What tool do masons hang to maintain a straight line during construction?

Masons use a string line to maintain a straight line during construction because it provides a visual guide that can be easily tensioned between two points. This tool is crucial in ensuring that the edges of walls or other structures are straight and aligned properly. The string line is particularly effective for laying bricks or blocks in long, straight runs, helping masons achieve consistency in alignment and spacing.

While other tools like chalk lines, laser levels, and plumb lines serve important purposes in masonry and construction, they do not function in the same way as a string line. A chalk line is typically used to mark straight lines on surfaces, a laser level provides a precise horizontal or vertical reference over longer distances, and a plumb line helps ensure vertical accuracy. However, when it comes to maintaining a straight horizontal line over larger spans during the masonry process, the string line is the preferred tool.