Timber choice changes how a deck looks on day one and how it behaves in year five. These are the boards we use most in coastal NSW and what to expect from each.
Merbau
The default hardwood for good reason: stable, durable, widely available in 90mm and 140mm, and it takes oil beautifully. Fresh Merbau bleeds tannin, so it needs to be laid and coated with that in mind, especially over light-coloured paving or render.
Tallowood
An Australian hardwood with excellent durability and a warmer, more golden tone than Merbau. Very hard-wearing underfoot and a standout in 140mm widths. It's our pick when a client wants a local hardwood rather than an import.
Spotted Gum
Beautiful variation and colour movement across the boards, and extremely durable. The variation is the point — if you want a uniform floor, it is not the right board.
Treated pine
The budget option for surfaces, and the standard choice for subframes as H3 or H4 treated timber. As a decking surface it dents easily and needs regular coating, but as a subframe under hardwood or composite it does its job well.
Board width and fixing
- 140mm boards give a broader, more architectural look with fewer gaps to clean, and suit larger decks.
- 90mm boards move less and suit smaller or highly exposed areas.
- Consistent, correctly spaced fixings matter more than the timber species for how flat the deck stays.
- Joist spacing must match the board — over-spanned joists cause the bounce and cupping people blame on the timber.
Common questions
Which decking timber lasts longest near the coast?
- Durability class 1 hardwoods like Tallowood and Spotted Gum, kept coated, will outlast Merbau and treated pine in salt air — but the subframe and fixings decide the real lifespan of the deck.
Is Merbau still worth using?
- Yes. It is stable, cost-effective and looks excellent oiled. Just plan for tannin bleed in the first rain events after installation.
What is the hardest decking timber?
- Among common options, Spotted Gum and Tallowood are the hardest wearing, which is why they hold up so well in high-traffic entertaining areas.