Masonry and Bricklaying Support
This domain tests the support tasks around masonry: mixing mortar to the right type and consistency, laying out courses to gauge, keeping joints uniform, installing flashing and weep holes, and handling and cutting units safely. Expect questions on mortar types, bond patterns, story poles, cavity details, and silica control.
Mortar and materials
- Mortar type sets the strength and durability. Type N is a general-purpose mix, Type S is stronger for load-bearing and lateral resistance, and Type M is the highest strength, used where maximum compressive strength is needed. Proportions are specified by the project, so follow the mix design rather than memory.
- Mix to a workable, buttery consistency that holds a ridge on the trowel. Too much water weakens the mortar and causes shrinkage.
- Do not use mortar that has begun to set; retempering is limited by the specification.
- Keep units dry or damp as required: very dry brick pulls water from mortar too quickly and weak mortar does not bond; saturated units can float.
Laying out and laying
- Set a story pole to establish course heights before laying begins, and build corner leads first.
- Common modular brick with a 10 mm joint gives courses of about 67 mm; three courses equal roughly 200 mm, which makes course counting simple.
- A running (stretcher) bond offsets units by half a unit; keep head and bed joints uniform and tool them when the mortar is thumbprint-hard.
- Use a mason's line and line blocks to keep each course straight and level.
Flashing, weep holes, and grout
- Install flashing at the base of the cavity and at openings, with weep holes above it, commonly spaced about 800 mm apart.
- Keep the cavity clear of mortar droppings so water can reach the weep holes.
- Reinforce block walls as specified and grout cores in lifts, consolidating each lift.
- Cut units with a wet saw or dust-controlled method to limit respirable silica.
Worked example
A wall is specified at 2.700 m from the foundation to the bearing point, using modular brick with 10 mm joints. At about 67 mm per course, that is roughly 40 courses. The crew sets a story pole at 40 courses, then adjusts the bed joint at the base to absorb the small remainder rather than spreading the error across every course. Corner leads are built to the pole, and the line is strung between them for the field brick.
Traps that cost marks
- Spreading a layout error by adjusting every joint instead of correcting at the base or at a course line.
- Leaving mortar in the cavity that blocks weep holes.
- Using mortar that has already begun to set.
- Dry-cutting units without dust control.