Plastic trestles and planks can be a practical, cost-effective option for many low-level DIY tasks around the home — but they are not a universal substitute for tube scaffolding. Whether they are appropriate depends on the working height, the load you need to carry, and the specific job at hand. Here's what every NZ homeowner should know before setting up a trestle platform.
What Are Plastic Trestles and Planks?
Plastic trestles (sometimes called sawhorse-style trestles) are lightweight, adjustable supports made from high-density polyethylene or similar materials. Paired with scaffold-grade planks (timber or LVL), they form a simple working platform. You'll find them at most NZ hardware stores including Bunnings and Mitre 10.
They are popular for tasks like:
- Interior painting and plastering at low heights
- Ceiling lining work in single-storey rooms
- Light maintenance jobs where a ladder is awkward
When Trestles and Planks Are Acceptable
For working heights up to 1.5 metres above the ground or floor level, a trestle-and-plank platform is generally considered acceptable for light-duty work. This is a common threshold referenced in NZ scaffolding guidance, though the specific requirements depend on the task and load involved.
Key conditions that must be met:
- The trestles must be rated for the intended load. Check the manufacturer's Safe Working Load (SWL) stamped on the trestle — never exceed it.
- Planks must be scaffold-grade and span no more than the trestle manufacturer recommends (typically no more than 1.2 m between supports for standard planks).
- The platform must be stable and level. Set up on firm, flat ground only.
- Only one person should be on a basic trestle platform at a time unless it is specifically rated for more.
- Trestles should be fully opened and locked before use — never use them partially folded.
When You Must Use Proper Scaffolding
Trestles and planks are not suitable in the following situations:
- Working height exceeds 1.5 m above the ground or floor (for most residential exterior work, this threshold is reached quickly on a single-storey home).
- Roof work or working near an open edge — edge protection and full scaffolding are required.
- Heavy loads such as stacked materials, masonry, or multiple workers.
- Exterior work on two-storey or higher buildings — tube-and-coupler or modular scaffolding with guardrails is required.
- Any situation where a fall could cause serious injury.
WorkSafe NZ sets out the requirements for working at height in New Zealand. Even for DIY homeowners, these guidelines represent best practice and should be followed to avoid serious injury.
NZ Height and Fall Protection Rules
Under NZ health and safety law, fall prevention measures are required whenever there is a risk of falling — regardless of height. For residential DIY, the practical guidance is:
- Under 1.5 m: Trestles and planks may be suitable with care.
- 1.5 m to 3 m: A more robust platform with guardrails, or proper scaffolding, is strongly recommended.
- Over 3 m: Full scaffolding with guardrails, toe boards, and a competent scaffolder is expected.
For context, the eave height of a typical NZ single-storey home is around 2.4–2.7 m, which already puts most exterior work above the safe trestle threshold.
Choosing the Right Planks
Not all planks are equal. For any working platform:
| Plank Type | Suitable? | Notes |
|---|---|---|
| Scaffold-grade timber (LVL or hardwood) | ✅ Yes | Must be inspected for splits or damage |
| Standard pine framing timber | ⚠️ Caution | Not recommended — can flex or split |
| Plastic scaffold boards | ✅ Yes | Check SWL and span rating |
| Chipboard or MDF | ❌ No | Not suitable for scaffolding use |
Always inspect planks before each use. Discard any that are cracked, warped, or show signs of rot.
Setting Up Safely — Practical Tips
- Place trestles on solid, level ground — never on loose soil, gravel, or uneven surfaces without packing.
- Ensure planks overlap the trestle support by at least 150 mm on each end.
- Keep the platform clear of clutter — trip hazards are a leading cause of falls.
- Never overreach from a trestle platform; move the platform instead.
- Have a second person present when working at any height, in case of an emergency.
- Wear appropriate footwear with good grip.
When to Call a Professional
If your job requires working above 1.5 m on the exterior of your home, near a roof edge, or on a two-storey or higher building, you should engage a licensed scaffolder. Professional scaffolding provides engineered guardrails, proper bracing, and load-rated platforms that trestles simply cannot match.
A qualified scaffolder will assess your specific site, select the right system, and ensure everything complies with NZ health and safety requirements. You can find experienced local scaffolders on tradedirectory.co.nz.
For any work that may also involve electrical lines near your home, contact your lines company before erecting any scaffolding — working near overhead lines carries serious electrocution risk. WorkSafe NZ has guidance on safe distances from power lines.
