Course Height Out of Tolerance
A bricklayer is building a 3.6 m high wall to a datum. After laying eight courses, a check with a straightedge and level shows the top of the eighth course is 25 mm above where it should be against the gauge. The bricklayer says the bricks vary in height and the mortar beds have been made thicker to 'even out'. The wall is only eight courses high, the mortar is still green, and the next lift is due after lunch. The supervisor must decide whether to continue or correct.
1. Why has the wall gained height, and why is thickening the beds the wrong response?
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The wall has gained 25 mm over eight courses because the bricklayer has compensated for brick height variation by increasing mortar bed thickness rather than adjusting the gauge. Each thickened bed adds up cumulatively. Thick beds reduce the compressive strength and increase shrinkage, and they hide the real problem: brick variation should be managed by selecting and sorting bricks, using a gauge rod, and keeping beds within the specified range. Continuing would compound the error and make later courses and openings misalign. The correct response is to recognise that the gauge has been lost and that the cause is the method, not the bricks alone.
2. Given the mortar is green and the wall is low, what corrective action is appropriate?
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Because the mortar is still green and the wall is only eight courses high, the economical and technically sound action is to take down and rebuild the affected courses to the correct gauge before the mortar hardens. Trying to pull the wall back into line by reducing later beds would create thin, weak joints and a visible step. The bricklayer should set up a gauge rod, check brick heights, and lay beds within the specified thickness, adjusting by sorting bricks rather than thickening joints. The supervisor should record the nonconformity, verify the datum, and inspect the rebuilt work before the next lift. Continuing and 'correcting later' would be the wrong judgement because the error is already 25 mm and growing.