The Complete Scaffold Parts & Fittings Guide

Every scaffold, whatever its size or purpose, is built from the same basic building blocks. Tubes, couplers, transoms, base plates and boards, combined in the right configuration, are what turn a pile of steel into a safe working platform. Get the wrong component, or fit it incorrectly, and the consequences on site can be serious.

This guide covers what you need to know about scaffold components and fittings, what they are, why they matter, the main types used on UK sites, and how to choose and source the right ones for your project.

Scaffold components are the physical parts that make up a scaffold structure. Standards are the vertical tubes that carry the load down to the ground. Ledgers run horizontally along the length of a scaffold, and transoms run across it, supporting the boards that form the working platform. Base plates spread the load of each standard onto the ground.

Scaffold fittings are the connectors that hold these components together. Couplers join tubes at right angles or at any angle, base plates take the tube into the ground, and clamps secure boards and toe boards in place. On a traditional tube and fitting scaffold, every one of these connections is made individually on site using loose fittings rather than pre engineered node points.

Scaffold tube itself has an industry standard outer diameter of 48.3mm, whatever the material or wall thickness. Altrad Generation supplies steel tube in both 4.0mm wall (conforming to EN39:2001 Grade S235GT) and 3.2mm wall (conforming to BS EN10219-1 Grade S355JOH), plus a lightweight aluminium option (EN755-2 Grade 6082 T6). This shared diameter is what allows any standard coupler to fit any standard tube, regardless of manufacturer.

The components and fittings you specify directly affect whether a scaffold stands up safely under load, and whether it can be erected, altered, and dismantled without unnecessary risk.

Load bearing depends on the fitting, not just the tube. A tube is only as strong as the connection holding it in place. A drop forged double coupler carries a minimum slip load of 9.1kN under BS EN 74-1:2005. A putlog coupler is rated to a lower safe working load of 0.63kN under BS 1139 2.2:2009, because it is designed for a different job. Using the wrong fitting for the load it needs to carry is one of the most common causes of scaffold failure.

Compliance is not optional. Scaffolding in the UK falls under the Work at Height Regulations 2005, and structures are typically designed and erected in line with the NASC TG20 guidance. Components and fittings that carry the relevant British and European standard marks give a scaffolder and a principal contractor confidence that the structure has been designed and tested to a known, verifiable benchmark.

The right component saves time. Choosing purpose built transoms, correctly rated couplers, and the right tube grade for the job reduces the number of decisions made on the fly during erection, and cuts the risk of using an unsuitable fitting because it was the one to hand.

Scaffold Tube

Scaffold tube is the core building block of any traditional scaffold. Altrad Generation supplies three grades. Hot dipped galvanised tube (4.0mm wall, EN39:2001 Grade S235GT) is the strongest option, suited to tall structures and heavy loads. High yield galvanised tube (3.2mm wall, BS EN10219-1 Grade S355JOH) is around 20% lighter than standard 4.0mm tube while offering higher yield strength, reducing handler fatigue across a large build. Aluminium scaffold tube (EN755-2 Grade 6082 T6) is lighter again, and suited to applications where ease of handling matters more than maximum load capacity. All three are available in stock lengths from 5ft (1.5m) up to 21ft (6.4m) for steel, or 20ft (6.09m) for aluminium.

Couplers

Couplers are the fittings that join tubes together. A double coupler joins two tubes at a fixed right angle and is rated to a minimum slip load of 9.1kN under BS EN 74-1:2005. A swivel coupler joins two tubes at any angle, rated to 6.1kN under the same standard. Both are available in drop forged steel, for the highest strength applications, or pressed steel, a lighter and more economical option for standard work. Other fittings in the range include sleeve couplers for joining tubes end to end, joint pins, girder couplers for fixing to structural steelwork, and base plates for transferring standard loads to the ground.

Transoms

A transom is the horizontal tube that runs across a scaffold, supporting the boards that form the working platform. Traditional transoms are cut lengths of scaffold tube fixed with putlog or right angle couplers. Altrad Generation also supplies pre engineered options such as the Readylok Transom, a pre coupled unit with preset couplers built in, designed to reduce loose fittings and speed up erection while maintaining TG20 compliance.

