The purpose of ties is to restrain the scaffolding standards in a vertical position so they can carry the weight of the structure, the boards, personnel and materials without buckling.
During its operational lifetime, a scaffold may be subjected to high winds that will attempt to push it towards the building, pull it away or move it parallel depending on which way the wind is blowing.
The ties that are required to stabilise a scaffold depend on
• It’s height
• The exposure to wind
• Whether it is sheeted or debris netted
• The extent to which it is shielded against the wind
The tie values can be found on either your compliance sheet or design drawing
The tie duty, is the tension load each tie must resist to prevent the scaffolding from moving. It will also determine which type of tie to use and their required strength. The strength of the tie is known as the safe working load
Proof testing should be 1.25 x the working allowance load e.g. 6.1 Kn ( general purpose)
= proof test of 7.6Kn
A minimum of 3 ties must be tested and ideally around 5% of the total job ( 1 in 20)
Tie arrangements – according to TG20:13, compliance sheets they will specify the tie pattern required to distribute the ties evenly throughout the scaffold. this includes
• The tie frequency
• The maximum vertical spacing between rows of ties
• The maximum horizontal spacing’s between columns of ties
ALWAYS MAKE SURE YOU FOLLOW THE TIE REQUIREMENTS THAT ARE STATED ON YOUR DESIGN OR COMPLIANCE SHEET – THE METHOD, THE TYPE AND THE ARRANGEMENTS
ALWAYS ENSURE THE TIES ARE TESTED CORRECTLY BY A COMPETENT PERSON UTILISING A CALIBRATED TESTER
TOO OFTEN WE SEE SCAFFOLD COLLAPSES IN THE NEWS.
THESE CAN BE AVOIDED IF YOU TIE YOUR SCAFFOLDING IN CORRECTLY AND AS PER DESIGN OR COMPLIANCE SHEET