The fixed roof of the Vista Alegre Facilities is a Schwelder-type dome, composed of steel parallels, meridians and diagonals, of 1/8 sag-span ratio. At its perimeter, it is supported by concrete pillars.
The fixed roof consists of one layer made up of commercial steel profiles (IPE). At the central part of the roof, there is a steel compression ring of 50,00 m diameter on which 12 steel masts are placed in order to support the moveable roof-part when lifted.
This moveable roof-part consists of a 12,00 m sag pneumatic lens-shaped cover, held together by a perimetric steel ring of 50,00 m diameter. Its upper membrane is made of PVC polyester; its lower one is a transparent velaglass-sheet, sustained by a mesh of cables of 1,50x1,50 m2 each square.
This moveable part of the roof can be lifted 10,00 m up the fixed roof, hanging from the 12 masts which are supported by the main roof.