Tie Pattern Dispute on a 24 m Scaffold
A 24 m high independent scaffold is erected along a building facade. The design drawing specifies ties at every lift and every 4 m horizontally. The site foreman, under schedule pressure, instructs the crew to install ties only at every second lift and every 6 m horizontally, arguing that the scaffold 'feels solid' and that the building's cladding prevents fixing at the specified locations. The crew has completed 18 m of height with the reduced tie pattern. The wind is forecast to increase to 40 km/h overnight. The scaffold is not yet loaded with materials. The design engineer is unavailable until the next morning.
1. What should the competent person do immediately, and why?
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The competent person must stop work and prevent any further erection until the tie pattern is corrected to the design. The reduced tie pattern (every second lift and 6 m spacing) significantly lowers the scaffold's resistance to wind and eccentric loads. With 18 m of scaffold erected and wind forecast at 40 km/h, the risk of overturning or racking is real. The competent person should: (1) instruct the crew to cease work and clear the scaffold of loose materials; (2) assess whether temporary additional ties or guys can be installed safely before nightfall; (3) if not, consider partial dismantling to a height that is stable with the existing ties, or install temporary ground anchors; (4) notify the site manager and design engineer; (5) record the event in the scaffold register. The foreman's argument that the scaffold 'feels solid' is not an engineering justification; ties are structural elements, not optional.
2. How should the competent person address the cladding obstruction?
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The cladding prevents fixing ties at the specified locations, but that does not justify omitting them. The competent person should explore alternative tie methods that maintain the design intent: (1) use through-ties with suitable spreader plates if the cladding can be temporarily removed or if there are structural members behind; (2) use reveal ties or box ties that engage the window openings; (3) if the cladding is non-structural, use chemical anchors into the structural wall behind, with the engineer's approval; (4) if none of these are feasible, the design must be revised by the engineer to account for the actual tie positions, possibly requiring additional standards or larger sections. The competent person should not proceed without a revised design. The correct action is to escalate to the engineer and, in the interim, keep the scaffold unloaded and restrict access.