140×19 Merbau Decking: What All Do You Need to Know

When designing a beautiful, long-lasting outdoor space, the choice of timber is paramount. Few materials blend tropical luxury with structural integrity as effectively as merbau decking. This imported hardwood has become a global favourite, renowned for its rich colour, exceptional durability, and high resistance to the elements. Whether you’re planning a sprawling entertainment area or a simple balcony, understanding the qualities of a merbau deck is key to a successful project.

This in-depth guide is designed to give you a complete understanding of the merbau decking 140 x 19 profile—why it’s a design favourite, its performance benefits, the critical installation steps required, and what you need to know about the merbau decking prices. Investing in this wider, more substantial board transforms an ordinary backyard into an elegant, expansive outdoor living space.

The Anatomy of Merbau: A Tropical Powerhouse

Merbau (Intsia bijuga) is a high-density, tropical hardwood sourced primarily from Southeast Asia. It is often referred to as “Kwila.” Its global popularity is rooted in a unique blend of natural beauty and structural integrity, making it perfectly suited for challenging outdoor environments.

Distinguished Aesthetics

• Rich, Deep Colour: Merbau is famous for its vibrant colour palette, ranging from golden-brown to a deep reddish-brown when new. When oiled, the colour intensifies into a rich, warm mahogany that creates an immediate sense of luxury and warmth on your merbau deck.
• Unique Grain: It features a moderately coarse texture and often an interlocked grain pattern, contributing to its stability. A signature feature is the presence of small, yellow mineral deposits within the wood, which shimmer as tiny gold flecks, adding to its exotic appeal.

Durability Class 1 Performance

Merbau is classified as a Durability Class 1 timber for use above ground. This is the highest durability rating achievable, confirming its exceptional resilience:

• Longevity: Merbau boasts an expected service life of 40 years or more, making it a true long-term investment.
• Pest and Rot Resistance: The timber’s natural density and high oil content make it highly resistant to fungal decay, rot, and common wood-boring insects, including termites.

Why Choose the 140×19 Merbau Decking Profile?

While merbau timber decking is available in standard widths (like $90 \text{mm}$), the 140 x 19 merbau decking board offers significant advantages that appeal directly to modern design trends and practical installation needs.

1. The Expansive Design Effect

The difference between $90 \text{mm}$ and $140 \text{mm}$ is not just $50 \text{mm}$; it’s a complete shift in visual scale.

• Fewer Lines, Greater Flow:The wide $140 \text{mm}$ boards dramatically reduce the number of visible joins and gaps on the deck surface. This creates a cleaner, more continuous aesthetic, which is the hallmark of high-end, contemporary design.
• Apparent Size Increase: By reducing the visual clutter of multiple lines, the deck appears significantly larger and more expansive, a key trick for maximising the perceived space in any outdoor area.
• Showcasing the Timber: The 140 x 19 merbau decking board acts as a wider canvas, allowing the rich colour, deep tones, and unique grain patterns of the Merbau to be better appreciated.

2. Enhanced Structural Feel

The $140 \text{mm}$ width adds a visual weight and solidity to the entire structure. The $19 \text{mm}$ thickness provides a sturdy walking surface that feels substantial and premium underfoot.

3. Installation Efficiency

From a labour perspective, using 140 x 19 merbau decking is highly efficient. Fewer boards are needed to cover the same area, which translates directly to:

• Reduced Fastener Count: Less drilling, less screwing, and fewer overall fixings are required.
• Faster Laying Time: The installation process is often faster, potentially leading to reduced labour costs.

Installation Essentials: The Merbau Tannin Factor

The most crucial step specific to merbau decking is managing its natural tannins (oils) before or during installation.

The Risk of “Bleeding”

Merbau’s durability comes from its high oil content. When the wood is exposed to moisture (rain, dew, or washing), these dark reddish-brown tannins leach out, or “bleed.” If this runoff comes into contact with surrounding surfaces, such as concrete, paving, or pool coping, it will cause severe and permanent reddish-brown staining.

Mandatory De-Tanning (Pre-Washing)

To prevent staining, the boards must be thoroughly de-tannined before installation or immediately after, but before any oil is applied.

