3. Choosing the Right Kwila Board
6. How to Maintain Kwila Decking
7. Kwila Decking Troubleshooting
Kwila remains one of New Zealand's most popular hardwood decking timbers because it combines exceptional durability, stability, natural beauty and value for money. In this guide we'll explain everything you need to know before buying Kwila decking.
What is Kwila Timber?
Kwila is a premium, durable hardwood timber native to Southeast Asia and the Pacific, widely used in New Zealand for outdoor decking and landscape design.
Is Kwila Good for Decking?
Yes, Kwila is exceptionally good for decking. It is highly sought after due to its Class 1 durability rating, natural resistance to pests, and superior dimensional stability compared to other hardwoods.
How Long Does Kwila Decking Last?
Kwila is rated Class 1 for durability above ground - when properly installed and maintained, it can provide more than 40 years of reliable performance outdoors, with an average expected life expectancy of 25-40 years.
Why is Kwila Considered More Stable Than Other Decking Timbers?
Kwila has superior stability to other timber species, which means less movement (shrinkage) and lower rates of splitting, cupping, twisting, and warping.
Is Kwila Resistant to Pests?
Yes, Kwila is naturally resilient to problematic pests like termites, dry wood borers, and fungi.
Is SpecRite Kwila Sustainably Sourced?
Yes. All SpecRite Kwila is sustainably sourced from FSC®-certified forests, ensuring responsible forestry practices. Not all Kwila on the market is certified, so look for the FSC label before purchasing.
Learn more in our article: Why Choose FSC-Certified Timber?
Does Kwila Decking Look Good?
Yes, Kwila has a beautiful, rich colour, which varies from a light yellow-brown to a deep reddish brown and has an even, straight grain, with occasional golden flecks running through it.
It offers a premium, natural look that complements a wide variety of architectural and landscaping styles, from traditional homes through to modern outdoor entertaining spaces.
Research also shows that integrating natural materials (like timber) into our living spaces, has been shown to reduce stress and create more restorative environments, according to a recent study on biophilic design benefits.
What Else Can Kwila Be Used For?
Kwila can be used for decking, screening, fencing, pergolas, feature walls, seating and other outdoor structures.
Unlike composite alternatives, Kwila is available in a wide range of pre-sized profiles and lengths, meaning it can be used for a whole range of outdoor landscaping projects and features.
This flexibility opens up endless design possibilities and allows you to create a cohesive outdoor aesthetic. Explore your options by browsing the full SpecRite Kwila product range.
Kwila vs Composite Decking – Which Offers Better Value?
For most homeowners, Kwila offers better long-term value than composite decking, as well as outperforming treated pine decking and other hardwood alternatives.
Compared with plastic composite decking options, not only is Kwila nearly half the price, but for homeowners valuing natural beauty and durability, Kwila remains a superior choice when sourced responsibly and maintained properly.
If you're torn between natural timber and synthetic options, check out our head-to-head comparison: Kwila vs. Composite Decking.
Choosing the Right Kwila Board
Should I Choose Pre-oiled Kwila Decking?
Yes. Choosing pre-oiled Kwila decking is highly recommended because it provides immediate protection against moisture and UV damage during transit and installation. Pre-oiled SpecRite Kwila gives your deck an upfront layer of defence before you apply your final topcoat, as well as added protection to the underside of the decking boards.
Should I use Narrow or Wide Kwila Decking Boards?
The choice between narrow (90mm) and wide (140mm) boards depends on your deck's clearance height and design preferences:
- Choose 90mm boards for low-level decks, as the narrower profile offers superior structural stability and allows for more frequent ventilation gaps to prevent moisture buildup underneath.
- Choose 140mm boards if you are looking to achieve a modern, premium aesthetic on a standard, elevated deck.
- Choose a mix of both in a unique combination to elevate the look of your outdoor space.
Unsure which style fits your layout? Read our full guide: Wide vs Narrow Decking Boards: Which Is Best for Your Project?
What is the difference between solid random lengths and finger-jointed decking?
The main difference lies in how the boards are manufactured, which impacts their visual appearance, installation speed, and budget:
- Non-Oiled GripTread Random Lengths: A traditional grooved profile, supplied in a mix of varying board lengths from 1.8m to 5.7m, often installed with the groove face-up in a staggered butt-join deck layout.
- Pre-Oiled Solid Random Lengths: A mix of varying board lengths from 1.8m to 5.7m designed to create a modern-classic butt-join deck layout.
- Face Finger Jointed Set Lengths: Uniform 5.7m boards made by precision joining colour-matched shorter boards of timber. They feature a blended face join and come with a 25-year warranty (limited to joint failure).
Planning Your Kwila Deck
Are Decks Subject to Building or Planning Consents?
Decks in New Zealand may be subject to both building and planning requirements. Before you start planning your deck, it's worth checking whether your project needs a building consent, a resource consent, or both.
- Resource Consents: Whether you need a resource consent depends on your local council's District Plan. Factors such as your property's zoning, the deck's height and location, site coverage, heritage protections, natural hazard overlays, and proximity to boundaries can all affect the requirements, so it's best to check directly with your council.
