Scaffolding Couplers

Scaffolding Couplers are the fittings which hold the tubes together. There are three basic types: scaffolding right-angle couplers, scaffolding putlog couplers and scaffolding swivel couplers. To join tubes end-to-end scaffolding joint pins (also called spigots) or sleeve couplers are used, or both together. Only right angle couplers and swivel couplers can be used to fix tube in a ‘load bearing connection’. Single couplers are not load bearing couplers and have no design capacity.

Other common materials include base plates, ladders, ropes, anchor ties, reveal ties, gin wheels, sheeting, etc.

 Despite the metric measurements given many scaffolders measure tubes and boards in imperial units. With tubes from 21 feet down and boards from 13 ft down.

A working platform requires certain other elements to be safe. They must be close-boarded, have double guard rails and toe and stop boards. Safe and secure access must also be provided.

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.

Scaffolding Tubes

Scaffolding Tubes are made of either aluminum or steel. Generally if they are steel they are painted either ‘black’ or they are galvanised. The scaffold tubes come in a variety of lengths and a standard diameter of 48.3 mm. (1.5 NPS pipe). Scaffolding tubes are generally bought in 6.3 m lengths and can then be cut down to certain typical sizes.

The main difference between the two types of scaffolding tubes is the lower weight of aluminum scaffolding tubes (1.7 kg/m as opposed to 4.4 kg/m) and also a greater flexibility. Which means the advantage of steel over aluminum is its greater resistance to force.