Paved patio’s in gardens offer a useful and attractive area for eating and relaxing outdoors. Normally a patio is laid right next to the house but this is not always the case and other factors might determine its location. If the bottom of the garden is sunnier for longer periods than the area next to the house you may wish to construct a patio there instead but, if shade is important to you, then at least part of the patio must provide for this.
Start the project by making a scale plan on graph paper, and then make some photocopies of it so you can draw out different ‘arrangements’ within the designated areas. You could pave the area with bricks but it’s quicker and easier to lay larger square or rectangular paving slabs – although due to their size and weight you’ll need a helper to help you lift and move them into place.
1 Marking out the patio
Transfer your plans to the ground using nails, a try square, some strong string and pegs. Measure accurately to ensure adequate space for the slabs – allow up to 10mm (2/5in) between each slab for mortar, and to avoid cutting slabs, choose a chequerboard layout or paving that includes half-slabs.
2 Prepare the site
Start by levelling the site: remove all vegetation and at least some of the topsoil. If your patio will be next to your house, it must slope away from the building to shed rainwater. The ideal ‘fall’ is 1:60 – or 16mm (3/5in) drop in level for every 1m (3ft) distance from the house wall.
3 Ensuring good drainage
With a plate vibrator, compact the excavated ground; if the digging is deep, add a good layer of hardcore. Never reuse topsoil to make up height. If your patio requires a concrete base, see our section on building a garage; otherwise, mortar and slabs can be laid on the compacted surface.
4 Checking depths
Check the depth, level and angle of fall. Your excavations must be deep enough so that the top of the paving slabs will be a minimum of 150mm (6in) below the level of the damp-proof course, allowing for the slab thickness. Never cover or block up an airbrick.
5 Laying paving slabs
If your subsoil is well-compacted, lay a 50mm (2in) layer of sharp sand on top, roll it flat and then lay the slabs directly on this. Alternatively, you can lay a 25mm (1in) compacted layer of sand over a hardcore sub-base and bed the slabs on fist-sized dabs of mortar.
6 Tap slabs into place
Start laying slabs in one corner. Put down five dabs of mortar, one at each corner and one in the middle, then lay the first slab and tap it into place using the handle of a club hammer. Use a spirit level to check that the slab is flat and slopes at the required angle away from the house.
7 Continue laying slabs
Working out from the corner, lay the paving slabs using off-cuts of hardboard as spacers. Leave to settle for a couple of days, then fill the joints with a fairly dry mortar mix. Compact this into the joints and brush off surplus. Leave for 24 hours, protecting from rain and frost.
Cutting a Paving Slab
Before you start cutting paving slabs, make sure you have the correct safety equipment on hand. To cut a slab, first use a straight edge to draw a line in pencil marking the position of the cut on both sides of the slab. Lay two slabs on a flat bed of sand and place the slab to be cut at an angle against them with the cut line on the edge of the top slab. Chisel a groove 2-3mm (1/8 – 1/4in) deep along the line using a bolster and club hammer. Turn the slab over and then repeat the chiselling on the other side. If the groove is chiselled deep enough, the slab will break easily and cleanly after you give it one or two blows along the chiselled groove. You can also put a block above the chiselled line and give that a couple of hammer blows until the slab splits along the line.
If you have a large number of slabs to cut, consider hiring an electric angle grinder with a stone cutting disc to save time and energy. Follow the manufacturer’s instructions carefully and always wear protective eye goggles and stout gloves.
Paving slabs are heavy; the main dangers come from lifting and placing them, so take care not to strain your back, or let them slip through your fingers and drop them on your feet.
Always wear protective goggles, protective gloves and steel-toed caps or sturdy boots when chiselling and cutting paving slabs.