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 Miribilla, the architecture of the two buildings imitates their surroundings. In course of this project a new product was developed - the characteristic cladding sheets with the name Aligator Scale, designed by the architects of ACXT. The steel for its façade made of rhombus shaped steel sheets in different shades of green and was delivered by ArcelorMittal Construction Spain.

Detailed information

The building is located on two plots of 17.821 m2 and 6.029 m2 respectively in Miribilla, Bilbao. 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 center: its main court offers seating for various thousand spectators since it is home to the famous local basketball team, Bizkaia Bilbao Basket and celebrates some important competitions. 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 of ACTX, the architectural study 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 of 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 8.500 spectators, the big central court can be used for big basketball competitions. 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 3 smaller courts for everyday needs like smaller indoor football or basketball games and trainings. At big events its operations 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 competitions, 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 Center

The second building houses the gym and the swimming pool and seems like the rocky base of the tree construction above. The 26m pool has 6 lanes, there is a smaller pool for children. The 520m2 gym can also be subdivided into 3 areas if needed. There are 2 general changing rooms for men and women, 4 for groups, and separate facilities for instructors and lifeguards, offices for administration and maintenance and service installations, covering a total constructed area of  4.823 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 parking offers spaces for 250 cars.

New development for the steel facade

More than 10.000 m2 steel plates in 6 different colours for the exteriors, 9.000 m2 black coated corrugated steel sheets and 5.000 m2 of galvanized steel sheets, both for interiors, were supplied by ArcelorMittal Construction Spain.

In course of this project a new product was developed: The cladding sheets with the name Aligator Scale, designed by the architects of ACXT, is now part of ArcelorMittal Construction Spain's Arval product range. It consists of 0.7 mm steel sheets, with a surface finish of 25 μ of PVDF coating. Its dimensions vary between 75 and 150 cm.

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

Project Information

  • Bilbao
  • Spain
  • Architects:
  • 2007- 2010
  • Client:
    DFA - DFB Diputación Foral de Bizkaia y Ayuntamiento de Bilbao
  • Engineering office:
  • Contractor:
    Sobrino S.A., Cycasa S.A., Morkaitz S.A. Bilbao Kirolak: Facility Management
  • Photographer:
    ©Bilbao Kirolak- Miguel Toña , ©ArcelorMittal