Quick Answer
A DIY timber deck restoration (clean, sand, restain) costs $150–$400 in materials for a standard 20m² deck and takes a weekend. Replacing a few rotted boards adds $50–$200 per board in timber costs. Autumn is the ideal time for Melbourne homeowners — the surface is dry, temperatures are mild, and you’re sealing the timber before winter rain arrives.
Melbourne’s weather is hard on timber decks — UV in summer bleaches the surface grey, rain and moisture cause mould, and temperature swings loosen screws and split boards. If your deck is looking tired but structurally sound, autumn is the perfect time to restore it. This step-by-step guide covers everything from replacing damaged boards through to the final stain coat.
What You’ll Need
| Item | Cost | Where to Buy |
|---|---|---|
| Timber deck cleaner (e.g. Cabots, Feast Watson, Intergrain) | $20–$45 per 4L | Bunnings, Mitre 10, hardware stores |
| Random orbital sander (hire) or pole sander | $60–$90/day hire or $30–$60 buy | Kennards Hire, Coates Hire, Total Tools |
| 80-grit and 120-grit sandpaper packs | $15–$25 | Bunnings, hardware stores |
| Stiff-bristle deck scrubbing brush | $15–$30 | Hardware stores |
| Deck oil or penetrating stain (e.g. Cutek, Cabots Deck & Exterior) | $60–$120 per 4L | Bunnings, Mitre 10, Inspirations Paint |
| Paintbrush (75mm) and paint pad or roller | $15–$40 | Bunnings, Mitre 10 |
| Replacement decking boards (if needed) | $20–$50 per lineal metre (pine); $60–$120/lm (hardwood) | Bunnings, timber yards, Midland Timber |
| Decking screws (stainless steel) | $15–$40 per box | Bunnings, Mitre 10 |
| Pry bar and hammer | Own or $10–$20 hire | Total Tools, Bunnings |
Step 1: Inspect the Deck and Replace Damaged Boards
Before any cleaning or sanding, check every board for rot, splitting or movement. Push a flat-blade screwdriver firmly into the timber at each end and along the edges of boards. Solid timber offers resistance; rotted timber lets the blade sink in easily.
To replace a rotted board, use a pry bar to lever it up from the joists. If the joist below is also soft, that needs replacing first — a structurally unsound joist cannot support a new board. Cut the new board to length with a circular saw. Use stainless steel decking screws (75mm for 90mm-wide boards) to fix into each joist. Pre-drill screw holes to prevent the new board splitting.
Step 2: Clean the Deck Thoroughly
Applying oil or stain directly onto a weathered, mouldy surface is the single most common reason deck finishes fail within 6–12 months. The surface must be chemically clean and pH-neutral before any coating goes on.
Mix your timber deck cleaner (e.g. Intergrain TimberClean or Feast Watson Deck Clean) with water per the label instructions. Apply with a stiff brush, scrubbing along the grain. Leave for 10–15 minutes, then rinse thoroughly with a hose or pressure washer on low setting (no higher than 1,000 psi — higher pressure raises the grain and makes sanding harder). Leave to dry completely — allow 48 hours of dry weather minimum.
Step 3: Sand the Surface
Sanding opens the timber grain to accept the stain and removes any remaining grey surface oxidation. Start with 80-grit sandpaper, working along the grain. Follow with 120-grit for a smoother finish. Sand the full surface evenly — don’t skip the ends of boards, which weather fastest.
A random orbital sander speeds this up significantly on larger decks. Hire one from Kennards or Coates Hire for a day. For tight spots between balustrades, use a detail sander or sand by hand. Vacuum off all dust before proceeding to the stain step.
Step 4: Apply Deck Oil or Penetrating Stain
Choose the right product for your timber species. Penetrating oils (Cutek CD50, Feast Watson Decking Oil) soak into the wood and don’t form a surface film that peels — they’re the most forgiving option for Melbourne’s temperature swings. Film-forming stains give a more uniform colour but require more careful prep and re-coating every 2–3 years.
Apply the first coat generously along the grain using a wide brush or lambswool applicator. Work one or two boards at a time, keeping a wet edge. Let the first coat soak in for 20–30 minutes, then apply the second coat while the first is still slightly tacky — this is called a “wet-on-wet” application and dramatically improves penetration and longevity. Wipe off any excess that hasn’t soaked in after 30 minutes.
Step 5: Finish and Inspect
Once the final coat has dried (allow 24 hours minimum before foot traffic), inspect every board for missed spots, lap marks or areas where the grain raised during sanding. Lightly sand any rough spots with 240-grit and touch up. Apply a third coat to the most exposed areas — handrail tops, step nosings and any boards that face north or west and take direct afternoon sun.
