It depends upon what type of design customer wants to implement.
Mansard type roof.
Mansard is a four sided roof with double slopes on each side so its sides can either be curved or flat.
Mansard or french roofs are quite similar to a gambrel roof design since they are also made up of four sides.
In cross section the straight sided mansard can appear like a gambrel roof but it differs from the gambrel by displaying the same profile on all sides.
The steep roof with windows creates an additional floor of habitable space a garret and reduces the overall height of the roof for a given number of habitable stories.
One such important type of the roof is the mansard roof.
The word mansard means an actual attic inside the roof not just the shape of the roof.
A mansard or mansard roof also called a french roof or curb roof is a four sided gambrel style hip roof characterized by two slopes on each of its sides with the lower slope punctured by dormer windows at a steeper angle than the upper.
There is a sort of visible distinction between flat roofs and mansard roofs.
Mansard roof type of roof having two slopes on every side the lower slope being considerably steeper than the upper.
But you cannot misunderstand them as straight panel roofs.