Laying a patio

A patio is a paved area for sitting and eating outdoors, usually next to the house. Laying one is within the reach of a competent amateur, but it is heavy work, and the parts that cannot be seen afterwards, the base and the drainage, decide how long it lasts.

Position and size

The spot nearest the back door is convenient but not always the best. Sun at the time of day the patio will be used, shelter from wind, privacy and the view from indoors all bear on the choice, and some gardens are better served by a second small paved area that catches the evening sun. A table and six chairs with room to move around them need a space of roughly 3 metres by 3 metres.

Rules and checks

In England, paving a back garden does not normally need planning permission. Front gardens are different: since October 2008, covering more than five square metres with a surface that does not let water through requires planning permission unless the rainwater is directed to a lawn or border to soak away. Listed buildings, conservation areas and works that raise the ground level significantly can also need consent, and rules differ in Scotland, Wales and Northern Ireland. The local planning authority advises in cases of doubt.

Next to a house, the finished surface is kept at least 150 mm below the damp-proof course so that rain does not splash above it, and air bricks are left uncovered. The position of drains, inspection covers and buried pipes and cables is established before digging.

Materials

• Natural stone: sandstone, limestone, slate and granite, sold sawn for a crisp finish or riven for a rougher one. Colour varies between slabs.
• Porcelain: thin, dense tiles that resist staining and frost; they need a specialist blade to cut and a priming slurry to bond to the mortar bed.
• Concrete slabs: made in many finishes, including imitations of stone.
• Clay pavers and bricks: small units that suit curves and traditional houses.
• Gravel and permeable paving: let rain soak into the ground and avoid the need for drainage.

Reclaimed stone and brick are widely available. For new imported stone, some suppliers belong to schemes that audit working conditions in the quarries.

How a patio is built

1. Marking out: the area is set out with pegs and string, with levels marked to give a fall of about 1 in 80 away from the house so that rain runs off.
2. Excavation: turf and topsoil are removed to a depth that allows for the sub-base, the mortar bed and the slab, typically 150 to 200 mm in total.
3. Sub-base: about 100 mm of crushed stone is spread and compacted in layers with a plate compactor.
4. Bedding: each slab is laid on a full bed of mortar and tapped down to the string line. Laying on separate dabs of mortar leaves voids that collect water and lets slabs rock and crack.
5. Jointing: gaps of around 10 mm between slabs are filled with mortar or a brush-in jointing compound once the bed has set.

The patio is kept free of foot traffic for a day or two and of furniture for longer, depending on the weather.

Drainage

Paving sheds almost all the rain that falls on it. A patio that drains onto a lawn or border disposes of the water where it falls; one that drains towards the house or a neighbour causes damp and disputes. Large areas may need a channel drain leading to a soakaway. Leaving planting pockets, or setting slabs in gravel with gaps between them, reduces runoff and softens the look.

Safety

Cutting stone, concrete and porcelain produces fine silica dust, which causes serious lung disease. Slabs are cut wet, outdoors, with a close-fitting dust mask rated FFP3, and with eye and ear protection. Paving slabs are heavy enough to injure backs and fingers, and large ones are moved by two people.

Hiring a contractor

Many households have the base and laying done professionally. A written quotation that specifies the depth of sub-base, the type of bed and how the surface will drain makes it possible to compare offers, and trade associations for landscapers and paving contractors publish lists of members.