What is used to achieve accurate plumbing of the door frame?

Using a plumb bob is essential for ensuring that a door frame is accurately vertical, or "plumb." A plumb bob consists of a weight attached to a string, which utilizes gravity to provide a true vertical reference line. By lowering the plumb bob from the top of the door frame to the ground, workers can determine if the frame is leaning and make necessary adjustments to achieve perfect alignment.

Other methods, such as spirit levels, measuring tapes, and laser levels, are also useful for various measurements and leveling tasks. However, when it comes specifically to establishing a true vertical line, the plumb bob is the most effective tool. It offers a simple and reliable way to check the verticality of the door frame, critical for ensuring proper door operation and aesthetics.