Quick Answer

Composite decking in Melbourne costs $150–$350 per square metre installed, compared to $100–$200/m² for treated pine and $180–$280/m² for merbau hardwood. A 20m² composite deck costs $3,000–$7,000 in materials alone; fully installed by a professional, expect $5,500–$11,000. Composite costs more upfront but saves $200–$600/year in maintenance compared to timber.

Installing composite deck boards with hidden clip fasteners
Installing composite deck boards with hidden clip fasteners — this method leaves a clean, screw-free surface and makes future board replacement easier if one section is damaged.

Composite Decking Cost Comparison

Composite vs Timber vs Aluminium

Material Supply Cost/m² Installed Cost/m² Maintenance/Year Lifespan
Treated pine $40–$80 $100–$200 $100–$300 (oil/paint) 15–25 years
Merbau hardwood $80–$140 $180–$280 $80–$200 (oil) 25–40 years
Composite (mid-range) $80–$160 $150–$280 $0–$50 (wash) 25–30 years
Composite (premium) $150–$250 $220–$350 $0–$30 (wash) 30–40 years
Aluminium decking $180–$300 $280–$450 $0 (hose down) 40–50+ years
Pro tip: Over a 25-year period, composite decking typically costs 10–20% less than merbau when maintenance is factored in. The break-even vs treated pine is around year 8–10, assuming pine is oiled every 2 years at $300–$500/treatment.

Popular Composite Decking Brands (Melbourne Pricing)

Brand Supply Price/m² Warranty Notes
Trex (Enhance/Select) $90–$140 25–year fade/stain Most popular, US brand, widely available
Trex Transcend $140–$190 25-year fade/stain Premium capped composite, realistic wood grain
Ekodeck (Aus brand) $70–$110 25-year structural Made with Australian recycled plastics, Bunnings
TimberTech AZEK $160–$230 30-year fade/stain PVC-capped, premium end market
Futurewood (Aus) $85–$130 25-year Australian composite brand, good value
ModWood $75–$115 25-year Popular in SE Melbourne, local brand
Comparing composite deck board colours and textures before ordering
Comparing composite deck board colours and textures before ordering — getting sample boards and viewing them at different times of day in your actual outdoor space prevents the common mistake of choosing a colour that looks different in direct sun than it did in a showroom.

What Affects Composite Decking Costs in Melbourne?

1. Frame and Substructure

Composite boards need a solid substructure — either treated pine or aluminium joists and bearers. This is non-negotiable and typically costs $50–$100/m² of the total installed price. Using inadequate framing voids the product warranty. In SE Melbourne’s variable climate (hot summers, wet winters), aluminium subframes are increasingly recommended for composite decks as they don’t warp or swell.

2. Ground-Level vs Elevated Deck

A ground-level (bearer on stumps or block footings) deck costs $150–$280/m² installed. An elevated deck (300mm–1m above ground) adds $30–$60/m² for additional posts and bracing. Decks over 1m high require a building permit in most Melbourne councils and add engineering costs of $500–$1,500.

3. Fascia Boards and Edging

Matching composite fascia boards for deck edges cost $30–$80 per linear metre. A 20m² deck with 18m of perimeter adds $540–$1,440 in fascia. This is a significant visual element — match the fascia colour carefully.

4. Steps and Handrails

Each deck step costs $200–$500 installed. Handrails are required on decks over 1m high under the National Construction Code — budget $150–$350 per linear metre for composite or powder-coated aluminium handrailing.

5. Hidden Fasteners vs Screws

Hidden clip fasteners cost $5–$15/m² more than face-screwing but create a cleaner look and make future board replacement easier. Most composite deck installers now use hidden fasteners as standard for mid-range and premium products.

DIY vs Professional Installation

Composite decking is more DIY-friendly than timber in some ways (no sanding, no staining, consistent dimensions) but board cutting, hidden fastening, and subframe construction require good carpentry skills. A DIY 20m² deck saves $2,000–$4,000 in labour but takes 3–4 weekends. Most composite deck warranties require installation per manufacturer specifications — always read the technical guide before starting. Permits may be needed for elevated decks.

