Building a simple timber step or small landing outside is a satisfying DIY project that many NZ homeowners can tackle themselves — but getting the basics right matters for safety, durability, and compliance with the NZ Building Code. Here's what you need to know before you pick up a hammer.
Do You Need a Building Consent?
This is the first question to answer. Under Schedule 1 of the Building Act 2004, some small outdoor steps and landings are exempt from building consent — but the rules depend on the size, height, and whether the structure is attached to your home.
As a general guide:
- A single step or a landing no more than 1.5 m² in area and no more than 200 mm above ground is often exempt.
- Anything higher, larger, or attached to the house in a structural way may require consent.
- Decks and landings more than 1 m above ground almost always need consent.
Always confirm with your local council before starting. Exemptions can vary, and getting it wrong can cause problems when you sell your home. You can also check guidance from MBIE Building Performance for general information on consent requirements.
Choosing the Right Timber
Outdoor timber must be treated to resist rot, moisture, and insects. In New Zealand, look for timber with the appropriate Hazard Class (H) rating:
| Location | Recommended Hazard Class |
|---|---|
| Above ground, sheltered | H3.1 or H3.2 |
| Ground contact (posts, bearers) | H4 |
| In-ground (footings) | H5 |
For treads and framing above ground, H3.2 treated pine is a common and cost-effective choice. For any timber going into or near the ground, use H4 treated as a minimum. Hardwoods like kwila or spotted gum are also popular for treads due to their durability and appearance, but check they are responsibly sourced.
You'll find treated timber at Bunnings, Mitre 10, and PlaceMakers.
Planning Your Step or Landing
Before cutting anything, sketch out your design and take measurements. Key things to plan:
- Rise and going: The NZ Building Code (Clause F4) sets requirements for stair geometry. For external steps, a rise of 150–190 mm and a going (tread depth) of at least 250 mm is a good target for comfort and safety.
- Width: A minimum of 900 mm clear width is recommended for a single-person step or landing.
- Drainage: Slope the landing surface slightly (around 1–2°) away from the house so water doesn't pool.
- Handrails: If your step or landing is more than 1 m above the ground, a handrail or balustrade is required under the Building Code. Even for lower structures, a handrail adds safety.
What You'll Need
Materials:
- H3.2 treated timber for framing and treads (e.g., 140×45 mm or 190×45 mm)
- H4 treated posts or bearers if going near ground level
- Galvanised or stainless steel fixings (joist hangers, post brackets, screws, bolts) — never use bare steel outdoors as it will rust
- Concrete or post footings if required
- Decking oil or exterior timber stain for finishing
Tools:
- Tape measure, square, spirit level
- Circular saw or drop saw
- Drill/driver
- Post hole digger or spade (if setting posts)
Step-by-Step Construction
1. Prepare the Ground
Clear the area of vegetation and ensure the ground is firm and level. If you're setting posts into the ground, dig holes at least 450 mm deep (deeper in soft or clay soils) and use concrete to secure them.
2. Set Your Bearers and Frame
Install your bearers (the horizontal supports) level and at the correct height. Use galvanised post brackets where possible to keep timber off the ground and improve airflow. Check everything is square with a builder's square.
3. Fix the Joists
Attach joists across the bearers at no more than 450 mm centres for standard decking boards, or as required for your tread thickness. Use galvanised joist hangers for a strong, tidy connection.
4. Lay the Treads or Decking
Fix your treads with two galvanised or stainless screws per joist. Leave a 3–5 mm gap between boards for drainage and timber movement. Pre-drill near board ends to prevent splitting.
5. Finish and Protect
Once built, apply a quality exterior timber oil or decking stain to protect the wood from NZ's UV and moisture. Products from Resene or Dulux include good exterior timber ranges — follow the manufacturer's instructions for preparation and application.
Safety Tips
- Always wear appropriate PPE: safety glasses, hearing protection when cutting, and gloves.
- Check for underground services before digging — call Before U Dig (0800 248 344).
- Ensure the structure is stable and secure before use.
- Refer to WorkSafe NZ for general safe working guidelines.
When to Call a Professional
While a simple ground-level step is well within reach of a capable DIYer, consider hiring a qualified carpenter if:
- Your project requires a building consent
- The landing is elevated (more than 600 mm off the ground)
- You're unsure about structural connections or footing design
- The work involves attaching to the house structure (which may also trigger consent)
A Licensed Building Practitioner (LBP) is required to carry out or supervise certain restricted building work. Check LBP for more information. You can find experienced local carpenters on tradedirectory.co.nz.