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Laying A Patio

Laying a Patio

Adding a patio area to your garden will give you an ‘outdoor room’ to use in good weather. If you have a north-facing garden, place the patio where there is most sun when you are likely to be outside – usually late afternoon. This guide describes how to lay a patio with paving slabs.


  1. Draw a scale plan of your patio. If you’re putting it adjacent to the house, mark the position of drain pipes and manhole covers.
  2. Decide which type of paving slabs you would like. Adjust the size of the patio if you can so that you do not need to cut any slabs – draw them on the plan to see how they fit.
  3. Mark out the ground with string, using marker pegs at each corner.
  4. Tip: Use slabs in plain, light colours to make the space look larger.


  1. Use a spirit level to ensure the pegs are level with the desired level of the finished patio, which must be at least 150mm (6in) lower than the damp proof course.
  2. Do not cover any air bricks – leave an edged ‘hole’ to ensure adequate ventilation.
  3. To allow for a gentle slope away from the house to remove rain water, knock in the pegs 25mm (1in) lower for every 1.5m (1.5yds) width of patio as you move away from the house.
  4. Tip: Use a builder’s square and check the corners are at right angles.

Preparing the area

  1. Excavate about 200mm (8in) of soil extending just beyond the patio boundary. Allow for the thickness of the slabs when calculating depths.
  2. Add a 100mm (4in) layer of hardcore. The hardcore should be firmly compacted – level it with the edge of a board and tamp it down well, or hire a plate vibrator if you have a large area. When compacted, the hardcore should be about 75mm (3in) deep.
  3. Add 50mm (2in) of sharp sand over the hardcore and firm, levelling with a board. The prepped ground should now be at the top of the pegs.

Preparing the slabs

  1. Using a 1:5 cement:sand mortar, start to lay the patio, working towards your pile of slabs.
  2. Put cricket ball-sized lumps of mortar in the corner and the middle for each slab.

Laying the slabs

  1. Carefully place each slab, adjusting the edges to your outline and tap down until level with the appropriate marker peg using a lump hammer and block of wood.
  2. Add 10mm (1/2in) spacers, two to each edge, before laying the next slab, and continue checking each slab against the marker pegs using a straight edge and spirit level to ensure they’re on a gentle slope away from the house.
  3. Continue until all the slabs are laid.


  1. Leave the slabs to dry for a few days then brush a dry mix of 1:3 cement:sand into the cracks.
  2. Run a round-edged piece of wood along the join to compress the mortar slightly below the slab level.
  3. Brush off the surplus, taking care to remove all traces of the mortar. If the slabs are strongly coloured, cement marks will be very noticeable.
  4. Finish off the perimeter with a moist mortar mix, or use edging stones. Allow to dry for a few more days before using your patio.
  5. Tip: For a clean edge, use masking tape on the slab edges and point with moist mortar using a cementing trowel for a clean edge.

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