Car park lining in Hampshire

Two reasons to line in Hampshire

On the chalk, the ground may drain well enough for infiltration, but where a car park sits over a protected aquifer the engineer may keep vehicle runoff out of it. Lining the sub-base turns the permeable paving into a sealed store, releasing water to the drainage through a controlled outlet.

On the clays and made ground around Southampton, Portsmouth and the Solent towns the reason is simpler: the water has nowhere to soak to. With a liner beneath it, the stone under the parking bays becomes shallow storage, which saves space on plots that have little of it.

Sites that use it

Lined car parks turn up where large areas of hard standing meet a surface-water condition: retail parks and supermarkets, business parks at Basingstoke, Eastleigh and Whiteley, distribution yards along the motorway corridors, hospital and school car parks, and the parking courts on larger housing schemes.

How the lining goes in

Your groundworker excavates the car park and trims it to the falls on the drawing. Before we lay anything we walk it: level, clear of sharp stones and flints, and draining towards the outlets. A protective fleece covers the dig and climbs its walls, and the membrane follows in panels, each heat-welded to the next where it lies. Tape is never used.

Every outlet and overflow, and any duct passing through, is sealed into the membrane, and the perimeter is lifted to the height the engineer drew. A second fleece goes on top to shield the sheet from the stone. Once our test weld and weld log are handed over, the sub-base and blocks are your contractor's to lay.

• Formation inspection before we lay
• Protection fleece under and over the membrane
• Heat-welded LLDPE, HDPE or PP liner
• Outlets and penetrations sealed to the drainage design

Working with crates

Some Hampshire car parks need more storage than a layer of stone can give. The extra usually comes from geocellular crates set into the dig below part of the paving, and since we build those too, one crew delivers the whole buried system under one set of records.