Merbau Timber Decking Melbourne

Greenhill Timbers stocks Merbau at our yard at 170 Settlement Road, Thomastown, with pickup or delivery across Melbourne and regional Victoria. Merbau has been our specialty since we started out importing timber. This page lists every Merbau line we carry: decking boards in 90, 140 and 190 mm, dressed Merbau from 42 × 19 to 290 × 42 mm, and solid-face Merbau posts, each with its lengths and price.

Merbau decking boards: sizes, lengths and prices

All our Merbau decking is 19 mm thick, kiln-dried and Standard and Better grade, with a smooth face and a reeded reverse. Prices are as at 3 October 2026 and include GST; each product page shows the current price.

Board Lengths Price
90 × 19 mm set lengths 1.8 to 5.7 m in 300 mm steps, plus 1.0 m 1.8 m $9.54 · 3.0 m $19.44 · 5.7 m $49.02
90 × 19 mm random lengths Mixed lengths from 1.8 to 5.7 m $6.00 per lineal metre
140 × 19 mm set lengths 1.8 to 5.7 m in 300 mm steps, plus 1.0 m 1.8 m $17.55 · 3.0 m $34.20 · 5.7 m $76.38
140 × 19 mm random lengths Mixed lengths from 1.8 to 5.7 m $10.45 per lineal metre
140 × 19 mm long length random Long lengths only, 4.2 to 5.7 m $12.50 per lineal metre
190 × 19 mm set lengths 1.8, 2.1 and 2.4 m 1.8 m $49.50 · 2.1 m $57.75 · 2.4 m $66.00

Set lengths, random lengths or long lengths?

Set lengths let you order the exact lengths on your deck plan, so joins land on joists where you want them and little is wasted. Random lengths are a mix between 1.8 and 5.7 m at a lower price per metre; you plan the joins around the lengths you receive. Long length random is 4.2 to 5.7 m only, for wide decks, boardwalks and long runs with far fewer end joins.

How much Merbau decking do I need?

With a 4 mm gap, 90 mm boards take about 10.6 lineal metres per square metre. With a 5 mm gap, 140 mm boards take about 6.9. Add 5 to 10% for cutting.

Worked example, a 20 m² deck in random lengths: in 90 × 19 mm you need about 213 m, so order 230 m, which is about $1,380 of boards. In 140 × 19 mm you need about 138 m, so order 150 m, which is about $1,570. The narrow board costs less in timber but takes about half as many boards again to lay and screw down.

Dressed Merbau for screens, handrails and pergolas

Dressed all round, kiln-dried, Select grade, sold per length. The price shown is for the shortest length. See the dressed Merbau category for working notes.

Size Used for Lengths Price
42 × 19 mm Slatted screens, fence infill 1.8 to 4.2 m from $4.61
70 × 19 mm Screens, gates, hardwood pickets 1.8 and 2.1 m from $8.91
38 × 38 mm Battens and light framing 1.0 to 4.2 m from $7.35
42 × 42 mm Batten screens and balusters 1.8 to 3.6 m from $13.25
90 × 42 mm Handrails and rails 1.8 to 5.7 m from $32.95
140 × 42 mm Beams, fascias and stair stringers 1.8 to 5.7 m from $56.70
190 × 42 mm Pergola beams and rafters 1.8 to 5.7 m from $80.53
240 × 42 mm Pergola beams 1.8 to 5.7 m from $111.32
290 × 42 mm Large beams and feature fascias 1.8 to 5.7 m from $125.82
140 × 42 mm laminated, finger-jointed Long straight beams 4.2 and 5.4 m from $153.88

Merbau posts

Laminated Merbau posts with a solid face on all four sides, for pergolas, verandahs and outdoor rooms where the post is on show.

Post Lengths Price
90 mm post 2.4 to 6.0 m from $108.00
115 mm post 2.4 to 6.0 m from $187.18
140 mm post 2.4 to 6.0 m from $302.28

Merbau Decking Installation Tips

Getting the installation right is just as important as choosing quality timber. At Greenhill Timbers, these are a few recommendations we give customers to help maximise the life of their Merbau deck.

