On the edge of the city centre, looking out over the gently streaming Schelde river, container ships slowly manoeuvring in and out of the harbour, can the location for a prestigious building project in the harbour city of Antwerp be more unique? The renovation and extension of an early 19th century building situated on this spot, was commissioned by a private client who wanted to transform the two most upper floors of the old warehouse into office spaces and wished to realise the construction of a three-storey high penthouse on top. Considering the urban and technical limitations, for the building team, this would definitely be a challenging task.
As the functioning of the ground and first floor offices was to be assured during the execution of the construction works, the design task became even more complex. In order to bear the extra weight of the extension, the existing foundations had to be consolidated. Also as the bearing capacity of the existing structure, made out of concrete columns and beams, had its restrictions, special measures had to be taken to minimize the extra weight of the additional storeys. A steel construction of columns and beams dimensioned according to the grid of the existing concrete structure, was placed and assembled on top of the building. Floors made out of I-shaped wooden beams, structural walls covered by plasterboard and honeycomb plates supporting a thin layer of stone, all measures to reduce the additional load brought upon the existing structure.
The spatial organisation of the three storey high penthouse is structured by a rectangular void perforating the two dividing floors within the axes of the horizontal grid and shifted along its vertical axes. Closed boxes housing specific living functions are placed between the floor slabs. According to their use and spatial appearance, they are covered with different materials such as glass, wood, stone, and plasterboard. Due to the open plan and perforated floor levels, the dwelling achieves an unusual spatial character. The sunlight entering the penthouse from the southern glass façade shining though the voids, provides sun and light throughout the three-storey penthouse.
As the penthouse was placed on top of an existing building, the original volume of the warehouse was going to be altered in a dramatic way. Nevertheless the expression of the early 19th century façade from which the proportions are based on the golden section, had to be respected. Therefore, the dimensions of the penthouses façade were based on the same mathematical system.
The glass façade of the fourth and sixth floor are placed backward a couple of meters which makes the fifth floor appear as a large glass box hanging over the old façade. In this way the old and the new are harmoniously combined but stay separated at the same time.