CPC33020 Bricklaying common mistakes
CPC33020 Bricklaying · Understand the traps and how to avoid them.
Calculating mortar or brick quantities from the wall face area alone, without subtracting openings or adding a wastage allowance, so the order is short on site.
Candidates memorise a bricks-per-square-metre figure and apply it mechanically to the overall elevation; they forget that doors, windows and piers change the net area, and they treat wastage as optional rather than a standard estimating step.
What to do instead
Work through a fixed sequence every time: measure the gross wall area, deduct all openings, add any piers or returns as separate items, multiply by the brick rate for the bond and unit size, then add a stated wastage percentage (commonly 5% for bricks and 10-15% for mortar). Write each line down so the assessor can follow the logic.
Setting out a rectangular building by measuring diagonals once and accepting the first reading, or squaring from only one corner instead of establishing a full profile.
Candidates rush to start laying and treat the 3-4-5 method as a formality; they do not repeat the diagonal check after adjustments, so small errors are carried into the whole footprint and the walls finish out of square.
What to do instead
Establish the profile with corner pegs and lines, use the 3-4-5 (or larger multiple) method at the first corner, then check both diagonals and adjust until they match within a few millimetres. Re-check diagonals after any peg is moved, and record the final measurements before laying the first course.
Laying a course without checking level and plumb at regular intervals, then trying to correct a lean several courses later by varying the bed thickness.
Candidates focus on speed and on the visual face of the work, believing the line will keep the course straight; they underestimate how quickly a small lean compounds and how hard it is to correct once the mortar has set.
What to do instead
Check level on every course at the corners and at least every metre along the line, and check plumb with a spirit level or plumb rule at each end and at openings. Correct immediately while the mortar is green. Keep bed and perp joints within the specified thickness range rather than using joints to compensate for error.
Producing perpend joints that are inconsistent in width and not fully filled, leaving voids behind the face, especially on the far side of the wall.
Candidates work only to the visible face, butter one end of the brick and rely on the trowel point to spread mortar, so the back of the joint is left hollow; they also fail to keep a consistent gauge for the perp spacing.
What to do instead
Butter both the bed and the cross joint, or fully fill the perp with a full trowel of mortar, and check by lifting a sample brick periodically to confirm full contact. Use a gauge rod or spacing guide for perp positions, and strike the joints only after confirming they are filled.
Mixing mortar by eye rather than to a stated ratio, adding water until it 'looks right', and using a batch that has begun to set by adding more water.
Candidates have seen experienced tradespeople work by feel and copy the appearance without the underlying ratio; they also want to avoid wasting a batch, so they retemper mortar that is past its usable life, which weakens it.
What to do instead
Measure sand and cement or lime with a consistent gauge (bucket or barrow count) and record the mix ratio on the batch. Add water gradually to a workable but not sloppy consistency. Discard mortar that has started to set; never retemper by adding water. Mix only what can be used within the working time.
Cutting bricks or blocks without dust suppression and without correct respiratory and eye protection, and using a disc cutter with the guard removed or the work piece unsupported.
Candidates treat cutting as a quick task and prioritise speed over control; they may not have internalised that silica dust exposure is a cumulative health hazard, and they underestimate kickback risk when a masonry unit is not clamped.
What to do instead
Use a wet saw or a cutter with water suppression or on-tool extraction, wear a suitable respirator and eye protection, and clamp the unit securely. Keep guards in place, check the blade for damage before use, and cut away from the body. Isolate the cutting area from other workers.
Erecting or working from scaffolding and trestles without checking that the platform is complete, that guardrails and toe boards are in place, and that the working platform height suits the course being laid.
Candidates see scaffolding as someone else's responsibility and adjust platform height ad hoc, sometimes standing on bricks or the guardrail to reach the top courses; they do not connect a missing component to a fall risk.
What to do instead
Before use, inspect the scaffold or trestle for completeness: platform boards, guardrails, mid-rails, toe boards and safe access. Adjust the platform so the work is between waist and shoulder height, and never stand on bricks, buckets or rails. Report missing components and do not use the platform until corrected.
Planning and sequencing a small job without identifying the setting-out datums, the bond, or the position of movement and articulation joints before work starts.
Candidates jump straight to laying because the drawing looks simple; they do not extract the information they need from the plan and specification, so they discover bond and joint requirements only when the assessor asks or when the wall has already been built.
What to do instead
Before starting, read the plan and specification and write a short work plan covering datums, bond, unit size, joint widths, articulation joint locations and tolerances. Confirm the plan with the supervisor if anything is unclear, then set out and check against it before laying the first course.
Building a wall that is expected to carry load or act as a veneer without correctly installing ties, damp-proof course, flashings or lintels in the right sequence.
Candidates treat these as minor accessories and install them after the masonry has been built, or omit the damp-proof course because it is hidden; they do not appreciate that these components must be bedded at the correct course and lapped correctly to function.
What to do instead
Sequence the work so the damp-proof course is laid on a full bed at the specified level, wall ties are placed at the specified spacing and slope to shed water, flashings and weepholes are built in as the work rises, and lintels are bedded with the correct bearing length. Check each item against the specification before covering it up.
Finishing joints and cleaning down the wall too early or with too strong a mix, leaving smeared mortar or eroded joints on the facework.
Candidates want a tidy finish before the assessor sees the work, so they strike and brush while the mortar is still plastic and use a strong acid or neat hydrochloric wash that attacks the mortar and stains the masonry.
What to do instead
Let the mortar take up until it is thumbprint firm before striking, use the specified joint profile, and brush with a dry or slightly damp soft brush. Remove smears as they occur. For cleaning, use the weakest effective method specified, pre-wet the wall, test on a small area, and rinse thoroughly.