Signs Your Deck Needs Replacing

Problem Symptom Action
Structural bounce/flex Noticeable movement when walking, frame movement Check bearers and joists for rot — likely frame replacement needed
Composite board warping Boards lifting or cupping, visible gaps between boards Check subframe spacing — boards installed over wide joist spans warp. May be warranty claim
Mould/algae growth Green or black staining on composite surface Clean with composite deck wash ($15–$30 per bottle). Increase drainage if recurring
Fading beyond warranty Severe colour fading not covered by warranty period Check warranty — most cover 25 years. If outside, consider replacement
Frame rot (pine subframe) Soft spots underfoot, visible rot at bearers Replace subframe — often composite boards can be reused if undamaged
Safety warning: Composite decking over 1m high requires handrails under the National Construction Code (NCC 2022). Non-compliant decks are a fall hazard and a liability issue if someone is injured. Check with your council or building surveyor for local height requirements.
Measuring deck height before adding handrails
Measuring deck height before adding handrails — any deck over 1 metre above ground requires compliant balustrades and handrails under the NCC, and most Melbourne councils enforce this during final inspection.

Top Tips and Gotchas

  1. Buy 10–15% extra boards. Allow for waste from cutting (especially on angled layouts) and keep spare boards for future repairs. Colour lots change — boards from a different manufacturing batch may not match perfectly.
  2. Check joist spacing requirements. Most composite boards require maximum 450mm joist spacing (some need 400mm). Installing over 600mm pine framing (standard for timber decking) voids the warranty and causes board flex.
  3. Use stainless steel or composite-rated screws. Standard galvanised screws cause rust staining on composite boards. Use 316 stainless steel or manufacturer-recommended composite screws only.
  4. Leave expansion gaps. Composite boards expand 1–3mm per linear metre in summer heat. Leave 6mm gaps at board ends and 3–5mm between board edges (follow manufacturer specs).
  5. Composite gets HOT in summer. In Melbourne’s 40°C+ summer days, composite decking surfaces can reach 60–75°C — too hot for bare feet. Choose lighter-coloured boards (grey, light brown) over dark charcoal for sunny aspects.
  6. Aluminium subframe is worth the extra cost. Aluminium joists ($10–$20/m more than pine) won’t warp, rot, or attract termites — protecting a $5,000–$15,000 composite investment.
  7. Check for permits early. In Cardinia, Casey, and Kingston council areas, decks over 10m² or over 300mm above ground often need a permit. Apply before ordering materials.
  8. Warranty registration is mandatory. Most composite deck warranties (Trex, Ekodeck, ModWood) require online registration within 30 days of installation. Missed registration voids the warranty.
Cleaning mould growth from a composite deck with a purpose-made composite deck cleaner
Cleaning mould growth from a composite deck with a purpose-made composite deck cleaner — regular light cleaning twice a year is all composite boards need, compared to the annual oiling or painting required for timber.

FAQ

Is composite decking worth the extra cost over timber in Melbourne?

For most Melbourne homeowners who want minimal maintenance, yes. Composite’s higher upfront cost is offset by zero oiling/painting costs over its lifespan. If you’re selling within 5–7 years, the breakeven may not be reached. For long-term family homes in SE Melbourne where annual oiling is a pain, composite is generally the better investment.

How long does composite decking last in Melbourne?

Quality composite decking (capped composite from Trex, ModWood, Futurewood) lasts 25–40 years in Melbourne’s climate. The subframe (timber bearers and joists) is the limiting factor — treated pine frames typically need replacement at 15–20 years even when composite boards are still fine.

Does composite decking fade in Melbourne sun?

Early-generation composites (pre-2010) faded badly. Modern capped composites have UV-stabilised outer shells and carry 25-year fade warranties. Lighter colours (grey, sand) show fading less than dark charcoal. Annual cleaning removes surface oxidation that makes boards look washed out.

Can I install composite decking myself?

Yes, for ground-level or low-level decks. DIY saves $2,000–$4,000 in labour on a 20m² deck. You’ll need a compound mitre saw, drill/driver, hidden clip tool, and basic carpentry skills. Read the installation guide carefully — incorrect joist spacing or expansion gaps void the warranty. Decks over 1m high or requiring a permit should use a registered builder.

What’s the best composite decking brand available in Melbourne?

Trex remains the most popular with the strongest warranty (25 years) and widest installer network. ModWood and Futurewood are quality Australian brands with local distribution. Ekodeck at Bunnings is good value for budget-conscious builds. For premium pools and coastal homes (Frankston, Mornington) where durability matters most, Trex Transcend or TimberTech AZEK are worth the premium.

Local Resources

Final Thoughts

Composite decking costs $5,500–$11,000 for a typical 20m² Melbourne deck fully installed — 30–60% more than treated pine but with essentially zero ongoing maintenance. For SE Melbourne homeowners who don’t want to spend every summer oiling or painting, composite is a clear winner. Choose a capped composite product with a 25+ year warranty, use an aluminium subframe for longevity, and confirm council permit requirements before starting. The investment adds genuine value to Melbourne homes.