Client: Delhaize 
Location: Elsene 
Surface: green roof 200 m² – entrance area 250 m² 
Budget: € 94.500 - € 47.500  
Timing: 2013
Status: realized

Technical renovation support I Roofs & roof parking lots

Bureau Bouwtechniek has been one of the regular partners of Delhaize since 2011, for the execution of study assignments for roofs within the Belux Delhaize Group. On an annual basis, BB assists in roof renovations for about 25 stores or 25,000 m² of roof surfaces. This often happens in combination with the safety coordination in the design and/or implementation phases.

Based on a thorough investigation (whether or not through deconstruction) and assessment of the existing situation, BB draws up the technical and administrative specifications, detailed quantity survey and a summarizing bill of quantity (tender entry form). Subsequently, BB monitors the tendering and compares the contractor bids.

BB leads the follow-up of the work (technical control, -technical cost, organizational) and assists in the provisional and final delivery, including reporting.

Team BB: ing. Freya Michiels, ir. arch. Dorien De Bonte, arch. ass. Ken Coolsaet, arch. ass. Tuur Van Dijck

Case: Green roof
The existing structure of the roof successively consisted of: support structure in concrete, bituminous waterproofing, screed of approx. 3 cm, insulation (XPS), filter fabric and about 60 cm of soil for an intensive green roof.

Since many infiltrations had occurred in the past the client wanted a total solution, including a green roof and space for a commercial area. This way, temporary sales stands could be placed on the green roof.

After a full restoration of the support structure of the existing roof, we opted for the following structure:

  • concrete support structure
  • two-layer bituminous waterproofing (P3 undercoat, APP 4 mm topcoat)
  • combined drainage layer with filter layer
  • substrate
  •  vegetation – planted sedum cuttings

In the commercial area, tiles on tile carriers were used and placed on the bituminous waterproofing. The tile carriers were adjusted in such a way that the tiles were at the same height as the green roof.

At the raised edges, drains and details, a gravel zone was used. If a problem would arise at one of these risk points, the gravel can be simply removed to provide a solution to the possible infiltration.

Entrance area 
The existing structure of the entrance area successively consisted of: a concrete support structure, a bituminous waterproofing of about 1 cm, a screed of about 10 cm and tiling of about 1 cm.

As the existing, outdated tiles were very slippery in rain and snow, a non-slip top layer for the entire zone was decided upon.

Finally, the following structure was opted for:

  • concrete support structure
  • two-layer bituminous waterproofing (P3 undercoat, APP 4 mm topcoat)
  • protection for the waterproofing: non-woven polyester fabric (≥ 250 g/m² total)
  • grit bottom layer
  • 6 cm thick clinker with sand in-fill

The difficulty of renovating this area consisted in matching the finished area with the existing parts: staircases, elevators and entrance. In addition, the renovation needed to cause as little disruption as possible during opening hours and the necessary safety measures had to be taken.