Why drainage decides how long a patio lasts

A patio that looks flat is not flat. The fall is deliberate, and getting it wrong is expensive inside the house.

Falls

Paving is laid with a slight, deliberate slope so water runs off rather than sitting on it. It should always fall away from the building. Water that ponds on a surface works into joints, and in winter freezing and thawing lifts and cracks them.

The damp proof course

Every house has a damp proof course, usually a visible line in the brickwork near the base of the wall, that stops ground moisture rising into the structure. New paving has to finish far enough below it that rain splashing off the surface cannot bridge it. Paving laid too high against a wall is a common and serious mistake, and the damage shows up as damp inside the house, which costs far more to put right than the patio did.

Where levels leave no choice, the usual solution is a drainage channel or a gravel margin along the wall rather than simply building the paving up.

Where the water is going

Water has to end up somewhere legitimate: a border, a soakaway, or a drainage channel connected appropriately. Directing it at a neighbour’s land or into a foul drain is not acceptable. On clay soils a soakaway may not work well and a different approach may be needed.

What to look for in a quote

A quote that mentions falls, existing levels, the damp proof course and where water is going has been written by someone who has looked at the site properly. One that quotes a rate per square metre and nothing else has not.