- Building Consents: Building consents focus on ensuring the deck is structurally sound and complies with the New Zealand Building Code. Many low-level decks are exempt from needing a building consent, but this depends on specific height and design conditions set out in Schedule 1 of the Building Act 2004. However, even exempt decks must still meet the Building Code.
- Where to check: MBIE's Building Performance website and the "canibuildit" online tool are good starting points for understanding exemptions, and your local council can confirm what applies to your specific site and District Plan.
Because rules can be technical and vary by region, it's worth getting confirmation from your council, or a licensed building practitioner or surveyor, before purchasing materials or starting construction.
How Do I Know How Much Decking I Need?
For decking boards, the number of lineal metres you need can be found by dividing the area of the deck by the width of the decking boards. Don’t forget to incorporate ventilation gaps and add approximately 10% extra to your order for wastage and offcuts.
What Materials Should I Use for My Subframe?
The most common material for a decking subframe in New Zealand is treated radiata pine, although engineered timber, hardwood and galvanised steel framing systems are also used. Structural timber should be suitable for load-bearing applications and comply with the New Zealand Building Code and relevant New Zealand standards. Timber posts installed in the ground should generally be H5 treated, while above-ground structural framing such as bearers and joists is typically H3.2 treated - components close to ground level may require a higher treatment level. Components exposed to the weather should always have an appropriate treatment level for their intended use.
To determine the correct spacing for deck posts, bearer spans and joist spans, refer to NZS 3604:2011 – Timber-framed buildings, which provides span tables and construction requirements for light timber-framed buildings. The allowable spans depend on factors such as timber grade, member size, loading, and whether the deck is designed as a single-span or continuous-span structure. If your deck falls outside the scope of NZS 3604, specific engineering design may be required.
Should I Use Nails or Screws for Decking?
Stainless steel screws are highly recommended – 10g or 12g screws with a length of 50–65mm are suitable, depending on the thickness of the decking board.
Dome head nails that protrude from the timber can make the deck difficult to sand down and nailing should generally be avoided to minimise the risk of splitting the timber.
Kwila Decking Installation
While building a deck is a rewarding project, getting the installation details right will help ensure your deck looks great and lasts a lifetime.
Step 1 – Prepare the Frame
Fix your stumps, bearers, and joists.
Step 2 – Set Board Spacing
Accurate gapping is crucial to allow for natural timber expansion and ventilation. Aim for a minimum 5% gap between boards.
Step 3 – Fix the Boards
Pre-drill your holes using a countersink bit to avoid splitting the hardwood, then secure each board using two 50mm stainless steel screws per joist.
Step 4 – Finish and Protect the Deck
Apply a dedicated topcoat to seal the wood and lock in protection against heavy UV and moisture exposure.
For a comprehensive walkthrough of the entire building process, explore our step-by-step guide on How to Build a Deck and read our complete Kwila Decking Installation Guide.
How to Maintain Kwila Decking
Maintaining Kwila decking is simple. Clean it regularly and recoat it when the existing finish begins to wear and your Kwila deck will thrive.
We recommend applying a topcoat as soon as possible after installation to provide maximum protection to the timber. Our pre-oiled products can be top-coated with either an oil-based or water-based coating.
Depending on your local climate and your chosen topcoat, your deck could need refreshing every six months, or every few years. A high-end water-based finish will give you the longest lasting protection.
Follow our instructions on how to properly clean a timber deck, followed by how to topcoat your Kwila deck.
Kwila Decking Troubleshooting: Problems and Solutions
Why is My Deck Leaching Brown Liquid?
This is known as tannin bleed. Tannin is a natural substance in timber that leaches during its first few exposures to moisture, potentially staining nearby concrete or paving. You can naturally wash the tannins out with repeated hose-downs or apply a dedicated tannin remover upfront before final top-coating.
Why are My Decking Boards Moving?
It’s likely that the moisture below the deck is too high.
This can be caused by insufficient gapping, or limited airflow underneath the deck. Before building your deck, we recommend reading our Kwila Decking Installation Guide and factoring adequate ventilation, and additional drainage where needed.
Why is My Deck Turning Grey?
Because UV exposure gradually breaks down the colour at the timber surface if it isn't protected by a UV coating.
All outdoor timbers eventually grey off without maintenance. While some homeowners prefer the rustic, silvered off look, if you want to keep your deck’s rich colour it’s important to maintain a re-oiling schedule in line with your chosen top-coating product, and your local climate.
What are the Dark Patches on my Deck?
This is likely to be caused by iron stain, where trace metals – e.g. from muddy work boots, wire brushes, or cutting metal over your deck – react with the tannins in the timber, causing a chemical reaction. It can also be caused by poor quality fixings – stainless steel decking screws are recommended to avoid contamination from fixings.
Iron stain can occur in all timbers, and the best way to deal with it is to remove the source of the metal and clean the deck with an oxalic-based timber cleaner to remove the stains.
Ready to start your project? Browse our range of FSC® certified Kwila decking available at Bunnings.
The FSC® logo identifies products from forests that are certified against a set of strict environmental, social and economic standards in accordance with the rules of the Forest Stewardship Council®. You can check the current certification status of our SpecRite Kwila supplier at any time by visiting the FSC Search at search.fsc.org/en/ and entering Licence Code: FSC®-C128536.