Yes, it is often possible to add extra frames to a hired mobile scaffold tower — but only up to the maximum height specified by the manufacturer, and only if you follow the correct assembly sequence and safety requirements. Getting this wrong is genuinely dangerous, and in some situations the work must be carried out or supervised by a licensed scaffolder.
Understand the Manufacturer's Height Limits First
Every hired scaffold tower comes with a manufacturer's instruction manual, and that document sets the absolute maximum working platform height. Exceeding it is not just unsafe — it may also void any insurance you hold and put you in breach of your obligations under the Health and Safety at Work Act 2015.
As a general guide (not a guarantee for your specific tower), many aluminium mobile scaffold towers allow:
| Situation | Typical max platform height |
|---|---|
| Indoors on a firm, level floor | Up to around 8–12 m |
| Outdoors on firm, level ground | Often reduced — check manual |
| With outriggers/stabilisers fitted | Higher heights may be permitted |
| Without outriggers | Significantly lower limit |
Always confirm these figures with your hire company and the manual for your exact tower model.
The 3:1 Height-to-Base Ratio Rule
A key stability principle for mobile scaffold towers is the 3:1 ratio: the working platform height should not exceed three times the minimum base dimension. For example, if your tower base measures 1.5 m wide, the platform should be no higher than 4.5 m without outriggers or stabilisers fitted.
Once you add outriggers, the effective base width increases and you may be able to go higher — again, only to the manufacturer's stated limit. Never guess at this; check the manual or ring your hire company.
How to Safely Add Extra Frames
If you are within the permitted height and have the right components, follow these steps:
- Lock the castors before doing anything else. The tower must not move during assembly.
- Use only matching frames and components from the same system. Mixing brands or frame types is dangerous and not permitted.
- Add frames from the inside of the tower using the built-in climbing rungs — never lean a ladder against the outside of the tower to reach the top.
- Fit all horizontal braces and diagonal braces as specified in the manual at each new lift level. Do not skip bracing to save time.
- Refit the guardrails, mid-rails, and toe boards on the working platform every time you raise it.
- Check that the tower remains plumb and level after each addition.
- Keep the load on the platform within the rated capacity — confirm the rated capacity for your specific tower with the hire company and manufacturer's manual.
When a Building Consent or Licensed Scaffolder Is Required
Under the Health and Safety at Work (General Risk and Workplace Management) Regulations 2016, scaffolding over 5 metres in height is classified as restricted scaffolding work in New Zealand. This means it must be erected, altered, or dismantled by — or under the direct supervision of — a licensed scaffolder holding the appropriate certificate of competence.
If you are extending a hired tower so that the working platform will be 5 metres or more above the ground, you are legally required to have a licensed scaffolder involved. This is not optional.
For towers below 5 m, a competent person can assemble the tower, but WorkSafe NZ still expects you to follow the manufacturer's instructions exactly and manage the risks properly.
Separately, if your scaffolding is part of a larger construction project, check with your local council whether a building consent is required. Most short-term residential scaffold hire does not need a consent, but it pays to confirm — MBIE Building Performance has guidance on Schedule 1 exemptions.
Safety Checks Before Every Use
- Inspect all frames, pins, and braces for damage before assembly.
- Ensure the ground is firm, level, and capable of bearing the load.
- Never move a mobile tower with anyone or any tools on the platform.
- In windy conditions, do not use the tower — most manufacturers specify a maximum wind speed (often around 45 km/h).
- Keep bystanders clear of the base area.
Talk to Your Hire Company
Your scaffold hire company is your first point of contact. They can confirm the maximum height for your specific tower, supply the correct additional frames, and advise whether you need a licensed scaffolder for your job. If they are not able to answer these questions clearly, that is a warning sign.
When to Call a Professional
Call a licensed scaffolder if:
- The working platform will be 5 metres or higher above the ground.
- You are unsure about the stability, ground conditions, or correct assembly sequence.
- The tower needs to be erected on uneven ground, near an excavation, or in a confined space.
- The job involves public access areas or is adjacent to a road or footpath (additional requirements apply).
- You are not confident reading or following the manufacturer's manual.
A qualified local scaffolder can be found through tradedirectory.co.nz. Hiring a professional for a day or two is far cheaper than a serious injury or a WorkSafe investigation.