1. Oil All Sides of the Boards

Before installation, we recommend applying a quality decking oil such as Cutek to all sides of each Merbau board, including the underside and cut ends. This helps reduce uneven moisture absorption, improves stability and provides added protection against the weather.

2. Protect Your Joists with Joist Protection Tape

Install joist protection tape on the top of every timber joist before fixing the decking boards. The tape creates a waterproof barrier that helps prevent moisture from becoming trapped around screw penetrations, reducing the risk of joist rot and significantly extending the life of the subframe.

3. Allow for Proper Board Spacing

Always leave the recommended gap between decking boards to allow for natural expansion, contraction and drainage. Correct spacing also improves airflow beneath the deck and helps prevent moisture build-up.

4. Seal All Fresh Cuts

Whenever a board is cut to length, apply decking oil or an appropriate end-grain sealer to the freshly cut end. This helps protect the exposed timber from moisture ingress and weathering.

5. Use Quality Stainless Steel Fixings

For the best long-term performance, use high-quality 316 stainless steel screws or concealed fixing systems, particularly in coastal or high-moisture environments. This helps prevent corrosion and staining over time.

6. Ensure Good Ventilation

A well-ventilated subframe allows air to circulate beneath the deck, reducing trapped moisture and helping the timber remain stable throughout the seasons.

7. Wash Before Final Oiling

Merbau naturally contains tannins that can bleed when exposed to moisture. We recommend washing the deck after installation and allowing it to dry thoroughly before applying the final coat of decking oil.

Greenhill Timbers Tip: Taking a little extra time during installation—such as oiling the underside of the boards and protecting your joists with tape—can significantly extend the life of your deck and reduce future maintenance.

Merbau timber facts

Merbau (Intsia bijuga and Intsia palembanica) is a hardwood from Southeast Asia and the Pacific. It is orange-brown when freshly cut and darkens to a deep red-brown with age.

  • Density and hardness: about 830 to 860 kg/m³, Janka hardness 8.5 kN.
  • Durability: Class 1 above ground, the highest rating, with termite-resistant heartwood.
  • Bushfire: on the AS 3959 list of bushfire-resisting timbers, accepted for decks up to BAL-29.
  • Stability: kiln-dried, so boards move less after they are laid.
  • Tannin: Merbau bleeds a brown tannin when it first gets wet. Hose the boards down or let them weather for a few weeks before oiling, and keep run-off away from pale paving and render.

Questions we get asked about Merbau decking

90 mm or 140 mm boards?
90 × 19 mm is the classic look and each board moves less across its width. 140 × 19 mm gives a wider, more contemporary deck with fewer boards, joins and screws.

Is set length or random length cheaper?
Random lengths cost less per metre. Set lengths cost a little more but waste less on a small deck, because you buy only the lengths on your plan.

What joist spacing does Merbau decking need?
450 mm centres for 19 mm boards laid square to the joists, or 350 mm when the boards run at 45 degrees.

How often does Merbau need oiling?
Clean it regularly and re-oil every 12 to 24 months, depending on how much sun and rain the deck gets. Ask us about pre-oiled boards.

Can Merbau be used in a bushfire area?
Yes, up to BAL-29. Tell us the rating on your bushfire report and we will confirm the boards and fixings to suit.

Do I need a permit for a deck?
Most decks in Victoria do, especially if attached to the house or more than 800 mm off the ground. Our deck permit guide explains the rules.

Everything else for the deck

Screws, joist hangers, stirrups and joist tape are in decking accessories. CUTEK, Intergrain and Sceney’s oils are in decking oil and paint. For the frame, see H3 treated pine, or the ClickDeck aluminium subframe. Comparing timbers? Read Merbau vs Spotted Gum, or see all hardwood decking.

Bring your deck size in, or call (03) 9465 9875, and we will work out boards, lengths, screws and oil. If another timber suits your project better, we will tell you.

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