The largest indoor shopping mall in the Benelux, Wijnegem Shopping Center, is to be fitted with a new roof with built-in parking facilities. This major renovation project will be designed and implemented by the Dutch specialists at Betonrestore and Zoontjens.
The Wijnegem Shopping Center is located on the eastern edge of Antwerp. The centre, with more than 32,000 m² of shop floor, opened its doors in 1993. Following expansions in 1997 and 2013, the centre, with around 250 shops, now offers 69,000 m² shop floor space. The centre is capped by Europe’s most heavily visited rooftop carpark, where 32,500 m² of rooftop offers 1500 free parking spaces. Every year, the shopping centre receives around 9 million visitors of whom 80% travel by car. Customers prefer to park as close as possible to the entrance, making the rooftop facility the most popular parking area of all.
Extra roof load
After 25 years, the roof is due for renovation. In addition to the high volume of traffic, the vehicles using the rooftop parking tend to be driven fast. This fact, combined with the ever higher average weight of cars (including SUVs) means even more roof load. The aim of the renovation is not only to optimise the rooftop paving but also to increase – in some places to even double – the insulation value.
Reuse of insulation and slabs
The shopping centre has never suffered problems with a leaky roof; a situation the owners wish to maintain. Based on this positive experience, the major renovation project has been outsourced to Betonrestore in combination with Zoontjens and Consolidated, the regular Dutch partners for major renovation work. Within this collaborative venture Betonrestore takes the initiative in terms of new design, whereby a proportion of the old insulation material and slabs will be reused.
10 years roof guarantee
The roof renovation will combine a new mobility plan, which involves a switch to one-way traffic (with a main through route and turnoffs to the parking zones), with energy saving by upgrading the insulation value as well as carrying out all essential roof maintenance on the waterproof finish, and will conclude with the new paving of the entire rooftop carpark area. The combination of Betonrestore, Zoontjens and the roofers at Consolidated, sister company to Betonrestore means that the entire project will be carried out by a single partnership. This combined knowledge and experience will result in a better and more durable roof, including a 10-year guarantee for every aspect of the laying and maintenance of the entire rooftop car parking system.
Waterproofing and parking
The rooftop carpark was laid in 1992 using the Pardak®90 system from Zoontjens. The existing roof structure consists of a series of prefab concrete duct slabs covered with a foam concrete compression layer, a two-layer bituminous roof covering and 40 mm XPS insulation, all capped by the Pardak®90 system. The advantage of this system from Zoontjens is that the two most essential functions – waterproofing and parking – are entirely separate. The possibility for dismantling and reusing the system was and remains a valuable added extra and a useful contribution to the ambitions for sustainability. Following further development, the Pardak®90 system has been upgraded to the Pardak®110 system that offers greater stability under higher traffic load.
Detailed work plan
On the basis of a series of architectural calculations, Betonrestore has drawn up a detailed work plan including structural alterations and optimum reuse of the existing materials. Based on this plan, a design was drawn up for the rooftop carpark and access ramps.
Through route, parking zones and access ramps
To improve stability, the surface will first be graded and levelled. The existing roof covering will undergo intensive cleaning to ensure optimum adhesion, and a complete new top layer will be applied. An extra top layer at expansion joints, edges and areas with very intensive traffic flow, will provide double security. Within this new design, the main through route – a floating floor – will be produced from steel fibre-reinforced concrete. The parking zones will be created using Pardak®110 slabs, while in areas with low traffic intensity, the Pardak®90 slabs will be reused. Part of the old insulation material will also be (stacked and) reused. The access ramps will be finished with a waterproof, reinforced mastic asphalt layer.
Challenge in planning and detail design
The detail design and planning represent the greatest challenges in the renovation plan. All the individual components, including the new access ramps, must be seamlessly connected. At the same time, the intensively used roof carpark must remain in continuous use, whereby the fire access and escape routes must of course be kept open at all times. To make this possible, the renovation work will be carried out in three different phases. Phase one is currently underway. The entire roof will have been completely renovated by October 2018.