Match the fitting to the load. Check the slip load or safe working load rating of any coupler against the load it will actually carry, and confirm it carries the relevant standard mark, BS EN 74-1:2005 for double and swivel couplers, or BS 1139 2.2:2009 for putlog couplers.

Check for testing and certification. Every coupler and fitting used on a UK scaffold should be manufactured and tested to a recognised British or European standard. A fitting without a visible standard mark, or one that has been repeatedly repaired or reshaped, should not be trusted to carry load.

Choose the tube grade for the job. Heavier 4.0mm steel tube suits tall or heavily loaded structures. Lighter 3.2mm high yield tube reduces weight and handler fatigue across a large build. Aluminium tube suits applications where portability outweighs maximum load capacity.

Consider the scaffold type. A putlog scaffold, tied into the building itself, needs putlog couplers and putlog heads rather than the double and swivel couplers used on an independent scaffold. Decide the structure type before ordering components.

Decide between hire and purchase. For a single project or short term requirement, hiring components and fittings is usually the most practical option. For scaffolders running a continuous programme of work, purchasing stock can work out more cost effective over time.

Altrad Generation supplies the full range of scaffold components and fittings for hire and sale across the UK, including:

• Hot Dipped Galvanised Tube: 4.0mm wall, EN39:2001 Grade S235GT.

• High Yield Galvanised Tube: 3.2mm wall, BS EN10219-1 Grade S355JOH.

• Aluminium Scaffold Tube: EN755-2 Grade 6082 T6, lightweight alternative to steel.

• Scaffold Fittings: the full coupler, clamp, and base plate range in drop forged and pressed steel.

• Drop Forged Double Coupler: right angle connection, 9.1kN minimum slip load, BS EN 74-1:2005.

• Drop Forged Swivel Coupler: any angle connection, 6.1kN slip load, BS EN 74-1:2005.

• Drop Forged Putlog Coupler: attaches putlogs and transoms to ledgers, BS 1139 2.2:2009.

• Putlog Head: flattened blade fitting for putlog scaffolds.

• British Standard Base Plate: distributes standard loads to the ground.

• Readylok Transom: pre coupled transom units for faster, TG20 compliant erection.

Contact Altrad Generation to discuss your project requirements and get a quote.

Scaffold components and fittings might be the smallest items on a site delivery note, but they carry the largest consequences if the wrong one is used. Matching the right tube grade, coupler, and transom to the job, and confirming every fitting carries the standard mark it should, is the foundation of a safe and compliant scaffold. Altrad Generation supplies the full range of scaffold components and fittings for hire and sale across the UK. Contact your local branch to discuss your requirements.

Q. What is the difference between a transom and a putlog?
A. Both are horizontal tubes that support the boards on a scaffold, but they connect differently. A transom sits between two rows of standards on an independent scaffold, fixed at each end with a right angle coupler. A putlog is used on a putlog scaffold, where one end rests on the ledger and the other end, fitted with a flattened putlog head, is built directly into the brickwork of the structure under construction.

Q. What size is a standard scaffold tube?
A. Standard scaffold tube in the UK has an outer diameter of 48.3mm, whatever the material or wall thickness. Steel tube is available with a 4.0mm wall (EN39:2001 Grade S235GT) or a lighter 3.2mm wall (BS EN10219-1 Grade S355JOH), and aluminium tube is available with a 4.0mm wall (EN755-2 Grade 6082 T6). Stock lengths run from 5ft (1.5m) up to 21ft (6.4m) for steel, or 20ft (6.09m) for aluminium.

Q. How are scaffold fittings tested and certified?
A. Scaffold couplers and fittings are tested against defined standards before they carry a compliance mark. Double and swivel couplers are tested to BS EN 74-1:2005, which sets a minimum slip load each fitting must achieve before it can be certified. Putlog couplers are tested to BS 1139 2.2:2009. When ordering fittings, check that the standard mark is present and that the fitting has not been damaged, repaired, or reshaped in a way that could affect its tested performance.