• Preparation: Lay the merbau decking boards on a disposable surface away from sensitive areas.
• Application: Apply a dedicated de-tannin or decking cleaning solution (typically oxalic acid-based).
• Washing: Scrub the boards with a stiff-bristle brush and rinse thoroughly with clean water.
• Repeat: Repeat the process two to three times until the water running off the boards appears clear or very light in colour.
• Drying: Allow the timber to dry completely before fastening or oiling.

Fastening and Substructure for 140mm Boards

The wider 140mm merbau decking profile requires careful attention during fastening to ensure long-term stability and to prevent potential cupping (where the edges of the board lift).

1. Essential Fastening Strategy

• Pre-Drilling is Non-Negotiable: Merbau’s high density requires a pilot hole to be pre-drilled for every screw. Failing to pre-drill will cause the timber to split and can break the fasteners.
• Double Fastening: Due to the width, it is highly recommended to use two screws at every joist, spaced approximately $20 \text{mm}$ in from the edges, to anchor the board securely and minimise the risk of cupping.
• Stainless Steel: Always use high-quality stainless steel screws (Grade 304 minimum, 316 near saltwater) to prevent rust and black staining.

2. Hidden Fixings

For the cleanest, most luxurious look that emphasises the wide merbau decking boards, consider a hidden fastening system. These systems secure the boards from the side or underneath, leaving the surface smooth and completely screw-free.

3. Ventilation is Key

A crucial part of any merbau timber decking project is a well-ventilated substructure. Ensure a minimum ground clearance and ample cross-flow ventilation beneath the deck. This allows the wide boards to dry evenly, preventing moisture build-up that leads to cupping and decay.

Budgeting for Your Merbau Deck

When calculating the total cost of merbau decking, you need to consider more than just the price of the merbau decking boards.

• Merbau Decking Price Per M2 (Materials): The price is typically quoted per lineal meter or per square meter. 140 x 19 merbau decking will have a higher lineal meter cost than $90 \text{mm}$ boards, but the merbau decking price per m2 will be more competitive as fewer lineal meters are needed to cover the area. Expect the merbau decking prices to be in the mid-to-high range for hardwoods.
• Accessories: Factor in the cost of high-quality stainless steel fasteners, oil, de-tanning cleaner, and the cost of the substructure materials.
• Labour: Installation of $140 \text{mm}$ boards is marginally easier due to fewer fixings, but the mandatory pre-drilling and de-tanning processes add to the labour time. Always get detailed quotes for installation.

Conclusion

The 140×19 merbau decking profile offers the ultimate blend of tropical luxury, Class 1 durability, and modern sophistication. By committing to the critical de-tanning process and ensuring proper fastening for the wider boards, your merbau deck will deliver a stunning, low-maintenance outdoor space that will stand the test of time, significantly enhancing the value and beauty of your home. Choosing Merbau decking 140 x 19 is a decision that invests in enduring elegance.
Ready to transform your space with quality that lasts? Explore the range at Melbourne Timber Supplies—your go-to source for Hardwood Decking in Australia.

Frequently Asked Questions (FAQ)

1. Q. Why is pre-drilling mandatory for 140×19 merbau decking?
   Merbau is an extremely dense hardwood. Due to this hardness, attempting to drive screws without a pilot hole will almost certainly cause the timber to split and may also cause the fasteners to snap. Pre-drilling is essential for a professional finish and long-term board integrity


2. Q. How much does 140×19 merbau decking cost compared to a standard size?
   While the lineal meter price of 140 x 19 merbau decking is higher than $90 \text{mm}$ boards, the merbau decking price per m2 is often competitive because fewer wide boards are needed to cover the same area. Always request a quote based on the square meterage for an accurate comparison of the overall material cost.


3. Q. What is the best way to maintain the rich colour of the 140×19 merbau decking?
   To maintain the deep reddish-brown colour, you must apply a high-quality, UV-protectant decking oil with a Merbau or “redwood” tint. This should be done annually or every 18 months, depending on sun exposure, after thoroughly cleaning the deck.


4. Q. Can I use the 140×19 merbau decking around a swimming pool?
    Can I use the 140×19 merbau decking around a swimming pool? Yes. Merbau’s Durability Class 1 rating and natural resistance to moisture and decay make it highly suitable for pool surrounds. However, due to the staining risk, it is absolutely vital to complete the de-tanning process to protect the pool coping and surrounding paving from tannin runoff.


5. Q. Does the 140mm width increase the risk of the boards warping or cupping?
   Does the 140mm width increase the risk of the boards warping or cupping?