Advanced Scaffolding (SA) cheat sheet

Design load classes: light duty 2.0 kN/m² (≈225 kg/m²), medium duty 2.5 kN/m², heavy duty 3.0 kN/m²; never mix classes on one working platform without re-rating the whole run.

Ground bearing pressure = total leg load ÷ effective base plate area; a 150 mm × 150 mm base plate gives 0.0225 m², so a 10 kN leg load produces ≈444 kPa - verify against soil allowable bearing capacity.

Minimum clear access width for a working platform is 600 mm; two-board (450 mm) platforms are for access only, not work.

Scaffold must be at least 3.5 m horizontally from any overhead power line up to 66 kV; higher voltages require utility coordination and a written permit.

Falls of 2 m or more, or any fall onto a hazardous surface, trigger fall protection; guardrail top rail 950–1100 mm, mid-rail at approximately half height, toe board ≥150 mm.

Public protection: fan (debris) netting or a protected walkway is required wherever material could fall onto a pedestrian route; the exclusion zone width equals the height of the scaffold plus the fall radius of dropped material.

Site survey must record slope, drainage, buried services, adjacent excavations, and the setback from the excavation crest - the setback should be at least equal to the excavation depth unless a geotechnical assessment permits less.

Planning documents: a scaffold design or standard-tower selection sheet, a load rating, an erection sequence, and a rescue plan for suspended or fall-arrest situations.

Bay length to height ratio: independent tied scaffolds generally need ties at vertical intervals ≤ 4 m and horizontal intervals ≤ 6 m for standard configurations; ties resist wind uplift and pull-off, not just compression.

Load path: platform load → transoms → ledgers → standards → base plates → ground; any break in this chain (missing transom, unbraced standard) creates a concentrated overload.

Bracing rules of thumb: ledger bracing (zig-zag) on every alternate bay and at both ends; facade bracing continuous to the top; and a longitudinal bracing bay at no more than 30 m centres.

Wind load on open scaffold ≈ 0.7 × q × A for tubes (drag coefficient), so netting or sheeting can multiply wind force several times - recalculate ties and anchors before adding any sheet.

Standard tube: 48.3 mm outside diameter, 3.2 mm nominal wall (4.0 mm for heavier duty), yield strength 235–355 MPa; do not mix tube diameters or coupler types in one member.

Right-angle couplers carry slip capacity of roughly 6–7 kN per bolt when correctly torqued to 40–50 N·m; swivel couplers are lower and must never be the sole connection for a load-bearing tie.

Suspended and cantilever scaffolds: the design moment at the anchorage equals the suspended load times its lever arm plus self-weight; counterweights must be fixed (not loose) and calculated, not estimated.

Stability: the scaffold's resistance to overturning is provided by ties and bracing; free-standing towers are limited to a base-to-height ratio of about 1:3 (1:4 with outriggers).

Erection proceeds bottom-up in complete lifts: base, standards, ledgers, transoms, then platform, then guardrails - never leave a lift without its guardrails before the next lift is started.

Ties must be installed progressively as the scaffold rises; a scaffold more than 2 m above a tie level without ties is not permitted to remain standing overnight without a documented assessment.

Dismantling is the reverse of erection: remove top-down, keep ties in place until the lift below is removed, and never drop or throw tubes - use a gin wheel or chute.

Competent-person rule: erection, alteration, and dismantling require a person trained and assessed for the specific scaffold type; alteration by untrained users (e.g., removing a guardrail) is the leading cause of scaffold incidents.

Gin wheel capacity is typically 250 kg with a 500 kg SWL rope; never exceed the rated capacity and always secure the wheel to a standard with a positive fixing, not a single coupler.

Ladder access: stiles extend 1 m above the landing, ladder angle 75° (1 in 4), and a ladder must be tied at intervals of no more than 9 m.

Before any alteration, the change must be assessed against the original design; adding a platform level, a sheet, or a hoist changes the load path and requires re-verification.

Weather hold points: stop erection or dismantling when wind exceeds the manufacturer's limit (commonly 17 m/s or 38 mph for sheeted scaffolds), in lightning, or when ice forms on tube surfaces.

Inspection frequency: before first use, after any alteration, after any event likely to affect stability (impact, storm, overload), and at least every 7 days while in use.

Inspection record must list: date, time, scaffold location, load class, findings, corrective action, and the inspector's name and signature; retain records for the life of the scaffold plus the statutory period.

Defect grading: red tag (do not use) for missing ties, guardrails, or base plates; amber tag (restricted use) for minor damage; green tag (safe) only after a full check.

Load limits: never exceed the rated duty class; point loads (e.g., a stack of bricks) must be spread over at least two boards or a load-spreading plate.

Maintenance: inspect tubes for bends over 5 mm per metre, cracks, and corrosion loss over 10% of wall thickness; discard damaged components rather than repair them.

Fall protection during inspection: use the same fall-arrest system as erection; a scaffold is not a fall-protection system for the people inspecting it.

Emergency plan: rescue of a suspended worker must be achievable within 15 minutes; a fall-arrest harness causes suspension trauma, so prompt rescue is a life-safety requirement, not a nicety.

Housekeeping: no loose material on platforms, no overlapping boards without a positive fixing, and no accumulation of debris that can blow off or overload the platform.