A plumb bob is a pointed weight hung from a string that uses gravity to establish a true vertical line, letting a mason check whether a wall, corner, or chimney is plumb rather than leaning.
The tool is simple: a weighted point hangs freely from a string, and where it settles is straight down, no batteries or calibration required. Masons still use one alongside laser levels because it works in wind-sheltered spots a laser can't reach, doesn't need a sightline, and never drifts out of calibration. Holding a plumb bob against a corner or a chimney face and reading the gap top to bottom is still one of the fastest, most reliable ways to check true vertical on site.
On a chimney repair, a plumb bob is often the first tool out of the truck. It tells us whether a lean is old and stable, something the chimney was built with decades ago, or new and active, which changes the whole scope of the repair. That distinction matters a lot before we start pulling brick or planning a rebuild, since a chimney that's actively moving needs the cause addressed, not just the symptom.
More masonry vocabulary from the glossary.
The services where this term comes up.
Chelo's Brick & Stone serves Hillsville, Galax, Wytheville, Fancy Gap, and Independence, VA. Call for a straight answer and a free on-site estimate.
