of the patio area.
  • Mark permanent fixtures on the plan - the house, walls, fencing and manhole covers. You have to pave around the covers and they can affect the level of the patio. Also mark on trees and large plants.
  • If you don't want to cut slabs, go for a 'chessboard' layout or one of the ranges that come with half-slabs.
  • Staggering paving (like a brickwork finish) or laying a random pattern of different sized blocks usually means you'll have to cut slabs to get a straight border. Seek advice before you cut slabs.
  • The surface of your patio must be at least 150mm below the damp proof course of the house so rain doesn't bounce off and hit the wall above.
  • Your patio must have a gradual slope away from the house to ensure all water drains off. Allow a drop of about 25mm in every 1.5m (fig. 1) or alternatively install a drainage channel.
  • Allow 10mm-30mm between slabs for fettled edge, natural stone or heavily riven slabs. Leave 10mm-15mm for straight edge slabs.
Make a slope on the patio to make sure water drains away from your house. This should be a 25mm drop for every 1500mm of patio.
Figure 1

2. Measuring up

  • Calculate the area of your patio in square metres. Each pack of paving slabs shows the area it covers. Using a single size slab? Then simply divide the area of your patio by the area covered by one pack to see how many packs you need.
  • If you're using different size slabs, the calculation is more complicated and you should ask for advice.

3. Marking out the patio

  • Accurately transfer your plan to the ground with wooden pegs, a builder's square and string.
  • Mark lines on the wooden pegs to show the depth of working - i.e. the finished level of your hardcore, bedding mortar and the surface of the patio slabs.
  • Make sure the marks for the top surface are level with any existing paving and manhole covers (fig. 2).
  • Remember to allow for a gradual slope away from the house when putting in your wooden pegs (fig. 1).
Lines can be drawn on the pegs to indicate the depth for working.
Figure 2

4. Preparing the base

  • Remove any turf, plants or paving and dig down to a depth of about 150mm to allow for the foundations.
  • To lay a solid base for your paving slabs, you first need a layer of hardcore to a depth of about 50mm to 80mm (fig. 3) over the area of your patio.
  • Use a rake to distribute the hardcore, evening out any bumps. You could hire a powered wacker plate to compress the hardcore to give a good solid base.
  • Add a layer of bedding mortar over the compacted hardcore (fig. 3).
Compacted hardcore flattened with a powered wacker plate forms the solid, flat sub-base for the bedding mortar and paving
Figure 3

5. Preparing the bedding mortar

  • Remove any turf, plants or paving and dig down to a depth of about 150mm to allow for the foundations.
  • To lay a solid base for your paving slabs, first put a layer of hardcore to a depth of about 50mm-80mm (fig. 3) over the area of your patio.
  • Distribute the hardcore with a rake, evening out bumps. You could hire a powered wacker plate to compress the hardcore to give a good solid base.
  • Add a layer of bedding mortar over the compacted hardcore (fig. 3).

6. Laying down the paving slabs

  • Before you lay your slabs, check with a builder's square that the string guide lines are square to the house (fig. 4). If not, adjust the guide lines.
  • Lay down the first slab against the house at the corner, checking its alignment with the string guideline. It's important that the first slab is positioned accurately.
  • Gently tap the slab to the correct level with a club hammer. Use a block of wood to protect the slab (fig. 5).
  • Check the alignment of the slab with a spirit level but allow for the slope away from the house.
  • Carry on until you've laid all the paving slabs. Do a final check to make sure they're all level. 
Helpful hint...

Buy all your paving slabs at the same time so you don't get variations in colour and texture.

Before you lay the first slab, use a builder's square to check the string guide lines are square to the house.
Figure 4
Slabs can be gently tapped until they're the correct level.
Figure 5

7. Pointing (filling the gaps between the slabs)

  • Once your slabs are laid, leave the mortar to dry for at least 24 hours before 'pointing' (filling) the gaps between them. This mortar stops your slabs moving and prevents weeds from growing in the gaps.
  • To make up your pointing mortar, use a semi-dry mixture consisting of four parts building sand to one part cement. Make sure the mortar is only just wet - this will prevent shrinkage.
  • Test the mortar by taking a handful and squeezing it. It should stay as a firm wet ball when you open your fingers and not crumble (too dry) or ooze water (too wet). Adjust the consistency by adding water if it's too dry or more sand and cement (pre-mixed to the correct ratio) if it's too wet.
  • Press the mortar into the gaps with the edge of a trowel.
  • Brush off any surplus mortar before it's completely dry with a semi-stiff brush. Finally, wash the slabs with a damp sponge and clean water to remove all traces of cement.

8. Letting the mortar dry out

  • If you're laying your patio in the summer, make sure the mortar doesn't dry out too quickly as it could crumble.
  • In colder weather protect the drying mortar from rain or frost with polythene sheeting.
  • It will be 24 hours or longer before your patio can be used. That will give it time to dry properly.

9. Maintaining your patio

  • If you want to seal the patio to stop water seepage or fading, check the manufacturer's recommendations. Applying a sealant to paving may affect the colour.
  • If the patio freezes, using salt could damage the surface. Instead get rid of snow and ice with a plastic shovel or stiff brush.
  • Every three months it's worth checking for loose or damaged slabs and making sure the pointing is intact.
  • Look for stains such as alcohol, barbecue fat, chewing gum or bird droppings. Give the stains an intensive cleaning treatment (always follow manufacturer's instructions).
Helpful hint...

Have you got a pressure washer? Use it on a low setting for cleaning your patio. Point it at an angle facing away from the slabs. Don't use it too hard or too close to the slabs or you'll damage the surface of your paving.

How to lay a patio

Tools for the job


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