BUILDING A PATIO

Building a patio close to the house is one way of transforming a dull and featureless garden into a durable paved area that’s geared especially for outdoor living. A patio makes a versatile summertime extension to the house, providing space for dining, entertaining, or merely for relaxing and soaking-up the sun. You must plan your patio to take advantage of the best aspect and construct it from materials that are both in keeping with the house and garden and durable enough to withstand harsh weather conditions.

Siting the patio

Patios are usually sited as close to the house as possible – ideally adjoining it – or at least nearby for easy access. The best aspect is south-facing, but whichever way your garden faces, you should examine the proposed site at different times of the day during the summer to see how shadows fall. Neighbouring buildings, or your own house, might obscure the sun and this will severely limit the use of the patio. Unfortunately there’s nothing you can do about this, but if the obstruction is just a tree or tall hedge you might be able to prune it.

Some shadows can be used to your advantage: although you might want to lie sun-bathing at certain times of the day, you’ll appreciate the shade while you eat. If there’s no natural shade, you could attach an awning to the house wall, which can be folded away when not needed. A pergola or trellis on which you can train climbing plants will also provide shade where you need it. Or you might prefer simply to allow enough space for a table with an umbrella or a swing seat with a canopy.

What size patio?

In theory a patio may be as large or small as you wish, but in practice you’ll be limited by available space. Try to relate the dimensions of the patio to the needs – and size – of your household. Measure your garden furniture and allow enough space around it so that you won’t be cramped: the patio must measure at least 2.4m (8ft) from front to back to enable you to position furniture and allow free passage. In general a patio measuring about 3.7m sq (12ft sq) is big enough to take a four-seater table or four loungers. To work out the size and position of the patio make some preliminary sketches of the garden with the proposed patio in various locations. When you’ve decided upon a suitable scheme transfer your ideas to a scale plan on graph paper. Cut out a paper template of the patio and use it in conjunction with the plan to help you decide upon the best position.

What type of surface?

There is a wide range of paving materials available in various shapes, sizes and colours and you should choose those which blend with materials used around the house exterior and garden for a sense of unity. The main requisites are that the surface is reasonably smooth, level and free-draining. Whatever your choice of paving, avoid too great a mix – two types are usually sufficient to add interest without making the surface look cluttered. You can, however, include confined areas of small-scale materials such as cobblestones and granite setts to add a textural change to an otherwise flat scheme composed of larger slabs.

Cobblestones – oval pebbles – can be laid in three ways: on a continuous mortar bed over hardcore foundations; on a bed of dry mortar ‘watered in’ by watering can; or loosely piled on top of each other on compacted earth. Granite setts are durable square-shaped blocks with an uneven surface texture, and can be laid on sand or mortar.

Other small-scale paving materials that can be used in large or small areas include concrete blocks, brick pavers and paving-quality bricks. They’re available in various colours and the blocks also come in a range of interlocking shapes. Lay these materials in patterns for best effect and use coloured mortar joints as a contrast.

You can also use special frost-proof ceramic tiles for a patio surface but they are very expensive and need a perfectly flat base if they are to be laid correctly. Con-sequently, they’re really only suitable for very small patios.

Probably the simplest of surfaces is one made of a solid slab of cast concrete. Although the concrete can be coloured with pigments, many people find its surface appearance unattractive.

Concrete paving slabs are probably the best materials for a simple rectangular patio. Made with reconstituted stone, they’re available in a range of reds, greens, yellows and buff tones with smooth, riven or patterned faces. Square, rectangular, hexagonal and half-hexagonal shapes are also made and they’re easy to lay on a sand bed. Broken concrete slabs, known as crazy paving , can also be used as a patio surface, laid on a mortar bed.

Link the patio to the rest of the garden by building walls, paths and steps in matching or complementary materials.

Marking out patterns

Whatever paving materials you choose you have enormous flexibility in the design of your patio. There’s no reason why, for instance, it should be square or rectangular – most of the materials previously described can be laid in curves or can be cut to fit other shapes and angles. Sketch out some patterns and dry-lay the paving in both width and length to test how the designs work in practice. Adjust the pattern or the dimensions of the patio to minimise the number of cut pieces you use. This will ensure the surface looks ‘balanced’.

Concrete slabs can be laid in various grid and stretcher bond patterns but, for a more informal effect, whole and half slabs can be used together in a random fashion. Crazy paving should be laid with larger, straight-edged pieces at the borders and smaller fragments inside. You can lay bricks in herringbone or basket-weave designs.

