On exterior wall drawings, which depiction best represents the boundary of the wall?

• A. A solid filled rectangle
• B. A dashed line with arrowheads
• C. A thick single line
• D. A pair of parallel lines

Answer: (D)

In exterior wall drawings the boundary of the wall is shown with a pair of parallel lines. This represents the wall’s thickness and the envelope of the building in plan view, clearly marking where the wall starts and ends and where its inner and outer faces lie. Using two parallel lines communicates the actual boundary more accurately than other depictions. A solid filled rectangle would imply a solid mass rather than the boundary of the wall. A dashed line with arrowheads is typically for dimension or hidden features, not the wall boundary in plan. A single thick line can indicate a wall location but doesn’t convey the wall thickness as effectively as two parallel lines.