Which component forms the top surface of a container?

The roof panel is the component that forms the top surface of a container. It plays a crucial role in providing structural integrity and protection against environmental elements. The roof panel is designed to withstand various weather conditions such as rain, snow, and UV rays, thereby safeguarding the contents stored inside the container from potential damage.

In addition to its protective function, the roof panel contributes to the overall strength and security of the container, ensuring it holds its shape and can be stacked safely when transported. Other components, such as joint strips, flooring, and steps, serve different functions within the container's structure. Joint strips help to seal connections between different panels, flooring provides a base for cargo, and steps offer access to the container's top but do not contribute to the top surface itself. This makes the roof panel the key element defining the upper boundary of the container.