What type of plans are primarily depicted in 2D?

Floor plans are primarily depicted in 2D as they provide a bird's-eye view representation of a space, detailing the layout of rooms, walls, doors, and windows from above. They serve as a foundational aspect of architectural design, allowing for the visualization of spatial relationships and the arrangement of elements within a building.

In contrast, elevation plans show the vertical faces of the structure, presenting a two-dimensional view that illustrates height, materials, and architectural features but does not convey the layout in the same comprehensive manner as floor plans. Shop plans, often used in cabinet and millwork production, can include 2D details but may also integrate 3D elements, focusing more on specifications for construction rather than spatial layout. Section plans depict a cut-through view of the building, providing insight into the internal elements and heights but not serving as a flat layout like floor plans.

Therefore, the defining characteristic of 2D representation among the options is best captured by floor plans, which directly communicate the dimensional arrangement of spaces within a structure.