Just the ticket

Car parks represent another market once dominated by concrete that steel is fast making inroads into.

There are more than 4,500 multi-storey car parks in the UK, and demand is increasing all the time. In addition, many of those built during the 1960s and 1970s were poorly designed and constructed, so there is need for these to be replaced or repaired.

"It's a very buoyant market," observes Simon Lamb, divisional manager for specialist car park contractor Makers, a subsidiary of the Keller Group. "The value of the refurbishment market was at least £20m last year, while new build was even higher. Clients, particularly in the public sector, are increasingly regarding car parks as useful cash generators."

Local authorities represent a large chunk of the car park market. As part of their regeneration strategies, many towns and cities are seeking to revitalise their centres as retail hubs, and an important part of that is provision of sufficient parking facilities.

However, both public and private sector clients face two significant problems: car parks are not aesthetically pleasing; and their often foreboding interiors can dissuade some people, particularly single women at night, from using them.

This is where steel comes in. Requiring considerably less material than concrete, it is increasingly being used in car park structures, and in some cases, steel beams are being used to support the concrete-slabbed parking deck areas.

"Compared to traditional, concrete-structured car parks, steel is much lighter in appearance," says Lamb. "It is also less obstructive, and this makes for a much airier interior. Security is also improved, as the whole parking fa‡ade is clearly visible."

Makers recently constructed a £3m new-build car park in Hertfordshire for pharmaceutical giant Amersham plc, and the project illustrates Lamb's points. Makers worked in alliance with architect Hill Cannon Partnership, and Burton-based steelwork contractor Conder Structures, which supplied £600,000 worth of cambered cell beams and associated steelwork for the project.

The client's requirements were key to the Makers-led alliance winning the project in the first place. The outline design brief required a high-density, but user-friendly, car park within a restricted footprint, in keeping with the appearance of surrounding buildings and existing properties.

The alliance successfully bid for the job after proposing a distinct design for the 528-space, three-storey car park; as well as using a steel frame for the structure, steel cambered cell beams would be used for the parking deck areas, instead of concrete.

"It is the first occasion that our cambered cell beams have been used in the construction of a car park," says Conder managing director Gordon Ridley.



Advantages of steel

There are a number of advantages in using the the single cell beams for the parking deck areas.

From a construction viewpoint, time on site was shortened because of the wide use of prefabricated steel. Building a traditional concrete structure in such restricted surroundings, with far more 'wet trades', would almost certainly have taken longer.

"The steel frame system lends itself very well to jobs where site access is restricted because there is so much prefabrication," explains Lamb. "This also gives us greater control over the quality."

The steel structure has also made M&E installation more straightforward, according to Ridley. "Using steel columns in place of other materials allows for easier positioning of ducting and services without the overall strength of the structure being compromised," he says.

It's in the appearance of the finished product though, that the Makers alliance has really scored. The car park is visibly lighter and much more open, not surprising given the reduction in size of the columns: they are 350mm square, as opposed to the 750mm by 350mm size of the concrete columns that would have been used otherwise. The cambered cell beams have also been punctured with holes to provide extra light fill.

Additionally, the exposed external tie beams provide the structure with an aesthetic external appearance often found missing in car parks, and resulting in what Ridley calls "more user appeal" - a key requirement of the client.

One other signficant advantage of the system is that it is demountable. "Should the client want to change the land use on which the car park is sited for whatever reason, then the structure can be dismantled and reassembled somewhere else," explains Lamb. "The concrete slabs of the parking deck areas which rest on the steel beams would not be reusable, but all the prefabricated steel would."

Interestingly, the solution the Makers alliance had originally offered to Amersham was not the cheapest bid presented. It shows to Lamb that clients are bothered less and less about cost and more about quality and appearance.

"I think we will see more and more car parks like Amersham's, as clients see the aesthetic advantages that steel can offer," he says. "This is certainly a product we're going to be pushing more in the future."

He adds that Makers is hoping to tie up a similar deal with Norwich City Council in the first quarter of this year. n