Adding a retractable roof over San Mames may run along the schemes in Warsaw or in Amsterdam. Depending on solution used it might cost €20-30 million.

According to El Correo, engineers from Idom (company behind San Mames design) are evaluating the possibility of adding a retractable roof over the Bilbao stadium. Reasoning behind it has been known for months: despite vast roof over the stands, the north Atlantic wind and rain make people in the lower tier soaked on some matchdays.

Two options are said to be on the table. First one, less intrusive and cheaper, could be the cable-membrane combination known from Frankfurt, Warsaw and Bucharest. Adding such retractable roof over San Mames might cost roughly €20 million ($22m).

Adding a heavier truss-based structure with two or more sliding panels (as known from Amsterdam ArenA or Stade Pierre Mauroy) could require up to 50% more investment, some €30 million ($33.5m). It would also be more invasive and need more changes to the original structure. Both options are presented in the below graphic we made for you:

Either  way, adding a new retractable roof is a complicated issue in a stadium that already has a well-calculated and complete roof. Changes are required in the design that already cost some €211 million. Ironically, addition of a retractable roof was contemplated before groundbreaking, but discarded as too expensive…