Where is the water supposed to go?
A driveway is a roof laid on the ground. Fifty square metres of paving sheds a serious volume of water in a storm, and every driveway that fails early has a water story behind it — either it went somewhere it should not have, or it stayed where it landed. Two rules cover most of it: it cannot go onto the highway, and it cannot sit in the sub-base.
Not onto the highway
Surface water from private land must not discharge onto the footway or road. A linear channel inside your boundary across the entrance is the standard answer.
Not against the house
Finished levels stay at least 150mm below the damp proof course, with falls running away from the building and a threshold channel where the paving meets a door or garage.
Not into the sub-base
Water trapped in a closed sub-base softens it. Either the build-up is open-graded and designed to hold water, or it is sealed and drained. A muddle of the two is what pumps and rocks.
Somewhere lawful on your land
A soakaway sized by percolation test, an open-graded permeable build-up, or a connection to an existing lawful surface water route. Never a foul drain.
Clay in the vale, chalk on the scarp
Aylesbury sits on the Gault Clay of the vale floor. Clay holds water, moves seasonally as it shrinks and swells, and gives a soakaway very little to work with. Up on the Chilterns scarp the ground turns to chalk, which drains freely but brings its own issues — solution features and soft spots that need finding before a sub-base goes down.
This is why we dig before we price anything unusual. The excavation tells you which drainage strategy is honest, and the sub-base depth follows from what the ground turns out to be, not from what the quote assumed.
Questions people actually ask
Can driveway water drain onto the road?
No. Discharging surface water from private land onto the public highway is not acceptable — it overloads the highway drainage, and in winter it freezes on the footway. Any driveway that slopes towards the road needs a linear channel across the entrance, set inside your boundary, taking the water somewhere on your own land.
What is a soakaway and how big does it need to be?
A soakaway is a stone-filled or crated void in the ground that holds run-off and lets it seep into the subsoil. Its size depends on the area being drained and how fast the ground absorbs water, which is established by a percolation test — digging a pit, filling it and timing the drop. Guessing the size is the reason so many soakaways sit permanently full.
Do soakaways work in Aylesbury clay?
Often poorly. Much of the vale floor is Gault Clay, which drains very slowly, so a soakaway can fill during a storm and still be full days later. On clay we would rather build a permeable driveway with an open-graded stone sub-base that stores the water across the whole area and releases it slowly, or connect to an existing lawful surface water route, than pretend a small soakaway will cope. On the chalk of the Chilterns scarp — towards Wendover and Stoke Mandeville — infiltration is usually much better.
How much fall does a driveway need?
Enough that water always has somewhere to go and never ponds against the house. As a working rule we lay to roughly 1 in 60 to 1 in 80 across paved surfaces, falling away from the building, with levels set at least 150mm below the damp proof course wherever the drive meets a wall.
Why do you put a linear channel at the entrance and the threshold?
Because it is the only reliable way to stop water crossing a boundary. A channel across the vehicle entrance keeps your water off the footway; one across a garage or door threshold keeps it out of the building. It also gives a clean, straight edge that the paving can be cut to, which is why you can spot it on the edge of every job we photograph.
Does a permeable driveway still need drainage?
It needs a designed build-up rather than pipes. Permeable paving works because of the open-graded stone underneath it — that is the tank. If the ground below cannot infiltrate, the tank needs a controlled outlet. Laying permeable blocks over a clay-bound base with no storage is a permeable surface on paper only.