Scaffold couplers must be tightened to the correct torque to keep a scaffold structure safe and stable — under-tightened couplers can slip under load, while over-tightening can crack the coupler body or damage the tube. In New Zealand, the accepted standard torque for most right-angle and swivel scaffold couplers is 50 Newton-metres (Nm), as referenced in general scaffolding best practice and applicable standards — confirm the specific standard with your supplier or a certified scaffolder. Checking and achieving this torque requires the right tool and a clear process.
Why Coupler Torque Matters
Scaffolding is a safety-critical structure. A coupler that isn't tightened properly can rotate or slide along the tube, causing ledgers, transoms, or standards to shift — potentially leading to a partial or full collapse. WorkSafe NZ treats scaffolding failures seriously, and both the person erecting the scaffold and the person in control of the worksite can be held liable if a structure is unsafe.
In New Zealand, scaffolding over 5 metres in height must be erected, altered, or dismantled by — or under the direct supervision of — a Certified Scaffolder (or higher). Even for lower scaffolds, the work must be done competently and safely.
The Correct Torque Specification
For standard tube-and-coupler scaffolding, the widely accepted torque for forged steel couplers (right-angle, swivel, and putlog types) is:
| Coupler Type | Recommended Torque |
|---|---|
| Right-angle (double) coupler | 50 Nm |
| Swivel coupler | 50 Nm |
| Putlog / single coupler | 50 Nm |
| Sleeve / joint pin coupler | Per manufacturer spec |
Always check the manufacturer's specification for the specific couplers you are using, as some pressed-steel or proprietary couplers may have different requirements. If you don't have the data sheet, contact your supplier.
Tools You Need
To check and set coupler torque correctly, you need a scaffold torque wrench — a standard shifting spanner or podger will not give you a reliable torque reading. Scaffold torque wrenches are specifically calibrated and typically have a 19 mm or 7/16" square drive fitting to suit scaffold coupler nuts.
- Torque wrench rated to at least 60 Nm (with a clear scale)
- 19 mm socket or scaffold spanner head to suit the coupler nut
- Ensure the wrench is calibrated and in good condition — a worn or damaged torque wrench gives unreliable readings
Torque wrenches can be hired from most tool hire companies if you don't own one.
How to Check Coupler Torque Step by Step
1. Inspect the coupler first
Before checking torque, visually inspect each coupler for cracks, deformation, or corrosion. A damaged coupler should be removed and replaced — do not attempt to torque a faulty fitting.
2. Set your torque wrench
Set the torque wrench to 50 Nm (or the manufacturer's specified value). Make sure the wrench clicks or signals at the correct setting — read the instructions for your specific wrench model.
3. Apply the wrench to the coupler nut
Fit the socket squarely onto the coupler nut. Apply steady, smooth pressure in the tightening direction. If the wrench clicks (or signals) before you apply significant force, the coupler is already at or above the target torque — do not over-tighten.
4. If the nut turns before the click
If the nut rotates before the wrench signals, the coupler was under-tightened. Continue tightening until the wrench signals at 50 Nm, then stop.
5. Work systematically
Check every coupler in sequence — don't skip any. Mark checked couplers with a chalk mark or tape if it helps you keep track on a large scaffold.
6. Re-check after initial loading
Couplers can settle slightly once the scaffold is loaded (planks, workers, materials). It is good practice to re-check torque after the first use of a newly erected scaffold.
Common Mistakes to Avoid
- Using a standard spanner by feel — this is not reliable and is not an acceptable substitute for a torque wrench
- Over-tightening — this can crack cast or pressed couplers and strip threads
- Ignoring damaged couplers — a cracked coupler body will not hold torque safely regardless of how tight you make it
- Not checking after bad weather — heavy wind or rain events can warrant a re-inspection of the whole scaffold
Legal Requirements and Licensing in NZ
Under the Health and Safety at Work Act 2015 and associated regulations, scaffolding is classified as Prescribed Suspended Work when above certain heights. WorkSafe NZ requires that scaffolds over 5 metres be erected by a Certified Scaffolder holding a relevant certificate of competence. For scaffolds between 5 and 10 metres, a Restricted Scaffolder certificate may apply depending on the configuration.
For scaffolding at or below 5 metres, a competent person may erect it, but they must still understand and apply safe practices — including correct coupler torque. Always check with your local council and refer to MBIE Building Performance if you are unsure whether your project requires a building consent or a licensed professional.
When to Call a Professional
You should engage a licensed, certified scaffolder if:
- The scaffold is over 5 metres in height
- The scaffold is on a sloped, uneven, or unstable surface
- You are working near power lines or other hazards
- You are unsure about any aspect of the structure's integrity
- The scaffold will be used by multiple workers or members of the public
A qualified scaffolder will have calibrated torque wrenches, the right training, and the experience to spot problems you might miss. You can find licensed scaffolders in your area on tradedirectory.co.nz.
