Merbau vs Jarrah vs Treated Pine: Best Decking Timber for Perth

Why Timber Choice Matters More in Perth Than Most of Australia

Perth's climate is genuinely tough on outdoor timber. Summers regularly exceed 40°C, UV intensity is extreme, and the combination of intense heat and occasional heavy rain creates significant expansion and contraction cycles in timber. Choose the wrong species or treatment level and you're looking at warping, cracking, and rapid degradation within a few years.

The three most common decking choices for Perth homes are Merbau, Jarrah, and treated pine. Each has distinct characteristics, price points, and ideal use cases.

Merbau

The most popular choice for good reason

Merbau is the dominant decking timber across Perth's northern suburbs, and for good reason. It's an imported hardwood (primarily from Papua New Guinea and Indonesia) with a Class 1 durability rating — meaning it's extremely resistant to decay and termite attack in above-ground applications.

•       Natural colour: Rich red-brown, deepens with age

•       Hardness: Very high — resists denting and surface damage

•       Durability rating: Class 1 above ground

•       Typical lifespan: 25+ years with proper maintenance

•       Price: Mid-to-high — typically $50-90 per lineal metre installed

•       Maintenance: Annual oiling recommended to retain colour and prevent surface checking

One thing to know about Merbau: it bleeds a red-brown tannin when first installed, especially when wet. This will stain pavers and concrete around your deck. Seal surrounding areas before installation and expect some initial bleed in the first year.

Jarrah

The West Australian classic

Jarrah is WA's iconic hardwood and has been used in Perth decks, homes, and public buildings for over a century. It's arguably the most beautiful of the three options — dense, rich, and deeply grained. It also has outstanding natural durability.

•       Natural colour: Deep red to red-brown

•       Hardness: Very high — one of Australia's hardest timbers

•       Durability rating: Class 1 in above and below ground applications

•       Typical lifespan: 30-50+ years with maintenance

•       Price: High — premium product, often $80-130+ per lineal metre installed

•       Maintenance: Annual to biennial oiling depending on exposure

Jarrah is increasingly expensive because supply is limited — old-growth Jarrah logging has been significantly curtailed in WA. Most Jarrah decking now comes from recycled sources, which actually makes for beautiful character timber but adds to the cost.

Treated Pine

The budget-friendly option

Treated pine (typically H3 or H4 treated radiata pine) is the most affordable decking option and is widely used across Perth. It's pressure-treated with preservatives that resist rot and termite attack, making it suitable for outdoor use.

•       Natural colour: Light yellow-green from treatment, fades to grey if left untreated

•       Hardness: Low to medium — dents and scratches more easily

•       Durability rating: H3 suitable for above ground, H4 for ground contact

•       Typical lifespan: 15-25 years with regular maintenance

•       Price: Low — typically $25-50 per lineal metre installed

•       Maintenance: Annual oiling or staining essential — bare pine greys and cracks quickly in Perth sun

Which Should You Choose?

For most Perth homes where budget allows, Merbau is the recommended choice — it balances cost, durability, and appearance well for WA's climate. If you want the best and are willing to pay for it, recycled Jarrah is unmatched. If budget is tight, H4 treated pine with a quality decking oil applied annually will serve you well.

Tip: Whatever timber you choose, the quality of the installation matters as much as the timber itself. Incorrect spacing, inadequate support bearers, and poor drainage design cause premature failure regardless of timber species.

Need help with your pool or home maintenance? Call Macca's on 0492 313 347 or visit maccaspoolandhousemaintenance.com.au for a free quote. Servicing Duncraig, Joondalup, Hillarys, Karrinyup, Sorrento, Scarborough and surrounding suburbs.