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Yellow Balau (Bangkirai) Decking Smooth 21 x 145mm

Price From: (exc VAT) £14.23 (inc VAT) £17.08
(exc VAT) (inc VAT)
Price per linear metre £5.83 £7.00
Price per square metre £38.87 £46.64

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Price From: (exc VAT) £14.23 (inc VAT) £17.08


Yellow Balau - Bangkirai - is a very durable hardwood, well suited to deck construction. It is one of the most popular species in the UK for hardwood decking. With a mixture of warm colours of golden browns, light browns and pale reddish-browns, Yellow Balau offers a unique colour range which will sit beautifully within a natural environment.

At a glance

  • Interlocking grain and fine even texture
  • Hard, heavy and strong suited for deck construction
  • Smooth face with beveled edges
  • Colours vary from yellow-brown to pale red-brown
  • Silva Recommended Finish - Sansin Dec
    Yellow Balau looks best in one of these colour tones...
    Harvest Gold (Natural) | Autumn Gold | Espresso

Hardwood Decking with interlocking grain and fine even texture

Yellow Balau decking boards are supplied with a smooth face and beveled edges.

Yellow Balau (pronounced Bal-Ow) - Bangkirai - is a very durable hardwood. It is a hard, heavy and strong timber that is well suited to deck construction.

Yellow Balau decking has an interlocking grain and a fine and even texture. Its colour varies between yellowish-brown, brown and pale reddish-brown. Occasional pinhole and hit and miss is acceptable within the grading rules of Yellow Balau decking.

Storage and Handling 

For best results store your Yellow Balau decking out of direct sunlight and do not expose it to weather before installation.  Keep the boards off the ground by stacking them flat on timbers placed on the ground; this allows air to circulate around the stack.  Cover your deck boards with a waterproof breathable sheet to protect them from sun and rain until you are ready to install them.

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Coverage - 1m2 = 6.69 metres of board
Grade - Standard and Better
Hardness - 1560lbf
Botanical name - Shorea spp
Origin - Southeast Asia
Wood Type - Hardwood

Recommended fasteners: 5.0 x 60mm Countersunk Stainless Steel Screws

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Case Study

Yellow Balau hardwood decking delivers contemporary look and natural feel

Finishing & Protection

Even though Yellow Balau is highly durable in its natural state we recommend that Yellow Balau decking be finished on all four sides prior to installation to help prevent surface checking, discolouration and cupping.

Why Pre-finish?

  • Enhances the natural beauty of wood
  • Ensures a consistent finish
  • Applied in factory conditions
  • Long lasting protection against weathering
  • Simple maintenance routine
  • Reduces onsite labour costs

The importance of sanding

As Yellow Balau is an incredibly dense species it is essential to sand the deck boards prior to applying the finish. Sanding opens up the cells on the surface to allow the stain to properly penetrate. This facilitates deeper penetration of the stain for a consistent appearance and longer service life.

What is weathering?

There is a risk involved when leaving wood exposed to the elements. During the weathering process wood can appear unsightly as the material can blacken due to moisture getting into the fibres and pulling out tannins and extractives. Finish protects the wood from moisture absorption and UV degradation.

Installation & Advice

Deck Board Spans

21 x 145mm Yellow Balau decking should be installed with joists spaced at 400mm centres.  When installing the boards diagonally the joists should be spaced at 300mm centres.

Deck Board Spacing

21 x 145mm Yellow Balau decking should be installed with a 5mm gap between the boards.  The space between the boards allows for air circulation and slight expansion with changes to the humidity level.


It is important to allow adequate air circulation underneath the deck to prevent cupping and warping of the boards.  It is recommended that a vapour barrier is used on the ground to prevent moisture from absorbing into the underside of the deck boards.


There are a number of different options available for fastening deck boards to the joists.  We recommend screwing through the face of every board using 5.0 x 60mm Countersunk Stainless Steel Screws. Fix two screws into every joist at quarter points on the deck board (36mm from each edge).  We recommend that pilot holes are drilled prior to inserting the screws.  This is particularly important at the ends of the boards to prevent splitting. 5.0 x 60mm Countersunk Stainless Steel Screws will flex slightly as the wood expands and contracts as the level of humidity changes with the changing of the seasons.

