American White Oak by Rudy de Keyser
Flooring at the Museum aan de Stroom has been installed in high quality American white oak
The city of Antwerp is undertaking an ambitious urban regeneration programme in its historic dockland. At the heart of this urban renewal, stands the Museum aan de Stroom (Museum on the River), designed by Neutelings Riedijk Architects, a major new landmark encapsulating the city’s collective memory of its maritime heritage. ‘We wanted to create the atmosphere of a treasure box where visitors will discover thousands of exhibits from Antwerp’s rich maritime past,’ says Mark Sette, one of the project architects.
The building’s cubic design alludes to the familiar sight of refurbished warehouses on the Bonaparte Dock, one of Antwerp’s oldest quaysides. The tower rests on a central concrete core of 13 x 13m. Huge metal frames were fixed onto this core to extend the floors to 38.7 x 38.7m. Different floor levels are staggered like interlocking cubes to create large overhangs. This had a direct influence on how the American white oak flooring was designed.
‘When we cast the concrete floors, we knew the load would make our floor level sink,’ says Wim Arits, one of the senior project managers. ‘This is why we set the angle of our steel frame 15cm above the finished floor level.’ Originally, the architects wanted the oak flooring to be as traditional as possible and situated on double solid joists to support bearing loads of up to 500kg. They also had precise size and quality specifications, with the flooring strips produced to a uniform length of 3.5m, width of 150mm and thickness of 35mm in prime quality oak.
After several weeks’ discussion, the team elected to install a sub-base of calcium sulphate slabs under the floor. This offers several advantages: first it provides extra mechanical resistance to oak flooring, preventing it from creaking after a few years. Second, it provides more flexibility for installing museum showcases as it leaves a passage below the calcium sulphate slabs for cabling. Third, whereas a solid wood joist system would haveincreased the floors’ moisture content, the slabs remain dry, reducing the number of expansion joints on each floor level.
Slabs rested on adjustable jack studs and were set once the concrete floors had stabilised to their finished level. In view of the large surface area (7,000m²) and the high standards required, the flooring contractor Rudy De Keyser Wood Industry NV suggested using American white oak. Shorter strips are used along the wall edges to stagger the flooring joints, whereas in the centre of the floor, the strips measure between 3m and 4m long, in keeping with the scale of the large exhibition spaces.
The floor strips are joined together with a classic tongue and groove system, and then glued and nailed onto the calcium sulphate slabs. The wearing course on each floor strip is 8mm thick and has been treated with an oil finish plus a salt-based fire retardant, particularly in the fire exit routes. ‘Despite these different coatings, the American white oak colouring has remained consistent throughout the building,’ comments Sette. ‘And we are very happy with the end result.’