The headquarters of BESIX Infra and BESIX Unitec in Schelle recently underwent an impressive upgrade with the addition of three extra floors atop the existing four-story tower building. This expansion posed a significant technical challenge, requiring meticulous work to protect the building, its utilities, and its infrastructure. It also offered a chance to restructure the entire site, quite an achievement since the office had to stay open throughout the renovation, allowing employees to witness the transformation firsthand. Moreover, this project showcased the comprehensive solutions BESIX provides.
A necessary extension
The goal was to bring together the staff of BESIX Infra, Belasco, BESIX Unitec, BESIX Infra Support, and BESIX Unitec Automation under one roof in Schelle and accommodate future growth. This expansion was an opportunity for BESIX to demonstrate leadership in complex expansion/renovation works, water softening, consumption, local energy production, and storage. In addition to extending the newest office building, plans included a new warehouse, demolishing the site's oldest office building, and constructing a permeable parking lot.
One-stop shop at its best
The site transformation began in February 2023 with the office building extension. For the construction works, BESIX Infra and BESIX Unitec looked in the direction of our Vanhout colleagues. "Our expertise, the size of the project, and the location were the reasons for knocking on our door," Steven Berghmans, project manager at Vanhout, points out. BESIX Infra and BESIX Unitec carried out the preparatory works on and around the site, while Franki Foundations took care of the foundation works.
Caution and precision required
Adding three floors to the existing structure involved using an exoskeleton to avoid extra strain on the foundation and building stability. "Before we could start the construction work, we first demolished part of the oldest office building. Specifically, a 15-metre section in the middle of the building was removed. Under this section was a basement with a mass of cables and pipes between the two office buildings. Most of these had to remain in service. Therefore, before the demolition work started, we had them all encapsulated with plastic gutter elements to avoid damage from falling debris," Steven explains.
The high water levels at the site necessitated drainage, but a clay layer in the subsoil made groundwater lowering very difficult. "During the excavation work for the foundations, we had to take underground utilities into account. We literally had to navigate between the existing sewerage, gas pipe, water supply, and electricity cables. To protect these pipes from the pressure during the installation of the soil displacement foundation piles, we installed wooden dams in the subsoil,” Steven indicates.
“We also commissioned the necessary studies to properly assess the impact of drilling the piles under pressure on the existing basement. Since the exoskeleton was erected right next to the existing building, the piling machine was positioned 20 cm from the existing glass façade. So, we had to work very precisely. To avoid the high mast of the machine tilting towards the façade, we created a stable and perfectly flat surface."
Next step: renovation of the existing building
At the beginning of this month, phase two of the renovation project started. All staff members working on floors 0 to 3 moved to the new upper floors, so that the transformation of the lower floors could commence. At the end of the renovation project, the exoskeleton will have an overgrowth of climbing plants. "The purpose is twofold. Firstly, the planting should provide solar control by reducing direct sunlight during the summer months. In addition, the plants contribute to biodiversity,” Steven explains.
Safety first
Safety is even more important on this project than usual, as employees who worked in the building still had their workplace there. “We conducted a full risk analysis. Every hoisting movement had been thought through by all parties, from construction manager to safety coordinator and prevention consultant to contractor. We carried out the lifting operations to install the +4 floor slabs during last year’s Easter holidays. The offices were not in use then, so there was no safety issue for the employees," concludes Steven Berghmans.
As we speak, the renovation of our office building in Schelle is in full swing and on track to be completed by early 2025. Our colleagues will soon share a renewed workspace thanks to great teamwork!
