What does "plumb" refer to in construction?

In construction, "plumb" refers specifically to vertical alignment or straightness. This term is crucial because ensuring that a structure is plumb is vital for stability and aesthetic appeal. A plumb line, traditionally a string with a weight at the end, serves as a reference to achieve perfect vertical alignment.

Using a plumb line helps to ascertain whether walls, posts, or columns are upright and not leaning, which is essential for structural integrity. In roofing, while precise measurements are important, ensuring that the vertical elements of a building are plumb is a foundational aspect of the construction process. This concept is relevant across various types of construction work, as maintaining plumb conditions affects how well different components fit together and perform over time.