Laying a Patio

Laying paving can be very rewarding. It is a straightforward process, but can be physically demanding, depending on the weight and quantity of your chosen materials. For the best results, take your time. Preparation is the same for flexible paving and fixed paving.

How do I mark out a patio?

Feature areas, such as this floral
pebble design that has been
cemented into a path, add interest
to a paved area.

It is important when making a patio that the edges are straight throughout and that the angles are exact – once made, any inaccuracies are startlingly apparent. Peg out the area with strings stretched between short stakes that have been hammered into the ground. Check the angles with a builder’s square. Do not necessarily aim to align the sides with boundary walls or fences that may themselves not be dead straight. The angles in the patio itself should be true. The strings should be at the height of the 
finished patio to act as a guide when laying the slabs.

How do I ensure the strings are level?

As you hammer in the pegs, check the level by laying a plank or flat piece of wood between two of them. Using a spirit level, keep knocking in the 
pegs until you are satisfied that the line is true.

How do I stop rainwater from puddling on the patio surface?

If the patio adjoins the house, it is good practice to lay it with a gentle slope away from the house, so that rainwater will drain away from the house. A slope of 2.5cm (1in) over 2m (6ft) is adequate for good drainage.

How do I create a slope?

When marking out the site with pegs and strings it is easy to incorporate a slight decline away from the house. Lay a plank between pegs spaced 
1.8m (6ft) apart. Over the second peg, place a chock of wood 2.5cm (1in) thick. Lay a plank between the two pegs and keep knocking in the second one (with the chock) until you achieve a level. Remove the chock. If you then run a string from the top of the first peg to the top of the second, it will show the desired drop of 2.5cm (1in) over a distance of 1.8m (6ft).

The patio is going to adjoin the house. How far below the damp proofing course should it be?

There should be a gap of at least 15cm (6in) between the damp course and the upper surface of the patio.

How deep a foundation should I dig for a patio?

You need to allow a foundation depth of at least 15cm (6in) below the paving slabs. Remember to allow extra for the thickness of the slabs. This depth of foundation is suitable for a patio that sees normal, light foot traffic – a much greater depth would be needed for an area of hard standing for cars and other vehicles. If the ground is soft and peaty, dig a deeper foundation to allow for a 15cm (6in) layer of scalpings.

How do I make the foundation of the patio?

Dig out the site to the appropriate depth. Remove all traces of perennial weeds, especially the roots of woody plants. As a further precaution, put weedkiller on the site. Put down a 10cm (4in) layer of scalpings. 
Tamp this down firmly with your 
feet or with a whacker plate, which can be hired from a tool hire company. Check the level carefully. On top of this, put a 5cm (2in) layer of builder’s sand.

How do I lay fixed paving slabs?

Mortar the slabs in place individually. Starting in one corner, with a bricklayer’s trowel, lay out four strips of mortar to create a ‘box’, slightly smaller than the slab. If the slab is larger than 45cm (18in) across, make a central cross of mortar or place a blob of mortar in the middle. Place the slab in position and firm it down, checking the level as you do so. Carry on laying further slabs in rows.

Should I allow a space between each slab for fixed paving?

Slabs can either be positioned so they butt up against each other tightly or can have a small gap between them. Use spacers about 1cm (1⁄2in) thick laid between the slabs. You can remove the spacer once each slab is 
in position.

Laying Flexible Paving

1: Dig out the area and edge with bricks or blocks, checking the 
level carefully.

Picture of Patio Planting

2: Spread a layer of builder’s sand over a base of scalpings and tamp this down firmly.

Garden Planning

3: Starting at one end, bed the paving blocks directly on to the sand.

Garden Planning

4: Finish by brushing sand over the surface to fill in any gaps.

How do I finish off the patio?

Once you have finished laying the slabs, leave them for a couple of days to allow the mortar to harden. If you have allowed spaces between slabs, brush dry mortar over the patio to fill the gaps. Brush off any excess. Either spray the patio with a light, fine jet of water from a hose or just leave to allow rainfall and moisture in the atmosphere to do the job for you.

Can I cut slabs?

Here a large area of patio is made
visually appealing with the
introduction of a grid of bricks to
break up the expanse of crazy paving.

When designing a patio it is best to choose a size that makes any cutting of slabs unnecessary. But if it is unavoidable, slabs can be cut. Lay a straight edge on the slab where you need to make the cut and score a 
line along it with the edge of a bolster – a special tool for cutting hard materials. Score the underside in the corresponding place. Work along the line with the bolster, hitting it with a club hammer, to deepen the cut. Place the slab over a length of timber, the cut to one side. Tap sharply with the hammer’s handle to split the slab. Special powered cutters can also be hired. It is essential to wear the appropriate safety gear, as flying chips can cause serious eye injuries.

Can I use house bricks for paving an area of land?

Most house bricks are not frost-proof. Bricks laid horizontally absorb moisture which will expand as the weather freezes, splitting the brick. In the garden, engineering bricks (which are frost-proof) should be used.

Where can I find reclaimed paving materials?

Try the gardening press, the small ads in your local paper or the Internet. Visit reclamation yards for antique urns, statues and other one-off pieces.

How do I break up a large expanse of paving?

A large paved area can look blank and uncompromising, though sometimes it can be unavoidable, for instance if you need to link the house with an outbuilding or garage. To break up the space, consider using a combination of different materials. If you are laying square or oblong slabs, replace a few here and there with cobbles set in concrete, or run lines of brickwork through the space in a decorative pattern. You can also create interest 
by incorporating a raised bed or 
water feature.

How do I lay concrete?

Mark out the area as for a patio, then dig out the soil to a depth of 20cm (8in). Prepare a formwork for the area to be concreted by nailing planks to stakes driven into the ground at 1m (3ft) intervals around the perimeter. The top of the planks should be at the level of the top of the proposed concreted surface. Put down a 10cm (4in) layer of scalpings and tamp this down. Pour in sufficient wet concrete to reach the top of the formwork. Work this into the corners, and level it by drawing a beam back and forwards across the top of the form-work. (To concrete a large area, divide it up into strips by creating a form-work about 1m (3ft) wide and no more than 4m (13ft) long. Cast the concrete strip by strip, waiting for the first strip to harden before making the second.)

Laying slabs on mortar

1: Dig out the area to a depth of 20cm (8in), firm the base, and then spread 
a 10cm (4in) layer of scalpings.

Picture of Patio Planting

2: Spread a 5cm (2in) layer of builder’s sand over the scalpings. Tamp this down. Put blobs of mortar on the sand.

Garden Planning

3: Place a slab over the blobs of mortar, manoeuvring it carefully 
into position.

Garden Planning

4: Tamp down the slab. Check the level carefully, and lift it to add more sand or cement if necessary.

Garden Planning

5: You can either lay each slab individually or cover the whole area with builder’s sand first.

Garden Planning

6: Mortar between each slab. Otherwise, simply brush dry mortar into the spaces between the slabs.