Does plan north always differ from true north?

Plan north and true north are two different directional references used in architectural and engineering drawings. Plan north refers to the upward direction on a drawing, which may not always align with true north, the direction toward the geographic North Pole.

Understanding that plan north often differs from true north is crucial in interpreting construction documents accurately. The reason option B is the correct choice is that although plan north and true north can differ, this difference—known as the magnetic declination—can remain fairly consistent for a particular location. Depending on the context, plan north is typically established based on how the building is situated or aligned with respect to true north, but this alignment does not change frequently over time.

Additionally, it is important to note that plan north can be adjusted for various design purposes, which is why it can differ from true north in any specific project. The other options do not accurately describe this relationship: while some may imply a static difference, others incorrectly state that they are irrelevant or affected by transient changes. Understanding the difference helps professionals maintain accuracy in design and align construction with real-world geography.