Bending/forming instructions vary by sheet material. Always check the installation instructions of the relevant sheet material.
But in general, some of our sheets can be cold-curved for arched shapes, provided the relevant Palram specifications for minimum radius in cold-curving are followed.
Rigid flat sheets can be cold-curved in any direction.
Corrugated sheets can be cold arched "along the grain" of the corrugation (lengthwise). Corrugated sheets cannot be curved/arched "against the grain." That is, do not bend perpendicular to the direction of the ribs.
Like corrugated sheets, multiwall sheets can be arched only "along the grain" of multiwall (lengthwise).
Our Palight Trimboard "lumber-style" boards can be heat formed in any direction, with the proper heating equipment and forming jig.
Again, see the installation guidelines for each material for specific instructions.