Why it matters

A scaffold is a temporary structure carrying people and loads. When it fails, it fails all at once. Workers fall, and materials drop on the people below.

Most scaffold incidents trace back to a few causes. Someone removed a tie, a brace or a board. Someone overloaded a bay. A worker climbed the frame because the ladder was at the far end. All of these can be seen on a walk round.

You do not need to be an engineer to spot them. You need to know what a safe scaffold looks like and refuse to let anyone use one that is not.

Who may erect and alter a scaffold

In Singapore, only an approved scaffold contractor may erect, alter, move, repair or dismantle most scaffolds. The rule covers any scaffold 4 metres or taller, measured without the top handrails. It also covers every suspended or hanging scaffold, and any scaffold on cantilever or jib supports, whatever the height.

Tower scaffolds and trestle scaffolds are excluded from the contractor rule. They still need trained erectors and a scaffold supervisor.

Every erector must have passed an approved scaffold erector course. A trained scaffold supervisor must be appointed before work starts and must directly supervise all erection and dismantling. Erectors wear a harness with a shock absorber, clipped to an independent lifeline or other secure anchor.

Order of controls

A scaffold is itself a control for work at height. Even so, ask the higher questions first.

  • Eliminate. Can the work be done from the ground or from a permanent floor?
  • Substitute. For short, light work, a MEWP or tower scaffold may carry less risk than a full scaffold.
  • Engineer. Design the scaffold for the load. Fit full guard-rails, toe-boards, ties, bracing, stair or ladder access inside the scaffold, and screening nets.
  • Administer. Inspections, labels, load signs, exclusion zones below, and a ban on altering the scaffold.
  • Personal protection. Harnesses for erectors and wherever edge protection is incomplete.

What a safe scaffold looks like

Start at the bottom. The scaffold must stand on firm, consolidated ground or a structure strong enough to carry it. Base plates sit on sole plates. There must be no hollow under a sole plate below a standard.

Look up. Standards should be plumb. On metal scaffolds they must be no more than 2.5 metres apart unless MOM has approved otherwise. Bracing and ties must be complete. Never let anyone use a cross brace as a ladder.

  • Work platforms at least 500 mm wide, fully boarded, with no gaps except for access.
  • No more than 300 mm between the platform and the building face.
  • Toe-boards at least 90 mm high and two or more guard-rails on any side with a fall of more than 2 metres.
  • Top guard-rail at least 1 metre above the platform; no gap over 600 mm between rails.
  • Stairs or ladders between levels, inside the scaffold where reasonably practicable.
  • At least one marked access point, made safe for use.
  • Screening nets on timber or metal scaffolds built on the outside of a building.

Loading

Overloading is a quiet killer. Workers stack bricks or tiles on one bay because it is close to the job. The scaffold was not designed for it.

Signboards on the scaffold must show the maximum weight of tools and materials and the maximum number of people per bay. They stay up until the scaffold comes down. Spread loads evenly. Lower materials onto the platform gently, never drop them.

Load limits in the regulations

On a metal scaffold, the platform load in any bay must not exceed 220 kgf per square metre. No more than 4 persons may stand on one platform in a bay, and no more than 8 persons may be in the whole bay. A professional engineer must design the platform if it carries more than 2 persons or over 25 kgf of tools or materials per bay. Check your scaffold design drawings, which may set lower limits.

Inspection and tagging

The scaffold supervisor inspects the scaffold when erection is complete. After that, the supervisor checks it at least once every 7 days. The scaffold also needs a check after weather that could have weakened it or shifted any part.

Each inspection goes into a register, which the occupier keeps on site for inspectors. Straight after each check, the supervisor puts a notice or label at every access point. It must say clearly whether the scaffold is safe to use. Many sites use a green tag for safe and a red tag for do not use.

Workers may not use a scaffold unless that safe label is in place. A part-built or part-dismantled scaffold must be made safe or carry a prominent do-not-use warning.

Tower and mobile scaffolds

Tower scaffolds are easy to put up and easy to topple. Height is limited to 8 times the shortest base side, or 4 times on board a ship. Above 3 times the shortest base side, the tower must be tied to the building or a rigid structure.

Mobile towers need a positive lock on every caster and a firm, level floor. Push the tower at the base only. Nobody stays on it while it moves. Lock the casters before anyone climbs. Only two working platforms may be in use at one time.

What the rules require (Singapore)

The law is the Workplace Safety and Health (Scaffolds) Regulations 2011. The Code of Practice for Working Safely at Heights also covers scaffolds.

  • Approved scaffold contractor for scaffolds 4 m and above, and all suspended, hanging and cantilever scaffolds (reg 4).
  • Trained erectors and a trained, appointed scaffold supervisor; erection only under the supervisor's direct supervision (regs 5, 6 and 8).
  • Harness with shock absorber and secure anchorage for erectors (reg 7).
  • Designated, marked access point (reg 12); stairs or ladders between levels (reg 13).
  • Platform width, gaps, guard-rails and toe-boards (regs 18 and 22).
  • Load signboards and limits (regs 19 and 20).
  • Inspection by a scaffold supervisor on completion, every 7 days and after bad weather, with a register (reg 26).
  • Safe or unsafe label at every access point; no use without a safe label (reg 27).
  • No cross brace used for access on frame scaffolds (reg 36); tower scaffold limits (reg 51).

Common mistakes

  • Trades removing a tie, brace or guard-rail to get their work done, then leaving it off.
  • Climbing the outside of the frame instead of walking to the access point.
  • Stacking materials in one bay well past the posted limit.
  • An inspection tag that is weeks out of date, or a tag on one access point but not the others.
  • Moving a mobile tower with a worker still on the platform.
  • Planks resting on a gutter, an unsecured brick or a loose sole plate.
Only the scaffold crew alters the scaffold

If a trade needs a board or rail moved, they ask. The scaffold supervisor arranges the change and re-inspects. Nobody else touches the scaffold.

In other countries

  • Indonesia: Permenaker No. 9 of 2016 requires employers to make sure work at height on scaffolds and ladders meets K3 safety requirements set by other laws. Workers on scaffolds are covered by separate rules. Source: Permenaker 9/2016 (BPK database).

Use it on site: the scaffolding checklist and the toolbox talk to brief your crew.

Sources

  1. Workplace Safety and Health (Scaffolds) Regulations 2011, Singapore Statutes Online (AGC).
  2. Code of Practice for Working Safely at Heights, WSH Council.
  3. Code of practice on safety and health in construction (revised 2022), International Labour Organization.
  4. Permenaker No. 9 Tahun 2016 tentang K3 dalam Pekerjaan pada Ketinggian, Kemnaker (via BPK JDIH).

This is practical guidance, not legal advice. Laws and codes of practice change; always check the current official text and your site's own procedures.