Patio installation: the base, the falls and the paving

Excavation and sub-base

The area is dug out to allow for the sub-base, bedding and slab thickness, and soft ground removed. Crushed stone is laid and compacted in layers with a plate compactor. This layer spreads the load and drains water; skimping here is the most common cause of a patio sinking over time.

Falls and the damp course

A patio should fall slightly away from the house so water drains off rather than pooling or running towards the walls. The finished surface next to the house should sit well below the damp proof course. These two checks protect the house as much as the patio.

Bedding and jointing

Most installers lay slabs on a full mortar bed rather than spot dabs, which leave voids where water collects and slabs can rock. Porcelain typically needs a priming slurry on the back to bond properly. Joints are then filled with mortar or a suitable jointing compound.

Paving materials compared

The main options, in general terms:

• Porcelain: consistent, low maintenance, stain resistant, needs careful cutting and bonding.
• Sandstone: natural variation and texture, may need sealing and occasional cleaning.
• Granite and slate: hard wearing natural stone with a more formal look.
• Concrete paving: widest range of styles and budgets, can fade over time.

Linking the patio to the rest of the garden

Consider steps, edging, paths, lighting and drainage channels at the planning stage. If a pergola, outdoor kitchen or garden room may follow, set post positions or ducting in place now so the patio does not need lifting later.

Drainage and permeable surfaces

Where a patio slopes towards a lawn or planting bed, rainwater can usually soak away there. Where it slopes towards a wall or a hard boundary, a drainage channel or soakaway may be needed. Covering a large part of a front garden with hard, non permeable paving can also need planning permission, so permeable options are often chosen for driveways and front gardens.

Getting the levels right at doors matters as much as the base. The finished patio height has to leave a step or a proper threshold detail at each door, and paving should not bridge the damp proof course. Talk through where water will go during the heaviest rain you get, not just an average day.

Edging is the last structural detail. A mortared edge course or a restraint along any open side stops slabs creeping outwards over time, especially where the patio meets soft ground or a lawn that gets mown right up to the paving.

Keeping a patio looking new

Sweep regularly, deal with spills on natural stone quickly, and refill any joints that open up before weeds get established. Porcelain rarely needs more than a wash; sandstone may benefit from a suitable sealer.

Questions we're asked about this