A single-step deck landing is one of the more achievable weekend DIY projects for a NZ homeowner — but it still needs to be built correctly to be safe, durable, and compliant with the NZ Building Code. Get the foundations, framing, and fixings right from the start and you'll have a landing that lasts for decades.
Does Your Landing Need a Building Consent?
Many small deck landings fall under Schedule 1 exemptions of the Building Act 2004, meaning they don't require a building consent. As a general guide, a single-level deck that is no more than 1.5 m above the ground and meets certain size limits may be exempt — but check with your local council for the specific conditions that apply. However, the rules can vary depending on your specific site, council, and proximity to boundaries or other structures.
Always check with your local council before you start. You can also find guidance on exemptions at MBIE Building Performance. Getting this wrong can cause problems when you sell your home.
Planning Your Landing
Before you pick up a hammer, think through these key points:
- Size and purpose: A typical single-step landing at a door threshold is around 900 mm × 900 mm minimum, though 1200 mm × 1200 mm gives more comfortable space.
- Step height (riser): The NZ Building Code (Clause D1) requires risers to be between 115 mm and 225 mm. Aim for a consistent, comfortable height — around 150–175 mm is common.
- Step depth (going): The going (horizontal depth of the step) should be at least 240 mm for comfort and safety.
- Drainage: The deck surface should slope slightly away from the house — around 1:100 — so water doesn't pool against the cladding.
Choosing the Right Timber
Using the correct treated timber is non-negotiable in NZ's variable climate. Untreated or under-treated timber will rot quickly, especially in contact with or near the ground.
- H3.2 treated timber is the minimum for decking boards and framing above ground.
- H4 treated timber is required for any framing in contact with or close to the ground (within 150 mm).
- H5 treated timber is needed for posts or bearers in direct ground contact.
Check the BRANZ guidelines or your timber supplier for confirmation. Suppliers like Mitre 10, Bunnings, and PlaceMakers stock a range of treated structural timber.
For decking boards, hardwoods like kwila or treated pine are popular NZ choices. Composite decking is also an option if you prefer low maintenance.
Footings and Bearers
A solid landing starts below ground:
- Mark out your landing area with string lines and pegs, checking for square using the 3-4-5 triangle method.
- Dig footing holes to a depth recommended by your council or engineer — typically 400–600 mm for a small landing, below the frost line in colder regions.
- Pour concrete footings and set post anchors or stirrups while the concrete is wet. Allow at least 24–48 hours to cure before loading.
- Set your posts or bearers on the anchors. For a low single-step landing, you may use short H5 posts or concrete pads with H4 bearers sitting on top.
Framing the Landing
With footings in place, frame up the landing deck:
- Use 90 × 45 mm H3.2 treated framing (joists) at no more than 450 mm centres for standard 90 mm decking boards, or 600 mm centres for thicker boards — check your timber supplier's span tables.
- Fix joists to bearers using joist hangers and hot-dipped galvanised (HDG) or stainless steel fixings — never use plain steel, which will corrode.
- If the landing butts up against the house, fix a ledger board to the wall framing using appropriate structural fixings. Ensure the ledger is below the interior floor level and that flashing is installed to prevent moisture ingress behind the cladding.
Laying the Decking Boards
- Leave a 3–5 mm gap between boards for drainage and expansion.
- Fix boards with HDG or stainless steel screws — two per board per joist. Pre-drill near board ends to prevent splitting.
- Ensure the finished deck surface sits at least 150 mm below the door threshold to keep moisture away from the interior.
- Trim boards flush with a circular saw once all are fixed.
Building the Step
For a single step down from the landing:
- Cut stringers (the angled side supports) from H3.2 or H4 treated timber, depending on ground proximity.
- Fix a riser board (if using a closed riser design) or leave open for drainage.
- The tread should overhang the riser by 15–25 mm (the nosing) and be at least 240 mm deep.
- Ensure the step is firmly fixed and cannot rock or shift.
Finishing and Safety Checks
| Check | Requirement |
|---|---|
| Riser height | 115–225 mm (consistent) |
| Step going (depth) | Minimum 240 mm |
| Deck slope | ~1:100 away from house |
| Fixings | HDG or stainless steel |
| Timber treatment | H3.2 minimum above ground |
| Surface grip | Non-slip boards or strips |
Add non-slip strips or choose a decking profile with a ribbed surface, especially in shaded or damp areas. This is particularly important for older household members.
When to Call a Professional
While a small landing can be a DIY job, consider hiring a qualified deck builder or Licensed Building Practitioner (LBP) if:
- Your site has unusual ground conditions, slopes, or drainage issues.
- The landing connects to restricted building work (e.g., structural wall connections).
- You're unsure about consent requirements.
- The landing is part of a larger deck project.
You can find experienced local deck builders on tradedirectory.co.nz. For LBP verification, visit Licensed Building Practitioners.
Safety note: Always wear appropriate PPE when cutting treated timber — a dust mask rated for treated timber dust, safety glasses, and gloves. Treated timber offcuts must be disposed of correctly and never burned.
Licensed Building Practitioner (LBP)
