From office building to apartment building

An enormous amount is possible in the transformation of buildings, provided that a complete and reliable picture of the structure can be formed based on the original calculations, drawings and foundation data. Engineering firm SWINN proved this in the transformation of the former UWV office in The Hague into a high-quality and sustainable apartment complex.

Text | Lieke van Zuilekom   Image | Slokker Construction Group

"Prior to the purchase, we conducted a brief preliminary study of the technical possibilities of the building blocks," says Erik Verweij, project manager at SWINN. "Then, on behalf of Amvest Development Real Estate, we deepened the study. We calculated whether the (partially covered) technical areas on the upper floors could be removed to make room for two new residential floors. We expressly took into account the latest standards and our client's Schedule of Requirements. Amvest did not want lightweight constructions but solid buildings with solid, preferably concrete floors. This was feasible for several reasons. First of all, the three building blocks from the 1970s were designed with sufficient reserve capacity in the construction. In addition, the floor loads of the office functions were somewhat higher than current residential building loads. In addition, the building has already proven itself, so the structural standards allow room to assign a little more capacity to the structure." SWINN mapped all the neutral zones in the storey floors so that recesses could be made for ventilation ducts, for example. For the remaining recesses, all floors were checked. Where necessary, the structure was repaired and reinforced with adhesive reinforcement.

In the design by PBV Architects and Klunder Architects, the facades of the building blocks are stripped down to the shell and rebuilt. "The lower layer with masonry frames is accommodated by the existing support structure, with local structural additions," Verweij said. "Above that, facade cladding was chosen, saving weight." Initially, all building blocks were connected by an office bridge on the 2nd and 3rd floors. "Between building blocks 1 and 2, this connection was removed. Instead, the connection between blocks 2 and 3 was extended, by adding apartments on the ground and second floors. This has created a U-shaped residential block. All building facades have balconies, which unfortunately could not be supported by the floor edges. Instead, the balconies are self-supporting. All balconies have a direct transfer to the parking basement deck or are suspended from the new building floor. A steel retaining structure was added under the parking basement deck, which further transfers the loads to the existing structure."