Planking a scaffold bay correctly is one of the most critical steps in setting up a safe working platform. Done right, it gives you a stable, secure surface to work from; done wrong, it can cause a serious fall or collapse. Here's what you need to know before you start, including NZ-specific requirements and when the job must be left to a licensed professional.
Understanding NZ Scaffold Regulations First
Before touching a single board, it's important to understand the legal framework. In New Zealand, scaffolding is governed by WorkSafe NZ under the Health and Safety at Work Act 2015 and associated regulations. For scaffolding over 5 metres in height, the work must be designed, erected, altered, and dismantled by a licensed scaffolder — this is restricted work under the Health and Safety at Work (Scaffolding) Regulations.
For lower-level domestic scaffolding (typically under 5 metres), a competent homeowner may be able to erect a basic platform, but you must still meet the minimum safety standards. If you're in any doubt, check with WorkSafe NZ or engage a qualified scaffolder found on tradedirectory.co.nz.
What Are Standard Scaffold Timber Boards?
Scaffold boards (also called scaffold planks) used in NZ must meet specific requirements to be safe. Key specifications include:
- Dimensions: Typically 225 mm wide × 38 mm thick (nominal), though actual dressed sizes may vary slightly
- Length: Common lengths are 1.8 m, 2.4 m, 3.0 m, and 3.6 m
- Timber grade: Must be structural-grade timber, free from large knots, splits, shakes, or decay — do not use general framing timber or pallet timber as a substitute
- Condition: Boards must be inspected before use; discard any that are cracked, warped, or show signs of rot
Always source boards from a reputable supplier such as PlaceMakers, Mitre 10, or Bunnings, and confirm they are rated for scaffold use.
Preparing to Plank the Bay
Before laying boards, make sure the scaffold frame itself is correctly erected, plumb, and stable. Check that:
- All ledgers and transoms (horizontal members) are properly secured
- The scaffold is tied to the structure where required
- The ground is level and base plates or sole boards are in place
- You have a safe means of access (ladder or stair unit) before you start working at height
How to Lay Scaffold Boards Safely
1. Calculate the Number of Boards Needed
A standard scaffold bay is typically 1.2 m to 1.8 m wide. You'll need enough boards to cover the full width of the working platform without gaps wider than 25 mm between boards. Gaps larger than this create a trip hazard and risk of tools or debris falling through.
2. Check Board Overhang (Cantilever)
This is one of the most important rules:
| Overhang Rule | Minimum | Maximum |
|---|---|---|
| Board overhang past transom | 150 mm | 4 × board thickness (approx. 150 mm for 38 mm board) |
In practice, aim for an overhang of 150 mm past the support transom past the support transom. Too little and the board can tip; too much and it becomes a lever that can flip under load. The general rule of thumb is: overhang must not exceed four times the board thickness.
3. Prevent Board Movement
Boards must not be able to slide, tip, or lift during use. Secure them by:
- Using board clips or cleats nailed or screwed to the underside at each end to hook over the transom
- Alternatively, use proprietary scaffold board retaining clips designed for the frame system you're using
- On windy sites, additional securing may be needed to prevent boards lifting
4. Lapping Boards End-to-End
If boards need to be joined along their length, they must lap over a transom — never join boards mid-span. The lap should be sufficient to provide a secure bearing over the transom — check the applicable WorkSafe guidance or your scaffold system's specifications for the minimum required lap and the joint must sit directly over a support.
5. Check the Platform Width
For a working platform (where people work and materials are placed), the minimum width under NZ guidelines is generally 450 mm for light work, but 600 mm or more is strongly recommended for comfort and safety. Always check the specific requirements for your task.
Edge Protection and Guardrails
Once the platform is planked, edge protection is mandatory on any platform where a person could fall more than 1 metre. This means:
- A top rail at 900 mm–1100 mm above the platform
- A mid rail at approximately 450 mm–500 mm
- A toe board (kick board) at least 150 mm high to prevent tools rolling off
Do not skip this step — it is a legal requirement under WorkSafe regulations.
Inspecting the Platform Before Use
Before anyone steps onto the completed platform:
- Walk the boards and check for any movement, bounce, or instability
- Confirm all boards are fully supported at both ends
- Check that no boards are cracked or have shifted during installation
- Ensure guardrails and toe boards are in place
Platforms should be re-inspected after any event that could affect stability — such as high winds, heavy rain, or impact.
When to Call a Professional
You must engage a licensed scaffolder if:
- The scaffold platform is 5 metres or more above the ground
- The scaffold is complex (e.g., cantilevered, suspended, or on an uneven or sloped site)
- The work involves restricted scaffold work as defined by WorkSafe NZ
- You are unsure about any aspect of the design, load capacity, or tie requirements
A licensed scaffolder will ensure the platform meets all legal requirements and can provide a handover certificate confirming the scaffold is safe to use. Find a qualified local scaffolder on tradedirectory.co.nz.
