Masonry NC II cheat sheet

A complete work instruction answers: what to build, where, to what dimension, with what material, by when, and who verifies it.

Verbal instructions must be confirmed by repeating them back to the speaker; unresolved differences are escalated in writing before work proceeds.

A bar chart or work schedule links each activity to a start date, finish date, predecessor, and crew size - use it to sequence masonry after structural framing and before finishing trades.

Standard hand signals for crane and hoist work: raised fist = stop, open palm up = hoist, open palm down = lower, arm extended and pointing = travel direction.

Daily site records (manpower, weather, work accomplished, deliveries received, instructions received) form the basis of progress claims and delay documentation.

A material requisition states unit, quantity, size, grade, and required delivery date; a delivery receipt is signed only after count and visual inspection.

Written change orders or site instructions must be signed and dated by the authorized representative before the affected work is executed.

Toolbox talks are logged with topic, date, attendees' signatures, and the hazard discussed; the log is the evidence of communication.

Personal protective equipment minimum on a masonry site: hard hat, safety footwear, eye protection, and gloves; add hearing protection near cutters and respirator when cutting silica-bearing units dry.

Fall protection is required at heights of 2 m or more, or where a fall hazard exists over openings, edges, or impalement hazards.

Scaffold rules: full planking, guardrails at approximately 1 m and 0.5 m, toe boards, stable footing, and inspection tagging before first use each shift.

Silica dust control hierarchy: substitution, wet cutting or water suppression, local exhaust ventilation, then respiratory protection as the last line.

Ladder setup: 4:1 slope for leaning ladders, extend 1 m above the landing, secure top and bottom, and maintain three points of contact.

Housekeeping rule: keep walkways and egress clear, remove offcuts and mortar spill at each shift end, and stack units at a stable height on level ground.

Manual handling limit for one person is roughly 25 kg at waist height; use two-person lifts, wheelbarrows, or mechanical hoists for heavier units.

Emergency response: know the assembly point, first-aid station, and the location of the nearest fire extinguisher and electrical disconnect before starting work.

Bricklayer's trowel sizes: 250-300 mm blade for general work; pointing trowel 150-200 mm for filling joints; margin trowel for tight areas.

Line and pins establish course alignment; a spirit level checks level and plumb, and a corner block or story pole transfers course heights.

A mason's line is stretched taut and checked at mid-span for sag; sag produces a bowed wall that fails the straightedge check.

Concrete mixer capacity is rated in drum volume; the batch must not exceed roughly 10 percent below the drum's rated capacity to allow proper tumbling.

Mortar board and hawk are kept clean; hardened mortar on tools is removed with water and a wire brush, never by striking against the wall.

Abrasive cutters for masonry units require water suppression or dust extraction, a full guard, and correct wheel rating for the machine's RPM.

Storage: cement bags on pallets, off the ground, under cover, and used oldest first; aggregate stockpiles separated by type and kept free of soil.

Inspection rule: tag out and remove from service any tool with a damaged cord, cracked handle, missing guard, or worn cutting wheel.

Drawing set order: title sheet, site plan, floor plans, elevations, sections, details, schedules, and structural drawings; the structural drawing governs member sizes.

Scale reading: verify the stated scale, then confirm a known dimension with a scale rule before taking off any measurement from the print.

A masonry unit schedule gives type, nominal dimensions, compressive strength, and joint thickness; the general notes give mortar class and reinforcement.

Nominal vs actual dimensions: a 200 mm concrete hollow block is nominally 200 mm wide but actual width is about 190 mm, with the 10 mm joint making up the module.

Section markers, detail callouts, and grid lines link plans to details; always trace a detail back to its location on the plan before building it.

Specifications override general notes when they conflict; where drawings and specifications conflict, raise a request for information before proceeding.

Symbol conventions: solid line = visible edge, dashed line = hidden or above, centerline = axis of symmetry, hatch = material type.

Control dimensions are the ones used for setting out; never scale a dimension that is written, and never assume a dimension that is missing.

Setting out sequence: establish the reference line or baseline from the site plan, then set corners by offset and diagonal check.

3-4-5 method: measure 3 units along one line and 4 along the perpendicular, and adjust until the diagonal reads 5 units - this produces a right angle.

Rectangular check: both diagonals of a rectangle must be equal; a difference of more than about 5 mm over a 10 m building requires re-setting.

Profile boards and batter boards are set back from the excavation edge so they survive digging; string lines between them mark wall faces and column centers.

The module of masonry is unit length plus joint thickness; course heights are set out from a story pole marked with the actual unit-plus-joint increments.

Level datum is transferred from a benchmark with a level or water level; all floor levels and finished floor heights reference the same datum.

Wall thickness set-out line: mark both faces of the wall, not just the centerline, so the mason can check thickness continuously.

Tolerances: plumb and level deviation is generally held within 10 mm over a storey height and 5 mm over 3 m of wall length unless the specification is stricter.

Mortar types by cement-to-lime-to-sand proportion by volume: Type M 1:1:6, Type S 1:1/2:4 1/2, Type N 1:1:6, Type O 1:2:9 - higher cement content gives higher strength.

