Alkmaar’s new Cultural Centre on strategically situated Canadaplein square on the edge of the historical town centre houses the Municipal History Museum, the Central Library and the Artiance Music School. The architectural challenge was to combine three different functions in one building on a narrow site, and integrate an existing structure: the former 1970’s Interkruis building. Although comprising one volume with a common auditorium, the design preserves the individuality of the three institutions, which are set side by side in an east-west array so that each faces onto the main square.
The library to the south is largely contained in the former Interkruis building. Warm materials like Oregon pine and sandy-coloured linoleum give it a restful, comfortable atmosphere. A succession of patios and cleverly arranged empty spaces allow daylight to penetrate deep into the building.
The music school to the north has a three-storey entrance onto the square. Steel and birch doors and black linoleum add further elegance. Daylight pours in from the glazing at the end of corridors.
The municipal museum, requiring minimum daylight, occupies the central strip. Its glazed roof gives the feel of a covered urban square leading to the central hall and lends this compact structure a striking transparency and lightness.
A major feature is the common auditorium which hangs in the central hall like a weightless white box.
The old building has a skin of wooden slats which cover the glass facade of the new structure while at the same time giving an enticing glimpse of old-new contrast. The overall layered effect is soft and transparent, creating an ideal blend with nearby buildings: a large, imposing church and the small buildings of the old town centre.
On the technical level, the pre-stressed concrete floors belonging to the former building were preserved since their carrying capacity of 6kN/mq was sufficient for the building’s new function. The ground floor slab did not meet specifications, however, and was replaced with a new 230 mm composite flooring system laid on the existing foundations. Where necessary, steel beams were placed for extra support.
During excavation of the basement, high groundwater level was a problem. The building pit had to be drained continuously until sufficient weight had been added to counter groundwater pressure. Since watertight walls and floors in the basement allowing fail-safe moisture control are prime requirements for a museum containing valuable works of art, intricately structured horizontal reinforcement and concrete with a water/cement ratio of <0.45 were used.
Integrated reinforcement steel beams allowed considerable reduction of total floor thickness.
Part of the building’s supporting framework functions three-dimensionally. Walls are not placed on top of each other but “hang” between other cross-placed walls. Indeed, it is sometimes unclear how they transfer their load. The effect is often surprising, accentuated by the frequent use of voids.
Several staircases are 120 mm prefab concrete steps protruding 1.80 m from the concrete walls. As steps and landings were mounted after the walls were constructed, placement required the utmost accuracy.