Masonry NC II flashcards
Masonry NC II · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Toolbox talk record
- A short safety briefing log stating topic, date, and attendee signatures. It documents that hazards and controls were communicated before work began.
- Request for information
- A written query to the designer when drawings or specifications are unclear or conflict. Work on the affected item stops until a written answer is issued.
- Fall protection threshold
- Fall protection is required at heights of two metres or more, or wherever a fall hazard exists over an edge, opening, or impalement risk.
- Silica dust control hierarchy
- Control order is substitution, then wet cutting or water suppression, then local exhaust ventilation, with respiratory protection used only as the last line of defence.
- Scaffold guardrail heights
- Working platforms require guardrails at roughly one metre and half a metre above the deck, plus toe boards, full planking, and inspection tagging before each shift.
- Manual handling limit
- One person should not lift more than about twenty-five kilograms at waist height; heavier masonry units need two-person lifts or mechanical handling equipment.
- Mortar board care
- The board and hawk are cleaned after each batch. Hardened mortar is removed with water and a wire brush, never by striking the tool against finished masonry.
- Cement bag storage
- Bags are stacked on pallets, clear of the ground, under cover, and used oldest first. Damp storage causes lumping and loss of strength.
- Nominal versus actual block
- A nominal 200 mm hollow block measures about 190 mm actual width. The ten millimetre mortar joint completes the 200 mm module on the drawing.
- Drawing precedence rule
- Specifications govern general notes, and structural drawings govern member sizes. Any conflict between documents is raised as a written query before construction.
- Control dimension
- A written dimension on the drawing that governs setting out. Written dimensions are never scaled, and missing dimensions are never assumed.
- 3-4-5 right angle method
- Measure three units along one line and four along the other, then adjust until the diagonal reads five units. This produces a true right angle.
- Diagonal check rule
- Both diagonals of a rectangular setting out must be equal. A difference beyond about five millimetres over ten metres requires re-setting the corners.
- Story pole purpose
- A marked pole showing actual course heights including joints. It transfers course levels to the wall and keeps bed joints consistent over the full storey.
- Mortar type N proportion
- A general-purpose mortar mixed at one part cement, one part lime, and six parts sand by volume. It suits exposed above-grade loadbearing masonry.
- Mortar usable life
- Mixed mortar must be used within about one and a half hours in cool weather and one hour in hot weather, with retempering limited to one water addition.
- Sand bulking
- Moist sand occupies more volume than dry sand. Batch proportions measured by volume must allow for bulking so the cement-to-sand ratio stays correct.
- Bond offset rule
- Vertical joints in successive courses must be offset by at least one quarter of the unit length. Continuous vertical joints are not permitted in structural masonry.
- English bond pattern
- Alternating courses of headers and stretchers. It is strong and was traditional for thick walls, but the many headers make it slower to lay.
- Flemish bond pattern
- Each course alternates a stretcher and a header. It gives good appearance on both faces and ties the wall through the thickness in every course.
- Raking back a wall
- Leaving the end of a day's work as a stepped or toothed profile rather than a straight vertical joint, so the next lift bonds into it.
- Joint reinforcement placement
- Steel laid in the horizontal mortar bed at the vertical intervals shown on the structural drawings, typically every second course, with adequate mortar cover.
- Lintel bearing length
- The distance a lintel rests on masonry at each end, commonly one hundred to one hundred fifty millimetres, and never bearing over a hollow unit void.
- Wall tie function
- A metal tie connecting the two leaves of a cavity wall, spaced per specification and sloped slightly so water drains toward the outer leaf.
- Movement joint purpose
- A deliberate gap that lets masonry expand and contract without cracking. It is placed at changes in height, material junctions, and set intervals along long walls.
- Weathered joint profile
- A joint recessed at the bottom and sloping outward at the top, shedding water. It is formed by tooling when the mortar is thumb-print hard.
- Tooling versus striking
- Tooling compacts the mortar against the unit edges and improves weathertightness. A joint merely cut by the trowel is rougher and more permeable.
- Cold weather masonry rule
- Do not lay units on a frozen bed or with frozen materials. Finished masonry is protected from freezing until the mortar has gained sufficient strength.
- Settlement crack pattern
- Diagonal cracks, usually wider at one end and following joints or units, indicating differential movement of the foundation rather than shrinkage of the mortar.
- Repointing depth rule
- Old mortar is cut out to at least twice the joint width, with a ten millimetre minimum, then cleaned, wetted, and filled in compacted layers.
- Repair mortar compatibility
- Repair mortar should be weaker and more permeable than the original unit, so any movement or moisture damage occurs in the mortar rather than the masonry.
- Efflorescence treatment
- White salt deposits are removed by dry brushing and flushing with clean water. Recurrence signals an ongoing water source that must be corrected at its entry point.