Stability and Outriggers Flashcards

What is 'kentledge' in the context of tower scaffold stability?

Answer: Counterweights (usually concrete or steel blocks) placed at the base to resist overturning forces

Kentledge consists of heavy weights (concrete blocks, steel plates, or sandbags) secured at the base of the tower to increase the downward force and restoring moment. It must be placed as specified by the manufacturer and securely fixed to prevent displacement.

Can a tower scaffold be tied to a vehicle for additional stability?

Answer: No — a vehicle could move, be driven away, or bounce on its suspension, compromising the tower

Tying a tower to a vehicle is not an acceptable means of stabilisation. Vehicles can be inadvertently driven away, bounce on their suspension, or settle on their tyres, all of which could destabilise the tower. Only fixed structures should be used for tying.

What is the effect of removing braces from a fully assembled tower to allow better access or working?

Answer: It severely compromises the structural integrity and racking resistance, and the tower may collapse

Braces are critical structural members that provide racking resistance and maintain the tower's geometry. Removing any brace dramatically reduces the tower's strength and can lead to immediate collapse, especially under load or wind.

What precaution should be taken when using a tower scaffold on a suspended floor (e.g., upper storey)?

Answer: The floor's load-bearing capacity must be verified to ensure it can support the total weight of the tower, occupants, and materials

Suspended floors have load limits that can be exceeded by the concentrated load of a tower scaffold. A structural assessment must confirm the floor can support the combined weight. Point loads through castors or base plates can be particularly problematic.

What is the minimum distance outriggers should extend from the tower base?

Answer: As specified in the manufacturer's instruction manual for the specific tower height and configuration

The required outrigger extension depends on the specific tower system, its height, and configuration. The manufacturer's instruction manual specifies the exact deployment dimensions. Using shorter outrigger extensions than specified renders them ineffective.

How should the ground beneath outrigger base plates be assessed?

Answer: By checking that the ground is firm, stable, level, and capable of supporting the concentrated load without settling

Each outrigger base plate location must be assessed for ground firmness and stability. The ground must support the concentrated load without settling. On soft ground, sole boards must be used. On slopes, the outriggers may need adjustment.