Troubleshooting
| Problem | Cause | Fix |
|---|---|---|
| Stain peeling or flaking within 12 months | Applied over dirty or damp timber | Strip back, clean thoroughly and re-apply |
| Boards turning grey again quickly | Oil coat too thin or wrong product | Re-clean, apply heavier coat of penetrating oil |
| Raised grain after cleaning | Too much water pressure or wet sanding | Sand thoroughly with 80-grit before re-coating |
| Boards splitting after re-staining | Screws are corroding and expanding | Replace with stainless steel screws |
| Mould returning within months | Deck in shade; moisture not draining | Use mould-inhibitor additive; improve drainage around deck |
When to Call a Professional
DIY deck restoration is practical for homeowners comfortable with power tools. However, call a professional if: the structural subframe (joists, bearers, posts) shows signs of rot or termite damage — structural repairs require a licensed carpenter; the deck is elevated more than 1 metre and requires scaffolding; the deck is attached to the house and any structural modifications are needed; or if you’re in doubt about whether the timber contains asbestos or lead paint (pre-1990 properties).
Top 10 Tips and Gotchas
- Do it in autumn, not spring. Melbourne’s autumn gives mild temperatures and lower UV — ideal for timber treatments. Spring is too hot and the timber surface gets too warm for even oil penetration.
- Don’t apply in direct sun. Oil and stain applied in hot direct sunlight dry too fast and leave lap marks. Work in the shade or in the morning/evening when the deck is cool.
- Check joist condition before boarding over problems. New boards over rotted joists are a waste of money — inspect the full subframe before buying replacement timber.
- Use stainless steel screws only. Galvanised screws corrode in Melbourne’s varying humidity, leaving rust stains across your freshly stained deck. The extra cost of stainless is worth it.
- Match the board species. Spotted gum and merbau take stain very differently to treated pine. Mixing species in a repair creates an obvious patch. Source the right timber from a hardwood specialist rather than a big-box store.
- Never apply stain to damp timber. The timber’s moisture content must be below 15% (test with a moisture meter from $30 at Bunnings). Staining damp timber traps moisture inside and causes bubbling, peeling and mould.
- Recoat before grey returns, not after. Penetrating oils need recoating every 1–2 years in Melbourne. Apply the maintenance coat while the deck still looks reasonable — it only needs a light sand and one coat. Waiting until it’s grey means stripping back and starting over.
- Seal cut ends immediately. When trimming new boards, seal the cut ends with a brush coat of deck oil before fixing them down — end grain absorbs and loses moisture much faster than face grain, causing cupping and splitting.
- Leave 3–5mm gaps between boards. Timber decking expands when wet. Boards installed too tightly will buckle. If your existing boards are touching, running a circular saw blade down the joint to create a gap is the proper fix.
- Protect drains and garden beds. Deck cleaner and staining products are harmful to plants and block drains if they run off freely. Lay drop sheets and rinse the area down after cleaning.
Local Melbourne Resources
- Bunnings — Deck Oils, Stains and Timber Care
- Midland Timber — Hardwood Decking Timber Melbourne
- Kennards Hire — Sanders, Pressure Washers Melbourne
- Inspirations Paint — Deck Stain and Timber Coatings
- Mitre 10 — Decking Timber and Fixings
Frequently Asked Questions
How often should I restain my timber deck in Melbourne?
Penetrating oils typically need re-applying every 12–24 months in Melbourne’s climate depending on the deck’s exposure. Decks that face north or west, or are in full sun, need re-coating annually. Shaded decks may last 2 years between coats. The indicator is when water stops beading on the surface and starts soaking in — that’s when it’s time to re-oil.
What is the best deck oil or stain for Melbourne’s climate?
Penetrating oils like Cutek CD50, Intergrain UltraDeck or Feast Watson Decking Oil are consistently recommended on Australian DIY forums for Melbourne’s UV and temperature variation. They don’t peel, are easy to maintain, and suit most timber species including merbau, spotted gum and treated pine. Film-forming stains look more uniform but are less forgiving when it’s time to re-coat.
Can I pressure wash my deck before restaining?
Yes, but use a low-pressure setting (below 1,000 psi) and keep the nozzle at least 300mm from the surface. High pressure raises the grain, strips good timber along with the bad, and can force water into the joist connections. A dedicated timber deck cleaner used with a stiff brush gives better results for removing mould and grey oxidation than a pressure washer alone.
How do I fix cupped or warped decking boards?
Cupped boards (raised edges) are usually caused by moisture imbalance — the top dried faster than the underside, or the boards were installed too tightly. Try wetting the top surface and weighting the board flat for a few days, then restaining both top and underside. If the cupping is severe (more than 5mm), the board needs replacing. Ensure replacement boards are sealed underneath before installation.
How much does it cost to hire someone to restore a deck in Melbourne?
Professional deck restoration for a standard 20m² deck (clean, sand, two coats of oil) typically costs $600–$1,200 in Melbourne. Board replacement is priced per board on top of this. Getting the job done professionally is worthwhile if you have a large or elevated deck, or if the timber species requires careful product matching — DIY mistakes on premium hardwood are expensive to fix.
Final Thoughts
A well-maintained timber deck adds real value to a Melbourne home and lasts 20–30 years with the right care. The key is acting before the timber turns grey and brittle — a light clean and recoat costs an afternoon and $150; stripping and rebuilding costs thousands. Do the inspection now while the deck is dry, replace any soft boards, and get the oil on before the winter rain arrives.
- Replace rotted boards before coating — coating over rot never works
- Clean and sand thoroughly before applying any oil or stain
- Use penetrating oil for Melbourne’s climate — not film-forming paint
- Recoat annually or when water stops beading on the surface
