"Low maintenance" gets thrown around a lot in decking marketing, and it's fair for Merbau — but fair doesn't mean zero. Knowing exactly what to do and when, rather than a vague "oil it sometimes," is what actually keeps a Merbau deck looking good for its full 30-40 year lifespan. Here's the real year-by-year schedule.
Year One: What to Expect (Tannin Phase, First Oiling)
Every Merbau deck construction project starts its maintenance story the same way: with tannin bleed in the first few weeks and months, which is normal and not something to treat. Alongside that, we recommend the first oil coat within the first month of installation. It's earlier than most people expect, but oiling early enhances the timber's colour and adds protection while the boards are still settling in, rather than waiting and letting the surface weather unprotected in the meantime.
Ongoing Oiling Frequency for Coastal Homes
After that first year, Merbau settles into a routine: an oil treatment roughly every 12-18 months keeps the colour rich and adds ongoing protection. Where your deck sits changes the exact timing — a full-sun deck, or one close enough to the water to catch regular salt spray, is better oiled closer to the 12-month mark. A sheltered, shaded deck away from direct salt exposure can often stretch to 18 months or slightly beyond before it needs another coat.
Cleaning Between Oil Treatments
Cleaning is the maintenance that happens far more often than oiling, and it matters just as much. A regular sweep to clear leaves and debris from between boards, and an occasional wash with a soft broom and mild detergent, keeps grime and organic matter from building up. On coastal properties, hosing off salt residue periodically helps too. This is also the point where it's worth checking gaps between boards stay clear — trapped debris holding moisture against the timber is a bigger long-term risk than a slightly overdue oil coat.
Products We Recommend (Cutek, Intergrain)
We typically recommend penetrating hardwood oils like Cutek or Intergrain, which are designed for dense timbers like Merbau and suit Central Coast conditions well. These soak into the timber rather than sitting on the surface, so they don't peel. Film-forming coatings — varnishes, polyurethanes, anything that forms a surface layer rather than penetrating — are worth avoiding on Merbau specifically, since they tend to peel and look poor on a dense hardwood that naturally moves with moisture and temperature.
What Happens If You Skip Maintenance
Skip the oiling and the main consequence is cosmetic: the timber silvers to a grey patina instead of holding its reddish-brown colour, on a similar timeline to leaving it untreated from day one. That's a legitimate look plenty of owners choose deliberately, not a failure. The real risk isn't skipped oil — it's skipped cleaning. Leaves, dirt and moss left to build up in board gaps and shaded corners trap moisture against the timber, and that's what eventually leads to the kind of localised rot or damage that needs professional attention. If your deck's been neglected for a while and you're not sure whether it's just weathered or genuinely due for work, our deck repair and restoration team can assess it.
Low-Maintenance Alternative: Letting It Silver Naturally
If regular oiling isn't something you want to commit to, you genuinely can do nothing. Left unoiled, Merbau — like most hardwood decking — weathers to a silvered grey over its first year or two and then holds that look, still performing structurally for decades. It's a legitimate low-maintenance path, not a compromise; plenty of our clients choose it deliberately for the aged, weathered aesthetic and simply skip the oiling routine entirely. If you'd rather avoid timber maintenance altogether, including the option to weather naturally, composite decking is the alternative that needs neither oiling nor a silvering trade-off.
Whichever path you choose — a regular oiling routine or letting it silver naturally — a Merbau deck rewards a little planning with decades of use. If you want a maintenance schedule tailored to your deck's aspect and exposure, get in touch.