Intermediate Scaffolding (SI) key terms

A person who has the training, qualification and practical experience needed to carry out a scaffolding task safely, and who can recognise defects and unsafe conditions in the work.

A competent person appointed to examine a scaffold at required intervals and after events such as high winds or impact, recording the findings and tagging the scaffold with its status.

A formal authorisation, issued under the applicable national or regional scheme, permitting a person to erect, alter or dismantle scaffolding above a defined height once competence has been assessed.

A scaffold of a size or type that regulations require to be reported to the work-safety authority before work starts, typically using a written notification form with site and constructor details.

A written record, signed after inspection, confirming a completed scaffold is fit for the intended use and stating its duty rating, height, date of inspection and any restrictions on use.

A durable sign fixed at the access point showing whether the scaffold is safe to use, who inspected it, when it was inspected and what load limit applies.

The load classification assigned to a scaffold that states the maximum uniformly distributed and concentrated loads it may carry, and therefore which trades and materials may use it.

The permanent weight a scaffold must carry from its own components, such as standards, ledgers, boards and fixed attachments, calculated before any workers or materials are added.

The variable weight placed on a scaffold during use, including workers, tools, stacked materials and waste, which changes through the day and must stay within the duty rating.

A concentrated force applied to a small area of a scaffold, such as a stack of bricks or a single foot, which can overstress a board or beam even when total weight seems acceptable.

Distributing weight over a wider area using sole boards, spreader beams or extra transoms so that no single component, board or footing is overloaded.

A thick timber or purpose-made pad placed under a base plate to spread the scaffold's leg load over a larger ground area and prevent settlement or punching into soft surfaces.

A steel plate fixed to the bottom of a standard to spread its load onto the sole board and to locate the leg positively, often with an adjustable jack for levelling.

The maximum pressure the ground beneath a scaffold can support without excessive settlement, shear failure or collapse, assessed before any legs are set down.

The check for buried pipes, cables, drains and voids before scaffold legs or ties are placed, so that loads are not imposed on or damage hidden services.

The vertical tube of a scaffold that carries load down to the ground or supporting structure and to which ledgers, transoms and braces are connected.

A horizontal tube running along the length of a scaffold, parallel to the face, that ties standards together and supports transoms and working platforms.

A horizontal tube running across the width of a scaffold, at right angles to the ledgers, that supports the working platform and connects the inner and outer standards.

A diagonal tube fixed across a frame of standards and ledgers or transoms to give the scaffold stiffness and resist sway, wind and racking forces.

A fixing that anchors the scaffold to a building or structure to resist wind uplift, overturning and lateral movement, usually a through-tie or a drilled anchor with a tie tube.

The planned arrangement of ties, such as every lift and bay or a staggered pattern, set by the design or manufacturer's guidance to keep the scaffold stable at all stages.

Distortion of a scaffold frame under lateral force, where the rectangular frames lean into a parallelogram shape; braces and ties are provided to prevent it.

The boarded level of a scaffold from which work is done, which must be fully decked, closely boarded or boarded with controlled gaps and fitted with guard rails and toe boards.

An upper and intermediate horizontal rail fitted at the edge of a working platform to stop people falling, set at the specified heights above the platform surface.

A low upstand fixed along the edge of a working platform that prevents tools, materials and waste from being kicked or blown off the scaffold onto people below.

Personal equipment, such as a full-body harness and lanyard attached to a suitable anchor, that stops a falling worker and limits the distance and force of the fall.

A structural fixing of proven strength to which a lanyard or lifeline is attached; on scaffolds it must be independent of the scaffold unless the scaffold is designed for it.

A prepared procedure for recovering a worker quickly after a fall or suspension, naming equipment, trained rescuers and the steps to take before emergency services arrive.

Serious illness caused by blood pooling when a person hangs motionless in a harness, which can develop within minutes and requires fast rescue and medical attention.

A marked and controlled area beneath and around scaffolding work where only authorised people may enter, keeping others clear of falling objects and unstable structures.

A purpose-made net rigged below a work area to catch falling people or debris, installed by trained riggers with correct anchorage and inspected before each use.

A short briefing given before work starts that covers the task, the hazards, the control measures and each person's role, with understanding confirmed by the supervisor.

A written description of how a scaffold task will be carried out safely, listing the sequence of work, plant, controls, responsibilities and emergency arrangements.

A structured review that identifies hazards in the scaffold task, judges who might be harmed and how, and records the controls needed to reduce risk to an acceptable level.

The order in which controls are chosen, from eliminating the hazard and using engineering measures down to administrative controls and personal protective equipment as the last resort.

A formal written authorisation required before specified high-risk tasks, stating the work, its limits, the precautions taken and the person who authorised it.

A procedure for isolating energy sources such as electricity or moving plant, applying a personal lock and warning tag so equipment cannot be re-energised during scaffold work.

An energised cable above the site; scaffolds must keep the mandated clearance from it, with goalposts and warning signs where plant or workers could encroach.

The ability of a scaffold to resist overturning, sliding and sway under its own weight, imposed loads and wind, achieved through ties, braces, correct footings and geometry.