A perpend gauge rod is a lath marked out with the perpend gauge, which a bricklayer uses as a measuring stick while laying bricks. Where the storey rod sets the height of the courses, the perpend gauge rod sets the spacing along the length of the wall.
Why bricklayers use one
For neat brickwork, the perpends of successive courses have to sit exactly in the intended pattern: directly above one another every other course in stretcher bond, and according to the pattern of the bond in English and Flemish bond. Measuring afresh each time will not achieve this. Small variations in the bricks and the cross joints accumulate, and after three metres the setting out is visibly out of line.
Working out the average perpend gauge once and marking it on a rod gives the bricklayer a fixed reference. Hold the rod along the course and you can see immediately where each brick belongs.
Making the rod
- Work out the perpend gauge — lay 10 stretchers tight against one another and 20 headers above them. The difference between the two rows equals 10 cross joints. Add that difference to the length of the headers and divide out: that is the perpend gauge.
- Mark it on the rod — set the dimension out repeatedly from one end of a straight, dry lath.
- Notch it, don’t pencil it — a saw or knife cut stays readable. Pencil and marker lines disappear under mortar dust and site damp within half a day’s work.
Practical tips
- Make a new rod for each job. The perpend gauge varies from batch to batch, even within the same brick format. A rod from a previous job rarely fits.
- Measure with bricks from the same delivery — the ones actually going into the wall.
- Combine it with a corner profile. The gauge rod controls the horizontal setting out, the profile and storey rod the height. Together they keep the whole face in line.
- Set out from the openings. Distribute the bricks so that windows and corners need as few cut pieces as possible. That is exactly where the gauge rod pays for itself.
Related terms
- Perpend gauge
- Bricklaying
- Perpend
- Bond pattern
- Brick sizes
- Queen closer
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