The main elements of a scaffold are poles called scaffolding standards, scaffolding ledgers and scaffolding transoms.
Scaffolding Standards
Scaffolding Standards, also called uprights, are the vertical tubes that transfer the entire mass of the structure to the ground where they rest on a square scaffolding base plate to spread the load. At the centre of the base plate is a shank to hold the tube which is sometimes pinned to a scaffolding sole board to help distribute the weight.
Ledgers are horizontal tubes which connect between the standards stabilising the structure.
Scaffolding Transom
Transoms rest upon the ledgers at right angles forming a much more rigid structure. Main scaffolding transoms are placed next to the standards, they hold the standards in place and provide support for boards; intermediate scaffolding transoms are those placed between the main scaffolding transoms to provide extra support for scaffolding boards.
Scaffolding Cross Braces
Scaffolding cross braces are a further brace fitted to the scaffolding standards to increase rigidity, these are placed diagonally from ledger to ledger. If the scaffolding braces are fitted to the scaffolding ledgers they are called gin wheels. To limit sway a facade brace is fitted to the face of the scaffold every 30 metres or so at an angle of 35°-55° running right from the base to the top of the scaffold and fixed at every level.
Right angle coupler
Right-angle couplers join ledgers or transoms to standards, putlog or single couplers join board bearing transoms to ledgers – Non-board bearing transoms should be fixed using a right-angle coupler. To connect tubes at any other angle scaffolding swivel couplers are used. The actual joints are staggered to avoid occurring at the same level in neighbouring standards.
The spacing of the basic elements in the scaffold is fairly standard. For a general purpose scaffold the maximum bay length is 2.1 m, for heavier work, where the structure has to carry a greater load, the bay size is reduced to 2 or even 1.8 m while for inspection a bay width of up to 2.7 m is allowed.
Transom spacing is determined by the thickness of the boards supported, 38 mm boards require a transom spacing of no more than 1.2 m while a 50 mm board can stand a transom spacing of 2.6 m and 63 mm boards can have a maximum span of 3.25 m. The minimum overhang for all boards is 50 mm and the maximum overhang is no more than 4x the thickness of the board.