Key takeaways
- Merbau decking $320-$520/m2 fitted in Adelaide (2026) - the mid-priced hardwood option
- Merbau leaches red-brown tannin for 6-12 months; sealing board ends before fixing prevents staining of paving below
- Kiln-dried or properly seasoned merbau is essential - green merbau cups and splits within 2 summers
- We connect you with 3 independent builders so you compare itemised quotes on identical scope
Jump to: indicative costs, common questions, or the full cost guide.
Why merbau is the Adelaide default
Merbau (also sold as kwila) is a dense Southeast Asian hardwood. It is the most common decking timber in Adelaide for good reasons: it is hard-wearing, naturally resistant to rot and termites, takes oil beautifully, and the deep red-brown colour suits both heritage and modern homes. It costs less than spotted gum or blackbutt and more than treated pine, so it sits in the value sweet spot.
It is stable once seasoned, which matters in Adelaide's swing between bone-dry summers and wet winters. The key word is seasoned. Green, unseasoned merbau still holds construction moisture and will cup, twist and develop wide gaps within 2 summers. A builder who specifies kiln-dried or air-dried merbau is protecting your deck; one who quotes cheap, fast-delivered stock often is not.
Tannin bleed - the merbau detail that catches people out
Merbau contains a large amount of tannin. For the first 6 to 12 months a new merbau deck leaches a red-brown liquid every time it rains or is hosed. Left unmanaged, that tannin stains pale paving, render and light pool surrounds below and around the deck.
This is normal and it is manageable. A builder who knows merbau seals the cut ends and sometimes the full board before fixing, advises you to hose the deck a few times before sealing it, and warns you to protect adjacent paving early. It is the difference between an experienced merbau installer and a builder treating it like any other board.
Decking Adelaide passes your job to 3 builders who quote merbau as an itemised scope: frame, boards, stainless fixings, sealing and oil. Any deck over $20,000 inc GST must be built by a BWC-licensed contractor under a written contract with building indemnity insurance.
Merbau Decking costs in Adelaide
Indicative 2026 ranges. No SERP competitor publishes structured pricing - we do, so you can sanity-check any quote.
| Deck type | Indicative range |
|---|---|
| Merbau decking, fitted | $320-$520 / m2 |
| Merbau decking, supply only | ~$70-$120 / m2 |
| Small merbau deck (15-25 m2, ground level) | $8,000-$13,000 |
| Medium merbau deck (25-50 m2, one stair set) | $13,000-$28,000 |
Indicative metro Adelaide ranges for 2026. Board grade, height, footings and balustrading move the price. Your 3 quotes will be itemised.
BWC licence verified
Every builder we connect you with holds a current SA Building Work Contractor's licence, checked on the CBS register.
Itemised quotes
Frame, boards, fixings, oil and balustrades as separate line items - so you compare like for like.
Independent builders
Real, licensed Adelaide deck builders - never a cash-only operator working without insurance.
Merbau Decking - frequently asked questions
Merbau leaches tannin for its first 6 to 12 months. Hose the new deck several times to flush the surface tannin, protect adjacent pale paving and render during that period, and have the builder seal the board ends before fixing. After the bleed settles, an oil coat locks the colour. An experienced merbau installer manages all of this as standard.
Fitted, merbau runs $320 to $520 per square metre in metro Adelaide for 2026. A small ground-level deck of 15 to 25 square metres is roughly $8,000 to $13,000; a medium 25 to 50 square metre deck with one stair set is $13,000 to $28,000. Comparing 3 itemised quotes on the same scope is the only reliable way to price it.
They suit different priorities. Merbau is cheaper upfront, runs cooler underfoot in summer and has genuine timber warmth, but it needs oiling every 1 to 2 years. Composite costs more and can get hot, but never needs oiling. Our merbau vs composite guide weighs them up with real Adelaide pricing.
Every 12 to 24 months in Adelaide, depending on sun exposure and foot traffic. A fully exposed, north-facing merbau deck fades faster and needs annual oiling; a shaded deck can stretch to 2 years. Letting merbau go grey is a choice, not a fault - but oil protects the surface as well as the colour.
Avoid the cash-only cowboy
The biggest decking risk in South Australia is an unlicensed, cash-only builder. With no BWC licence there is no building indemnity insurance, no recourse through CBS or SACAT if the work fails, and your house insurance can decline rot or structural claims tied to unlicensed work. Here is how to tell the two apart.
Walk away if
- Cash only, no written contract, no GST invoice
- Cannot give a BWC licence number to check
- Wants a deposit well above the 5% legal cap
- Quotes a single lump sum with no itemised breakdown
A real builder has
- Current BWC licence, verifiable on the CBS register
- Written contract and building indemnity insurance over $20,000
- Deposit at or under the 5% legal cap
- Itemised quote - frame, boards, fixings, finish, balustrades
Every builder we connect you with is BWC-verified. Read our full guide to BWC licensing in South Australia.
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