How to check for plumb using a plumb-bob

Shop for Plumb-Bobs

Checking for plumb

Step 1 – Mark point

With a pencil or marker, mark a point 50mm (2 inches) in from the wall or object you want to check for plumb.

Step 2 – Fix nail and attach string

Fix a nail or sturdy pin into the marked point and tie your string to it. Your string should be at least as long as the wall or object is high.

Step 3 – Suspend plumb-bob

Suspend the plumb-bob by the now attached string. The plumb-bob should be able to swing freely and rest about 12.5mm (½ inch) off the ground. You may need to adjust the string if it is too long or too short.

Step 4 – Allow plumb-bob to stop swinging

Make sure the string is taut and allow the plumb-bob to stop swinging and come to a dead halt. You can speed this process up by steadying the weight with your hand or letting the tip touch the ground momentarily before gently lifting it off the ground again.

If you are working outdoors in the wind, then the plumb-bob may be difficult to stop and may not give an accurate reading. A heavier plumb-bob is often useful here.

Step 5 – Mark point below plumb-bob

Once the plumb-bob has stopped swinging it will be directly below the mark above. With a pencil or marker, mark the point beneath the pointed tip of the plumb-bob.

Step 6 – Measure distance

Once the plumb-bob is stationary, measure the distance from the wall to the tip of the plumb-bob (or the marked point) and if it is exactly 5cm (2 inches) away from the wall then you know that your wall is plumb. Job done!