Waasland Shopping Center

Client: AEW Europe
Advisors: Tecon (stabiliteit), Arcadis (parkeren en circuleren) 
Contractor: Zolderse Dakwerken 
Surface: 36.000 m²  
Timing:  2017 - 
Budget: 12.000.000 € 
Status: in execution

Technical renovation guidance I Roof parking - Technical advice I Safety coordination

Complete renovation of the rooftop car park of Waasland Shopping Center in Sint-Niklaas

The Waasland Shopping Center was built on the southern edge of the centre of Sint-Niklaas in 1972. In 2004, the complex was expanded considerably to no less than 45,000 m2, with 140 shops, car parking facilities all around, and a rooftop car park. The rooftop car park, comprising a total of 28,000 m2, has been completely renewed. 

Feasibility study

Commissioned by the owner of the shopping centre, Bureau Bouwtechniek researched the technically best, most sustainable and economically feasible roof structure taking into account :

  • the integral sustainability of the structure,  
  • maintenance,  
  • the lifespan,  
  • accessibility  
  • and energy consumption. 

An important part of the study is a thorough examination of the possibilities of the systems available on the market on the basis of the parameters set, their technical properties and available references. 

On the basis of the analysis of the preconditions and the available systems, the parking roof system was determined with which the design process can be continued.


The load-bearing capacity of the envisaged structure only allows for a limited build-up package. A light package consisting of mortar - EPS system, bituminous waterproofing and cast asphalt was previously chosen. Today, the roof suffers from infiltration, penetration and cracking of the cast asphalt.  

The feasibility study also examined the possibility of insulating the roof according to current EPB regulations, with a U-value of 0.24 W/m²K. As the current roof structure was insulated to a limited extent, with a thin roof structure, the raising of the roof package has a major impact on the connections at the level of the driving ramp, access doors and eaves. In function of the stability, the additional weight must be limited. The insulation has to be made of a single layer in order to absorb the horizontal forces.

Taking this complexity into account, a TOTEM analysis was carried out to investigate the environmental impact of the new roof package. Different insulation thicknesses were compared, assuming an inverted roof with XPS insulation, comparing material and energy costs. The U-values of the different structures were adjusted in function of the EPB calculations for the roof, in order to take into account the correction factor for the water infiltration between the insulation panels that is possible with a reversing roof. Based on the different starting points and boundary conditions, it was decided to limit the insulation thickness to 60mm.

Pardak®80 was chosen for the roof package.

Phased work

The renovation will be carried out in 3 phases. In this way, the roof remains available at all times. 

Bureau Bouwtechniek
BB took care of the investigation, supervised the renovation of the roof parking, supervised the execution and is safety coordinator.

BB-team: Wim Rymenants, ing. Freya Michiels, prof. arch. Jan Moens, ir. arch. Robbe Verelst