How are joists represented in a set of plans?

• A. Solid lines
• B. Dashed lines
• C. Dotted lines
• D. Centerlines

Answer: (A)

In plan drawings, how a structural member appears tells you what you’re actually seeing from above. Joists run across the floor and their edges are visible in the plan, so they’re drawn with solid lines to show the true edges and position of the joists in the floor plane. Dashed lines would indicate something hidden or above/behind the plane, not the joists themselves in the visible plan view. Centerlines are used to mark the axis of a member for alignment, not to depict the edge of the joist. So solid lines are the correct way to represent joists on a plan.