TWK/Specific/TBT-TWK-010

Kentledge and Counterweight Systems

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Kentledge uses heavy blocks or weights to provide counterbalance or downward force for temporary works.
Common applications include anchoring formwork, stabilising crane bases, and weighting cofferdam structures.
Kentledge blocks typically weigh 500kg to several tonnes each and require crane handling for placement.
The temporary works design must specify the exact weight, position, and stacking arrangement of kentledge.
Incorrectly positioned or insufficient kentledge allows the structure to lift, slide, or overturn.
Stacked kentledge blocks can topple if not placed on level surfaces with interlocking arrangements.
The ground beneath kentledge must be assessed for bearing capacity to prevent settlement and tilting.
Removal of kentledge must follow the designed sequence; premature removal causes structural instability.
Kentledge is a temporary works scheme requiring TWC approval, design check, and register entry.
LOLER 1998 applies to all lifting operations involved in placing and removing kentledge blocks.

Structural failure	Insufficient or misplaced kentledge allows temporary works to lift or overturn, causing collapse and crushing.
Toppling blocks	Stacked kentledge blocks weighing tonnes topple from unstable arrangements, crushing workers beneath.
Design critical	Kentledge weight and position are engineered values. Guesswork or approximation leads to structural failure.

Don't

Follow the temporary works design for kentledge weight, position, and stacking.
Assess ground bearing capacity before placing kentledge at any location.
Use a lift plan for placing and removing kentledge blocks with the crane.
Stack blocks on level surfaces using interlocking arrangements to prevent toppling.
Register the kentledge scheme in the temporary works register with TWC approval.
Establish exclusion zones during kentledge placement and removal crane operations.
Inspect kentledge position and stability regularly during the temporary works period.
Remove kentledge in the sequence specified by the temporary works design.
Verify the total weight placed matches the design requirement before loading the structure.
Brief the team on the kentledge layout and the importance of maintaining positions.

DON'T use less kentledge than the temporary works design specifies.
DON'T position kentledge in locations different from those shown on the design.
DON'T stack blocks on soft or uneven ground without checking bearing capacity.
DON'T remove kentledge before the TWC authorises removal in the designed sequence.
DON'T stand under kentledge blocks being lifted, placed, or adjusted by crane.
DON'T stack blocks in unstable arrangements without interlocking or restraint.
DON'T guess the weight needed; use only the amount specified in the design.
DON'T use kentledge without registering it as a temporary works scheme.
DON'T allow other trades to move or remove kentledge blocks from position.
DON'T substitute different block types without checking the weight matches the design.

See also: Temporary Works Awareness | Temporary Works Inspection Requirements

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