Which of the following is not a primary design used to construct roofs?

The correct answer identifies "Cone" as not being a primary design typically used for roof construction. In roofing, the primary designs are generally established to provide optimal water drainage, structural integrity, and resistance to various environmental factors.

Pitched roofs are designed with a slope to facilitate water runoff, which minimizes the risk of water pooling and potential leaks. They are common in many residential and commercial buildings. Flat roofs, while they may appear minimalistic, are utilized in certain architectural styles and for specific functional requirements, such as rooftop gardens or mechanical equipment placement. Curved roofs, though less common, can effectively manage wind loads and contribute to unique architectural aesthetics, combining functionality with visual appeal.

In contrast, while conical roofs can be seen in some specialized structures, they are not considered one of the main categories of roofing design for most buildings. Their use is typically confined to specific architectural styles or historical models and does not represent a prevalent structural approach in contemporary construction practices.