Type N is the general-purpose mortar for exposed above-grade masonry; Type S is used where higher flexural or compressive strength is needed; Type M for severe exposure.

Water is added to reach a workable consistency, roughly a slump of 100-150 mm on a flow test; too much water reduces strength and increases shrinkage.

Mortar must be used within about 1.5 hours of mixing in cool weather and 1 hour in hot weather; retempering with water is limited to one addition.

Batch measurement is by volume with a consistent gauge box; the sand must be measured damp and allowance made for bulking of moist sand.

Sand for mortar is clean, well graded, and free of organic matter and clay lumps; a dirty sand raises water demand and lowers strength.

Mixer sequence: add part of the water, then sand and cementitious materials, then the balance of water; mix 3-5 minutes after all materials are in.

Mortar joints are typically 10 mm thick; joints thinner than about 6 mm or thicker than about 13 mm reduce bond and compressive strength.

Bond rules: vertical joints in successive courses must be offset by at least one-quarter of the unit length; continuous vertical joints are prohibited.

Running or stretcher bond offsets each course by half a unit; header bond uses headers to tie two leaves; English bond alternates header and stretcher courses; Flemish bond alternates stretcher and header in the same course.

Full bed and full head joints are required; a face-shell-bedded hollow block wall relies on the shell area and is specified only for non-structural or low-load walls.

Frog-up versus frog-down: solid units are laid with the frog upward unless the specification states otherwise; hollow units are laid with the larger face up.

Course height control uses a story pole and line; the line is moved up every course and checked for level at both ends and mid-span.

Units are laid with a slight tapping motion to set the joint, never by sliding, which smears mortar and breaks bond.

Toothing and racking: a wall left for the day is stepped or raked back, not left as a straight vertical joint, so the next lift can bond into it.

Hollow unit walls are laid from the corners, with the first course set on a full mortar bed and checked for level and square before continuing.

Horizontal joint reinforcement is laid in the mortar bed at specified vertical intervals, typically every second course or as shown on the structural drawings.

Reinforcement must be embedded with adequate cover; mortar cover to steel in exposed masonry is generally at least 15-20 mm.

Grout for reinforced hollow masonry is a high-slump mix placed in lifts; lifts are limited in height and consolidated to avoid voids around the steel.

Lintels span openings and must bear on the wall at each end by the specified bearing length, commonly 100-150 mm, and never bear on a hollow unit's void.

Wall ties connect leaves of a cavity wall; they are spaced per specification and sloped slightly to shed water toward the outer leaf.

Anchors into concrete or masonry are selected by load type (tension, shear, combined), base material, and edge distance; expansion, adhesive, and screw anchors behave differently.

Movement joints accommodate expansion and contraction; they are located at changes in height, at junctions with other materials, and at specified intervals along long walls.

Beams, columns, and bond beams are cast or placed in the sequence shown on structural drawings; masonry is not loaded by a member until the member has reached adequate strength.

Joint finishes: flush, weathered (recessed at the bottom), struck or keyed, and raked; the specified profile is applied when the mortar is thumb-print hard.

Tooling compacts the mortar at the joint face and improves weathertightness; a joint left as cut by the trowel is more permeable.

Curing keeps moisture in the mortar; masonry is protected from rapid drying by wind and sun for at least the first 24-72 hours depending on specification.

Hot-weather precautions: shade the materials, use cooler water, keep units damp, and avoid laying on a hot dry surface that pulls water from the mortar.

Cold-weather rule: protect masonry from freezing until the mortar has gained strength; do not lay on a frozen bed or with frozen materials.

Quality checks: plumb with a level or plumb bob, level with a spirit level, straightness with a straightedge and line, and joint thickness with a rule at several points.

Compressive strength acceptance is by sampling mortar or masonry prisms per the specification; results are compared with the specified class.

Acceptance criteria for finished walls include alignment within tolerance, full joints, correct bond pattern, clean face, and no unplanned shrinkage cracks.

Diagnose before repairing: distinguish settlement cracks (diagonal, wider at one end) from shrinkage cracks (uniform, often at joints) and from thermal movement cracks.

Crack repair: clean the crack, wet the surface, and fill with a compatible mortar or sealant; movement cracks use a flexible sealant, not rigid mortar.

Repointing sequence: cut out the old mortar to a depth of at least twice the joint width (minimum 10 mm), clean, wet, and fill in compacted layers.

Repair mortar must be compatible with the original - usually weaker and more permeable than the unit, so the mortar fails before the masonry does.

Efflorescence is removed by dry brushing and flushing with clean water; persistent recurrence indicates a water source that must be corrected.

Spalling and delamination are often caused by moisture ingress and salt crystallization; repair requires correcting the water path, not just patching the face.

Replacement of units: remove the damaged unit without loading the wall above, clean the pocket, and re-bed the new unit with full mortar contact.

Maintenance schedule: inspect joints, flashings, weepholes, and movement joints after each rainy season and record defects with location and extent.