CITB Specialists Temporary Works and Scaffolding 2 — Questions and Answers
Question 1: What are the requirements for edge protection on a scaffold working platform used by specialist trades at height?
- A single guardrail at any convenient height
- A top guardrail at minimum 950mm, a mid-rail, and a toe board at least 150mm high at every open edge (Correct answer)
- Guardrails are optional if workers wear harnesses
- Netting on the outside of the scaffold is sufficient
Correct answer: A top guardrail at minimum 950mm, a mid-rail, and a toe board at least 150mm high at every open edge
The Work at Height Regulations 2005 and NASC guidance require scaffold platforms to have a top guardrail at a minimum height of 950mm above the platform, a mid-rail to prevent anyone falling through the gap, and a toe board at least 150mm high to prevent materials being kicked off the edge. All three elements are mandatory at every unprotected edge.
Question 2: A specialist contractor needs to erect a scaffold over a public footpath. What additional measures are required under UK regulations?
- Place warning signs and continue
- A gantry or protected walkway with overhead protection, lighting, and a licence from the local authority (Correct answer)
- Barrier tape across the footpath to divert pedestrians
- High-visibility cladding on the scaffold
Correct answer: A gantry or protected walkway with overhead protection, lighting, and a licence from the local authority
Scaffolds over public footpaths require a pedestrian gantry providing a minimum headroom (typically 2.4m), overhead protection (fans or boards) to prevent falling objects, adequate lighting, and a scaffold licence from the local authority. The gantry must be designed to carry imposed loads and be regularly inspected.
Question 3: When specialist scaffolding is erected in a location exposed to high winds, what additional design consideration must be applied?
- Use heavier scaffold tubes
- A wind loading assessment must be carried out, and the scaffold designed to resist the calculated wind forces, with additional ties and bracing as required (Correct answer)
- Add extra scaffold boards to weigh it down
- Only erect the scaffold during calm weather
Correct answer: A wind loading assessment must be carried out, and the scaffold designed to resist the calculated wind forces, with additional ties and bracing as required
Wind loading is often the most significant force acting on a scaffold. A wind loading assessment (per TG20 or bespoke design) must calculate the forces based on location, height, topography, and whether the scaffold is sheeted or netted. Additional ties, bracing, and foundation loads are specified to resist these forces. Sheeted scaffolds attract significantly greater wind loads.
Question 4: What is a 'design check category' in relation to specialist temporary works under BS 5975?
- A quality grading for scaffold tubes
- A classification (1, 2, or 3) that determines the level of independent design checking required based on the complexity and risk of the temporary works (Correct answer)
- A fire rating for temporary structures
- A cost category for budgeting purposes
Correct answer: A classification (1, 2, or 3) that determines the level of independent design checking required based on the complexity and risk of the temporary works
BS 5975 categorises temporary works into three design check categories based on risk and complexity. Category 1 requires a self-check by the designer, Category 2 requires an independent check by another competent person, and Category 3 (highest risk, such as large falsework or complex temporary structures) requires checking by an independent checking organisation.
Question 5: A specialist scaffolder discovers that a scaffold standard (vertical tube) is resting on soft ground that is beginning to sink. What is the correct action?
- Pack materials under the base plate to level it
- Stop work, evacuate the scaffold, report to the scaffold supervisor and TWC for an engineered solution such as sole boards or foundations (Correct answer)
- Adjust the jack and continue working
- Move the standard to a firmer location
Correct answer: Stop work, evacuate the scaffold, report to the scaffold supervisor and TWC for an engineered solution such as sole boards or foundations
Settlement of scaffold foundations is a serious structural issue that can lead to progressive collapse. The scaffold must be evacuated and tagged as unsafe. The TWC and scaffold supervisor must assess the situation and implement an engineered solution — typically sole boards of adequate size to distribute the load, or concrete pads for heavy-duty scaffolds.
Question 6: What is the minimum width of a scaffold working platform for specialist construction work where materials need to be stored on the platform?
- 600mm (3 boards)
- 800mm (4 boards)
- A minimum of 5 boards wide (1.07m) to allow safe passage while materials are stored (Correct answer)
- Any width as long as guardrails are fitted
Correct answer: A minimum of 5 boards wide (1.07m) to allow safe passage while materials are stored
Where materials need to be stored or stacked on a scaffold platform, the minimum width must allow at least 600mm clear passageway alongside the stored materials. In practice, this means a platform of at least 5 boards (approximately 1.07m) or wider. NASC TG20 provides specific width requirements based on the intended use of the platform.
CITB Specialists Temporary Works and Scaffolding 2
What are the requirements for edge protection on a scaffold working platform used by specialist trades at height?