Which of the following lines often indicates structural elements in MEP drawings?

Solid lines are used in MEP drawings to represent structural elements, as they provide a clear and defined representation of walls, beams, columns, and other structural components. The solid lines indicate the edges and outlines of these elements, making it easier for the reader to identify their location and extent within the building's design. This clarity is essential for professionals working with the drawings, as understanding the structural layout is critical for coordinating mechanical, electrical, and plumbing systems effectively within that framework.

Other types of lines, such as dashed lines, are typically used to signify elements that are not visible in a particular view, like hidden features or elements located above or below the current view. Dotted lines might indicate items like centerlines or boundaries, while wavy lines aren't standard in MEP drawings and may have specific meanings in different contexts but do not generally represent structural elements. Thus, solid lines are integral for showing the primary construction features in the drawings.