Masonry
What this domain tests
This section examines brick and block bonds, mortar joints, how walls are raised plumb and level, and how junctions and openings are handled.
Core rules and concepts
- English bond: alternate courses of headers and stretchers; strongest bond for 230 mm walls; a queen closer is placed next to the quoin header to break the joint.
- Flemish bond: header and stretcher alternate in every course; neater face but weaker than English bond.
- Stretcher bond: used for half-brick (115 mm) partition walls.
- Rat-trap bond: bricks laid on edge to leave a cavity, saving bricks and mortar and improving insulation.
- Mortar joints 10 mm thick, fully filled; raked later where plaster is to be applied, but not deeper than 12 mm.
- Rules on site: bricks soaked before laying, frog filled and up, each course checked with spirit level and plumb bob, corners raised first and connected with a line, walls toothed at junctions, no vertical joint over 10 mm, through stones in stone masonry.
- Blocks: AAC blocks are not soaked and use thin-bed adhesive mortar.
Worked example
Brickwork in a 230 mm wall around a room of internal size 4 m × 3 m, height 3 m, deducting one door 1.0 × 2.1 m. Long walls (2 nos): 4 + 2 × 0.23 = 4.46 m each → 2 × 4.46 × 0.23 × 3 = 6.155 m³. Short walls (2 nos): 3.00 m each (fitting between long walls) → 2 × 3.00 × 0.23 × 3 = 4.140 m³. Total 10.295 m³, less door 1.0 × 2.1 × 0.23 = 0.483 m³ → 9.812 m³, say 9.81 m³.
Traps that cost marks
Laying bricks frog downward; making joints 20 mm thick "for strength"; soaking AAC blocks; leaving a straight vertical joint (no bond) at a corner; forgetting to deduct openings in the quantity.