Setting the levels

Draw your plan on graph paper, then use it to transfer the shape of the patio onto the site. Use strings stretched between pegs to mark out the perimeter of the patio. You must also drive pegs in to represent the surface level of the patio, so to ensure they’re accurately placed you have to drive a ‘prime datum’ peg into the ground against the house wall (if the patio is to abut the house). The peg should indicate one corner of the patio and should be set in a hole about 300mm (1ft) deep with its top 150mm (6in) below the level of the house damp-proof course. If the soil is spongy you may have to dig deeper in order to obtain a firm enough surface on which to lay the foundations.

Set a second peg in the ground against the wall to mark the other side of the patio, and check that the level corresponds to that of the prime datum peg by holding a long timber straight-edge between the two and checking with a spirit level.

All other marking-out strings and pegs should be taken from the base line formed between these two datum pegs. Indicate squares and rectangles by stretching strings from the two pegs and checking the angle with a builder’s square. Plot out curves by measuring from the base line at intervals and driving in pegs at the perimeter, or use lengths of string or a long hosepipe to mark the curves. Circles and half-circles can be marked out by taking a string from a peg placed as the centre of the circle: you place the first slabs or other paving along the string, then move it around the radius and set the next row.

If size permits, you could incorporate planting areas in your patio by leaving sections un-paved, or simply place tubs of plants on the perimeter.

Laying the paving

When you’ve marked out the shape of your patio, remove the topsoil (which you should save for use elsewhere in the garden) from within your guidelines and set intermediate datum pegs at 1.5m (5ft) intervals over the entire area of the excavation. These pegs have to be sunk to the level of the prime datum peg, using a spirit level on a batten between the pegs. Now is the time to set the drainage fall away from the house.

When you’ve set the levels, fill the hole with hardcore, which you must compact thoroughly by rolling and tamping. Then a layer of sand rolled out flat over the hardcore brings the level of the foundation up to that of the peg tops, and provides a flat base for the paving.

On a site that slopes away from the house you’ll have to build a low retaining wall of bricks or blocks; the ground behind it can be filled with hardcore and then paved. However, where the ground slopes towards the house you must excavate the patio site in the bank (forming a drainage fall away from the house), and build a retaining wall.

PREPARING THE FOUNDATIONS

Patio paving requires foundations of compacted hardcore covered with a blinding layer of sand. The excavation should be:.

– about 150 to 200mm (6 to 8in) deep to allow for 75 to 125mm (3 to 5in) of hardcore plus the sand and paving.

– about 230mm (9in) deep if the patio is to be built up to a house wall, so the paving can be set 150mm (6in) below the dpc.

ALLOWING FOR DRAINAGE

To ensure run-off of rainwater the patio surface must slope by about 25mm in 3m (1 in in 10ft) towards a suitable drainage point, which might be an existing drain or soakaway.

On ground sloping away from the house: construct perimeter walls for the patio from brick, block or stone, to form a ‘stage’. Infill with hardcore and a blinding layer of sand and gravel, then pave. The walls must be set on 100mm (4in) deep concrete footings.

On ground sloping towards the house:

Excavate the site for the patio in the bank, forming a fall away from the house. Build a retaining wall to hold back the earth.

INSPECTION CHAMBERS

The patio must not interfere with access to drainage inspection chambers. If drain covers are within the patio area:.

– build it up to the level of the new surface.

– cover it with loose-laid slabs for access.

TIP: PAVING ROUND TREES

If you’re paving around a tree or shrub to make a garden feature, keep the paving at least 300mm (1 ft) from the trunk to allow rainwater to reach its roots.

There’s no reason why you should settle for a perfectly flat surface when planning your patio – you can create some interesting designs by setting various parts at different levels. As you create these shallow terraces you can build in features such as seating, a barbecue, planters for trees and shrubs, and even a pond. A sunken section gives added interest to even the most plain garden.

Efficient drainage of rainwater is a bit of a problem with a sunken patio because the water will tend to drain into the bottom level, where it can collect. So it’s here that you might need a soakaway. This, in its simplest form, can be a hole about 300mm (1ft) square dug at the lowest point of the garden and filled with rubble; a concrete gutter takes the rainwater from the patio surface to the soakaway. Alternatively, you could leave a sunken patio open-ended at its lowest point so that water drains away into the garden. If the patio is of only one or two levels you could just make a gravel-filled feature area at the lowest point to act as a disguised drain. Access to existing drains mustn’t be blocked with slabs.

When planning, you also have to take note of the problems that might be caused by the garden’s aspect, shade from trees or neighbouring houses, and take account of the recommended minimum sizes for patios. You must also make provision for setting in items such as a rotary clothes line in an area of paving, and leave spaces for trees. You can use the same paving materials for a sunken patio as you could for a single level one, as long as the finished surface is relatively smooth and flat. It’s usually best on larger patios to use large concrete slabs as the main paving material and add feature areas of smaller scale materials such as cobblestones, bricks, granite setts, or concrete pavers. Build up between the levels with bricks or blocks. ,—

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