Brick and Block Masonry Construction
Core concepts
Walling depends on four controls held at once: level, plumb, line and gauge. If any one drifts, the wall is wrong even if each course looks acceptable.
Bonds and units
Learn stretcher, header, English, Flemish, English garden wall and rat-trap bond. A queen closer (half a brick) closes the bond at quoins; a half bat and three-quarter bat finish odd lengths. Never make a joint wider to save cutting. Hollow concrete blocks are laid in stack or running bond with the cores aligned vertically where grouting is required.
Joints and bedding
Joints are typically 10 mm, within a tolerance of about 8 to 12 mm, and must be full: a solid bed, filled perpends, and mortar squashed rather than dropped in. Bricks are laid frog up so the frog fills with mortar and forms a mechanical key. Blocks must be clean and, in hot dry weather, lightly wetted so they do not suck water from the mortar.
Coursing
Use a storey rod to set out course heights. A 400 x 200 x 200 mm block with a 10 mm joint gives a 210 mm module, so 10 courses rise 2.10 m and 16 courses reach about 3.36 m.
Working practice
Build to a line stretched between corner blocks, check plumb on both faces, and raise the line as work proceeds. Do not raise a wall more than about 1.0 to 1.5 m in a day with cement mortar. Leave toothing or a wall tie system where future work will join, fit the damp-proof course fully across the wall, and give lintels at least 150 mm bearing each end.
Traps in questions
Frog down, joint thickness used as a levelling device, blocks not wetted, curing skipped, plumb checked on one face only, and no allowance made for the joint in coursing calculations.