Merbau vs Composite Decking: Which Is Right for Adelaide?

Upfront cost: merbau wins clearly

There is no contest on the upfront number. Merbau decking is $320 to $520 per square metre fitted in Adelaide. Composite is $480 to $920. For a medium 40 square metre deck that gap is roughly $6,000 to $16,000 - real money.

Merbau costs less because the board itself is cheaper to produce. Composite carries the cost of manufacturing a wood-plastic board and capping it with a protective polymer shell. If the upfront budget is the binding constraint, merbau is the answer.

Maintenance: composite wins clearly

This is where composite earns its premium. A merbau deck needs oiling every 1 to 2 years in Adelaide to hold colour and protect the board - a fully sun-exposed deck closer to annually. Each recoat of a 30 square metre deck is $600 to $1,400 paid, or a couple of weekends done yourself. Over 15 to 20 years that is a significant recurring cost.

A composite deck never needs oiling, staining or sanding. It needs an occasional wash to clear pollen and dust, and that is the entire maintenance burden. Capped composite holds its colour with no intervention.

Add the lifetime maintenance to the upfront cost and the gap between the two narrows considerably - which is the whole financial argument for composite.

The Adelaide heat factor

This factor is specific to a climate like Adelaide's and most brochures skip it. Dark composite boards in direct summer sun reach 60 to 70 degrees - too hot to stand on barefoot in January. Timber, including merbau, stays noticeably cooler because it does not hold heat the same way.

It does not rule composite out. The fix is to choose a lighter board colour for any barefoot area - around a pool, off a bedroom - and to factor in afternoon shade. But if a barefoot deck in full sun is the brief, merbau has a genuine comfort advantage.

Look, feel and the honest verdict

Merbau is real timber: warm, with grain and character, and it ages. Composite is consistent and low-fuss but, even at the premium end, reads as a manufactured board to some eyes. Some homeowners love the no-fuss uniformity of composite; others find it lacks the warmth of timber. That one is personal.

The honest verdict: if you are keeping the home 15-plus years and value never oiling a deck again, composite's maintenance saving builds a real case despite the upfront premium. If you might move within 5 years, want timber warmth, or have a tight upfront budget, merbau is the better call. Either way, get 3 itemised quotes on the same scope - that is how you compare like for like.