Car park lining in Leeds

Why Leeds car parks get lined

The surface lets water in; the question is where it goes next. Over most of the city the ground under the sub-base is clay or weathered mudstone that won't take it, and on brownfield land it may be ground nobody wants water passing through. In both cases the drainage design lines the sub-base so it acts as storage, releasing water to the beck or sewer at a controlled rate.

On a site with no room for a pond, that is one of the more common ways to meet the 2025 national SuDS standards: the storage sits under the parking bays.

Near the Aire and its becks, groundwater can come up towards the formation in a wet winter. A welded membrane keeps it out of the stored volume as well as keeping the rain in.

Where we line

Supermarkets and retail parks, the park-and-ride sites ringing Leeds, hospital and university parking, and the parking areas on new business parks and housing developments. Logistics sites along the motorways can take lined permeable paving in their staff car parks, even where the HGV areas are drained another way. On a city-centre surface car park the job is often done in halves, so part of the parking stays in use while the other half is lined.

Our part of the build

The dig and the trimming are the groundworker's. When they've finished we look over the formation: grades running to the outlets, nothing sharp poking through, no soft spots.

Fleece goes first, over the whole floor and up the faces of the excavation. Then comes the membrane, LLDPE, HDPE or PP as the specification says, panel by panel, every seam heat-welded and a trial weld tested and logged that day. Outlets, overflows and ducts passing through are sealed, the perimeter is brought up to its design height, and a top layer of fleece goes over everything.

Records and what follows

At handover the weld records come to you. Your groundworker then places the sub-base and paving, ideally soon after, so the liner spends as little time exposed as possible.

Where crates are added under the bays for extra storage, we build those too, and they are recorded alongside the lining. One crew, one set of records and one point of contact for the whole buried system makes life simpler for the site and for whoever signs it off.