For a cleaner finish we suggest recessing the screws and using plugs to hide the screw heads.  Plugs can be cut from off-cuts of decking using a relatively inexpensive drill attachment called a plug cutter. 

Hardwood wrench

The longer the deck board the greater the tendency for it to be slightly bowed. To overcome this, most professional deck installers will carry a tool called a Hardwood Wrench, or Bow wrench, which enables the user to easily straighten a bowed board single handed as it is installed.  The Bow wrench is relatively inexpensive and can save a lot of time, so it’s worth buying even if you only use it for one project.  It can also he hired from some tool hire stores.

End Sealer

Yellow Balau decking from Silva Timber is end-sealed during the manufacturing process to help prevent splitting and checking on the ends of boards.  We recommend that if the boards are cut during installation then the exposed end grain should be sealed as soon as possible.   A clear, water-resistant wax such as Osmo Wax End Sealer should be used.

Cleaning and Maintenance 

Your Yellow Balau deck will benefit from regular cleaning.  Brush the deck with a stiff broom to remove dirt and dead leaves, and ensure that the gaps between the boards are clear of organic debris.  Clean the deck periodically with Multi Wash by Sansin® to remove grime and mildew.  Yellow Balau decking can be pressure washed, but it is important to select a low setting to prevent the wood fibres on the surface from being damaged.

If your Yellow Balau deck is weathered it is possible to restore the natural colour with Wood Cleaner by Sansin®.  This product will remove weathering, mould, algae, mildew and iron stains and prepares the surface for recoating. 

If an existing finish or stain has broken down it can be removed using Paint and Stain Remover by Sansin®.  This product will remove most failed oil-based or latex finishes, extreme weathering, water stains, mould and mildew and restore wood to its natural colour.


Yellow Balau decking can be crosscut with good quality chop saw using a tungsten carbide tipped blade.  Ripping can be done on a standard table saw, using a good quality, well-aligned fence and a tungsten carbide tipped blade.  When drilling, always use the highest quality drill bits available. If screwing through the face, use a countersink bit with a positive stop to ensure that all the screw heads end up at a consistent depth.  Screws can be lubricated to make installation easier.

Routing or planing can be done with either high speed tungsten carbide cutters. The feed speed should be fairly slow. 


A dust mask and eye protection should always be worn when working with any wood.  Avoid the inhalation of wood dust.  We recommend a dust mask with an activated carbon filter. Some people may have an allergic reaction to hardwood dust.  Remove wood splinters immediately to prevent infection.


To ensure its quality, Yellow Balau decking from Silva is carefully manufactured, graded and inspected at source.  It is inspected again during the order picking process prior to despatch.  However, Yellow Balau decking is a natural wood product and is subject to variations in weight, density, colour, grain and performance. Yellow Balau decking is subject to dimensional changes as the moisture content in the wood fluctuates with humidity in the air. Swelling, shrinkage, checking, and other movement of individual pieces are normal occurrences in wood decking.


Grade - Standard and Better

Timber is a beautiful, natural and versatile material that cannot be replicated by any man made product. It is the only building material that is naturally renewable and truly sustainable.

Timber is manufactured from trees which have developed naturally and responsively to their environment. Being a 100% natural product it varies from one piece to another, each having variations in grain patterns and colour.

We understand that for the uninitiated buying timber can be a daunting process, so this section of the website has been written with the novice in mind. We’ve attempted to explain how and why timber is graded and what to expect when you receive a delivery of timber from us. We’ve also included relevant sections from the grading rules, and to help you understand these rules we’ve included definitions of natural characteristics and manufacturing irregularities.  By the time you have read and digested all this, you will probably know more about the subject than most of the staff at your local timber merchant!

Whilst there is no doubting the importance of grading rules, it should be stated that the same grade can differ from one supplier to the next, just as the quality of apples will differ from one greengrocer to the next. Here at Silva we’ve gone to great lengths to source the very best products available.  Rather than buying on an ‘ad-hoc’ basis from a series of different suppliers we prefer to form long term relationships with reliable mills that focus on quality and consistency. 

We are confident in the quality of our products and we want you to be confident with your purchase, which is why we invite you to visit our premises in Widnes to see our products first hand before placing an order. We even encourage you to visit our competitors first so that you can compare our quality to theirs.

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