What is the defining characteristic of a slab door?

A slab door is defined primarily by its flat, solid surface, which differentiates it from other door types that may include frames, panels, or additional structural components. The absence of protruding elements or complex designs embodies the simplicity and straightforwardness of a slab door. This characteristic makes it a common choice for interior spaces where aesthetics can be minimalistic.

In contrast, choices focusing on a frame, reinforcement materials, or insulation features do not align with the fundamental nature of a slab door. Such doors are typically unembellished and provide a straightforward barrier without needing extra features like insulation or reinforced materials, which are more common in specialized doors designed for specific purposes. Therefore, the defining characteristic as a flat construction effectively captures the essence of what a slab door is.