Quick Answer

A timber deck needs annual oiling or staining and a 6-monthly clean to stay protected against Melbourne’s wet winters and hot summers. Merbau and hardwood decks need penetrating oil every 12–18 months; treated pine every 12 months. DIY oiling costs $80–$200 in materials; professional re-oiling costs $400–$1,200 depending on deck size. Skip a season and you’re looking at costly sanding and restoration.

Annual Deck Maintenance Schedule

Task Frequency Time Required DIY Cost
Sweep and clear debris Monthly 15 minutes Free
Wash with deck cleaner Every 6 months 1–2 hours $25–$60
Inspect for rot, loose boards, popped screws Every 6 months 30 minutes Free
Sand back any rough or raised grain Annually 2–4 hours $30–$80 (hire sander)
Apply oil or stain Every 12–18 months 3–6 hours $80–$200
Tighten or replace fasteners As needed 1 hour $10–$40
Pro tip: The best time to oil a Melbourne deck is late autumn (April–May) or early spring (September–October) — when temperatures are mild and there’s no direct summer sun to dry the oil too quickly before it penetrates. Never oil in rain or if rain is forecast within 24 hours.

Deck Oiling vs Staining vs Decking Paint

Product Type Best For Lifespan Cost per 10m²
Penetrating oil (e.g. Feast Watson Decking Oil) Merbau, hardwood, treated pine 12–18 months $40–$80
Pigmented stain/tinted oil Greyed or weathered timber, restoring colour 18–24 months $50–$100
Film-forming decking paint Composite or damaged timber (not recommended for hardwood) 3–5 years (but peels if applied incorrectly) $60–$120
Water-based UV decking stain Treated pine, new timber 12–18 months $35–$70

Step-by-Step: How to Oil Your Deck

Step 1 — Clean the Deck Surface

Sweep off leaves and debris, then wash the deck with a dedicated deck cleaner (not household detergent, which leaves residue). Mix according to the label and scrub with a stiff deck brush. Rinse thoroughly with a garden hose or low-pressure washer (no more than 1,500 PSI on hardwood to avoid raising grain).

Step 2 — Allow Full Drying

Allow 24–48 hours of dry weather before oiling. In Melbourne’s autumn, this often means watching the Bureau of Meteorology forecast for a dry window. Oil applied to damp timber won’t penetrate and will sit on the surface, forming a sticky film that peels within weeks.

Step 3 — Sand if Needed

If boards have raised grain, splinters or grey surface oxidation that washing didn’t remove, sand lightly with 80-grit sandpaper along the grain. For whole-deck sanding, hire a belt sander or orbital floor sander from Kennards Hire or Kennards — expect $60–$100/day. Sweep and vacuum sanding dust thoroughly.

Step 4 — Apply the Oil

Work in small sections (2–3 boards at a time) using a wide paint brush, lambswool applicator or short-nap roller. Apply along the grain. Allow the first coat to soak in for 15–30 minutes, then wipe off any excess that hasn’t penetrated with a clean rag. Apply a second coat after 2–4 hours (check your product’s recoat time).

Step 5 — Inspect Boards, Fasteners and Frame

While the deck is clean and dry, inspect every board for: soft or spongy spots (early rot), large cracks running along the grain (check if structural), boards cupping or warping (may need replacement), and popped or rusted screws/nails. Tighten loose screws with a driver or replace with stainless 65mm deck screws from Total Tools or Bunnings ($15–$30 per box).

Dealing With Deck Rot

Soft or discoloured spots indicate fungal rot. Early-stage surface rot can be treated with a timber preservative (Timbaflex or similar, $30–$60) and the affected board stabilised. Deep rot that has penetrated more than 20% of a board’s thickness means replacement — a single merbau decking board (90mm x 19mm x 3.0m) costs $20–$35 at timber suppliers in SE Melbourne.

Safety warning: Deck rot in structural bearers, joists or posts is a serious safety risk — a person-sized load concentrated on a rotten joist can cause sudden collapse. If you suspect structural rot (soft, discoloured or sunken framing members visible underneath the deck), have the deck inspected by a licensed builder before use.

Top 10 Tips and Gotchas

  1. Never oil over old paint. If the previous owner painted the deck with film-forming paint, you must sand or strip it completely before oiling. Oil won’t penetrate paint.
  2. Merbau bleeds tannin. Merbau releases reddish-brown tannin when wet, which can stain concrete and pavers. Wash new merbau decks twice before first oiling to release surface tannin.
  3. Treated pine needs initial priming. New treated pine (H3 or H4 grade) should have an initial application of a decking primer or diluted first coat before the full oil application for better penetration.
  4. Oil rags are a fire risk. Linseed-oil-based products can self-ignite as rags dry. Spread used rags flat on concrete or immerse in water before disposal — never pile them in a bin.
  5. Check under your deck too. Poor air circulation under low-set decks causes moisture build-up and accelerates rot. Keep weeds and debris cleared from under the deck.
  6. Composite decks need different products. Composite/PVC decking doesn’t absorb oil — use a composite deck cleaner and UV-protective coating designed for the material.
  7. Use a test patch. Before oiling the whole deck, apply oil to a small hidden section and wait 24 hours to check the colour and absorption. Some aged timbers absorb unevenly.
  8. Don’t skip the in-between boards. Brush oil between boards and on the edges — these are the first surfaces to deteriorate as water sits between boards after rain.
  9. Stainless screws are worth the extra cost. Galvanised screws rust in outdoor conditions within 5–10 years, leaving rust stains on boards. Stainless steel 316 grade screws cost twice as much but never rust.
  10. Council approval for new decks. Replacing more than 25% of a deck’s structural framing may be considered a new structure requiring a building permit from your local council. Check with your Council’s building department.

Local Melbourne Resources

Frequently Asked Questions

How often should I oil my merbau deck in Melbourne?

Every 12–18 months for merbau, depending on sun exposure and foot traffic. Do the water bead test: splash water on the deck. If it soaks in immediately rather than beading, it’s time to oil. In exposed north-facing Melbourne decks, you may need to oil annually; shaded south-facing decks often last 18 months.

What’s the difference between deck oil and deck stain?

Deck oil is a clear or near-clear penetrating product that soaks into the timber, nourishing it and providing water repellency. Deck stain contains pigment (colour) in addition to the oil/resin base, which helps block UV damage and restores or changes the colour of greyed timber. Both penetrate rather than sit on the surface, unlike paint.

Can I oil my deck myself or should I hire a professional?

Oiling is a straightforward DIY job — cleaning, light sanding and applying oil are all within a handy homeowner’s ability and can save $300–$800 compared to a professional. Hire a professional for: whole-deck sanding back (requires heavy equipment), rot repair or board replacement, or if the deck is elevated and requires scaffolding or roof work access.

My deck is going grey and looks weathered — can it be restored?

Yes, in most cases. Surface greying (oxidation) on hardwood and merbau is purely cosmetic and can be removed with a deck cleaner containing oxalic acid (such as Cabots Deck Clean) or a light sand. Once clean and dry, apply a pigmented stain to restore colour. Deeply weathered or cracked timber may need a more thorough sand — hire a floor sander for $60–$100/day.