Scaffolding Terminology, Components, and Systems
Core vocabulary
A scaffold is a temporary working platform, and precise terms separate a safe structure from a hazard. The standards (posts) are the vertical members; ledgers run horizontally parallel to the wall; transoms run perpendicular to the wall and carry the platform; putlogs are a type of transom that also bears on the wall. Base plates distribute load to sills or the ground, and sole boards/sills spread load across soft surfaces. Braces include ledger (horizontal), facade, and end (transverse) braces, plus plan bracing in tube-and-fitting systems. Ties anchor the scaffold to the structure; couplers join tubes; reveal ties, box ties, and through ties differ in how they grip the building.
Systems
Recognize tube-and-fitting (universal), modular/system (cuplock, ringlock, kwikstage), frame (mason's frames with cross braces), mobile/tower scaffolds, and suspended or cantilever scaffolds. Each has distinct component names and capacities; exam questions often swap a frame cross-brace for a facade brace, or call a putlog a ledger.
Common traps
- Confusing ledgers (horizontal, along the face) with transoms (across the width).
- Believing a putlog is a brace; it is a load-bearing transom in putlog scaffolds.
- Assuming all couplers are interchangeable - right-angle, swivel, and sleeve couplers do different jobs.
- Forgetting that guardrails (top and intermediate) and toe boards are separate from the working platform.
Rule of thumb
Along a bay, the working platform sits on transoms spaced at the bay length; ledgers tie standards together at lift heights. If a member runs parallel to the wall, think ledger; if it crosses the scaffold to the wall, think transom.
Worked example
A candidate sees a horizontal tube fixed along the outside face connecting three standards at 2 m height. That is a ledger, not a guardrail - guardrails sit at the platform edge, typically at about 950 mm and 470 mm above the platform.