Alligator Scale cladding sheets: Special product development for the Bilbao Arena sports complex

Bilbao Arena is a modern new sports complex in Bilbao's suburb of Miribilla, where the architecture of the two buildings imitates their surroundings. In the course of this project, a new product was developed - the characteristic cladding sheets named Alligator Scale, designed by the architects of ACXT. The steel for the facade made of rhombus shaped steel sheets in different shades of green was delivered by ArcelorMittal Construction Spain.

Detailed information

The building is located on two plots of 17 821 m2 and 6029 m2 respectively in Miribilla, Bilbao, Spain. Due to the different height levels of the area, an organic design with low visual impact was proposed which aims for the maximum integration of the buildings into the surrounding public park.

Bilbao Arena is more than a conventional sports centre: its main court offers seating for thousands of spectators as it is home to the famous local basketball team, Bizkaia Bilbao Basket, and holds some very important tournaments. Furthermore, the facility offers the residents of Miribilla a swimming pool, a gym, and smaller courts for football or basketball games.

The project, designed by Javier Pérez Uribarri and Nicolás Espinosa at ACTX of the engineering company IDOM, aims for the sustainable integration of the building into its surroundings. It consists of two separate volumes.

The main hall

The larger building that contains the main court has an organic shape and is located on the higher part of the plot. Its structure imitates the trees of the adjoining park. The upper part of the building is clad in rhombus-shaped steel plates in different shades of green like a tree tops, supported by diagonal columns resembling trunks. The cladding was made with steel from ArcelorMittal and covers the service installations like heating and ventilation.

With a capacity of more than 8500 spectators, the big central court can be used for big basketball tournaments. One of the most important characteristics of the central court is its flexibility to adapt to different situations as it can host big sports events and, at the same time, offer three smaller courts for everyday needs like smaller indoor football or basketball games and trainings. At big events, its operation is completely independent from all the other installations with a separate entrance area.

The main court can also welcome concerts and music events thanks to its exceptional acoustics.

On a total surface of 25 985 m2, it offers changing rooms for tournaments, a medical care area, group changing rooms, storage rooms, and premises for other uses. The main court is equipped with two levels of stands, one stand being permant wheras the second can be removed.

The multisports centre

The second building houses the gym and the swimming pool and looks similar to the rocky base of the tree construction above. The 26m pool has six lanes, and there is a smaller pool for children. The 520m2 gym can also be subdivided into three areas if needed. There are two general changing rooms for men and women and four for groups, separate facilities for instructors and lifeguards, offices for administration, and maintenance and service installations covering a total constructed area of 4823 m2.

Both volumes adapt to the slopes of the plot with various levels and entrances to the complex. The pedestrian entrances to the facilities used every day are close to the adjoining buildings whereas as the entrance used for big events is at some distance in order to avoid possible disturbances of the neighbours. A public car park offers spaces for 250 cars.

A new development for the steel facade

More than 10 000 m2 steel plates in six different colours for the exteriors, 9000 m2 of black coated corrugated steel sheets and 5000 m2 of galvanised steel sheets for the interiors, were supplied by ArcelorMittal Construction Spain.

A new product was developed for this project: The Aligator Scale cladding sheets, designed by the architects of ACXT, are now part of ArcelorMittal Construction Spain's Arval product range. They consists of 0.7 mm steel sheets with a surface finish of 25 μ of PVDF coating. Dimensions vary between 75 and 150 cm.

The rhombus-shaped steel sheets are fixed on diagonal substructure with separations of 75 cm in galvanised steel.

Project information

  • Bilbao
  • Spain
  • Architect:
  • 2007- 2010
  • Client:
    DFA - DFB Diputación Foral de Bizkaia y Ayuntamiento de Bilbao
  • Engineering office:
  • Contractors:
    Sobrino S.A., Cycasa S.A., Morkaitz S.A. Bilbao Kirolak: Facility management
  • Photographers:
    ©Bilbao Kirolak- Miguel Toña