Roof girders are horizontal prestressed structural elements. In addition to prestressed, they can also be classically reinforced. The dimensions of the cross-section depend on the span and the associated bearing surface.

A - Type beams are the roof's primary  girders with a double slope. These beams are with variable cross-section and prestressed. They are produced in segments molds - by ejecting segments from the middle to the ends, a shorter girder and less height is obtained.
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2 types of A beams are produced:
- A 150 with a slope of 3 % (for "stacked roof system"), maximum length 34 m
- A180 with a slope of 10% (roofing with thermal panels), maximum length 25 m