Shopping centres face certain unique challenges which have an effect on movement joint selection. Car parks adjoining shopping centres tend to be connected to the main mall, creating a larger structure than a stand-alone multi-storey car park. This makes the structural movement potentially much greater in the building overall.

The car park often involves the use of the roof, which constitutes, in some cases, a huge expanse of surfacing which can be subject to large thermal stresses.

Shopping centre car parks also tend to be the most convenient parking available to the public due to their immediate proximity to malls, often allowing direct access without going outside. For this reason the demographic spread of the car park user tends to be greater, with the facility being used by older people as well as very young children travelling with parents. In such circumstances it is particularly important to avoid trip hazards.

There are often retail space or storage areas directly under the parking decks. Failure of movement joints allowing water ingress in a normal multi-storey car park situation is, at worst, harmful to the structure and inconvenient to the user. In the shopping centre environment, however, it can have more serious implications, involving damage to stock and serious disruption of the retail process.

Poorly designed movement joints may result in remedial works being required on a regular basis. In a normal multi-storey car park situation this might simply lead to loss of parking revenue. However, in the shopping centre environment, as well as the parking revenue, potential drops in footfall have obvious implications to the traders within the centre.

The most likely place to encounter water ingress is through the gaps created in the structure to cater for the movement of the building. Many readers will have experienced such leakage and may have made numerous attempts to repair movement joints which were poorly specified from day one.

As the years have passed, the design of movement joints has developed so that today bespoke products can be tailored to the exact requirements of the client.

Whether in the new build sector or refurbishment situation, there is now no need for movement joints to fail. There is a detail for every situation and every likely contraction and expansion cycle. At USL StructureCare, for example, the range of movement joint options for car parks has been developed over 25 years. While the same robust materials are utilised, the joints have developed to be pedestrian-friendly and aesthetically pleasing. Movement in the car park structure is unlikely to exceed 50mm at the joint locations, and such movement can be easily catered for without fear of failure.

A development in recent years has been the use of cast-in movement joints rather than the old style bolt down detail. This has the effect of reducing the likelihood of a trip hazard developing during the life of the joint.

As well as negating the potential for a public trip hazard, the cast-in joints tend to be more aesthetically pleasing and are also very easy to repair should the neoprene seal which forms the water barrier be damaged in any way.

An example of cast-in joints is the UCP detail promoted by USL StructureCare. This joint has a 15-year track record for the use in multi-storey car parks and as well as the main neoprene seal, the joint also has a secondary membrane for absolute waterproofing integrity in the unlikely event that the main seal becomes damaged.

The product can be used in new build or refurbishment situations and is proving extremely popular with architects (for its aesthetics), quantity surveyors (for its cost effectiveness), engineers (for its technical capabilities) and centre managers - for its efficiency in keeping the water out!

Car park improvements

ACS Multipark has replaced the pay-on-exit system at Dartford's Priory Centre.

The five-storey car park's 415 spaces are now controlled by a pair of Multipark ticketing machines and barriers, and two pay-on-foot pay stations.

Meanwhile the 580-space multi-storey car park serving Quadrant shopping centre in Swansea has been refurbished by Makers Parking, to achieve the Secured Car Park Award. Works included a new Sika car decking system, concrete repairs, wall and stair coatings in the stair cores, new external cladding, improved lighting levels, new facilities for car park staff, coloured coatings over the asphalt on the ground floor, and corrosion inhibitors.

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