Why Is Composite Decking So Expensive?
Composite decking is quite expensive due to its complex manufacturing process and the cost of high-quality raw materials. Although the initial investment is high, it essentially eliminates the costly and time-consuming maintenance associated with traditional wood and offers a longer lifespan. Therefore, it is an investment with long-term value.
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Why Composite Costs More?
Composite decking is not just wood with plastic mixed in. The manufacturing process is complex, and that complexity drives the price.
Raw Material Processing
Composite boards are made from recycled wood fibres and recycled HDPE plastic. Both materials must be cleaned, sorted, and processed before they can be blended. Recycled plastic in particular requires extensive washing and pelletising to remove contaminants. This processing adds cost that does not exist for sawn timber.
Co-extrusion Technology
Higher quality composites (including EVODEK boards) use a process called co-extrusion. The core material is extruded through a mould while a separate polymer cap layer is simultaneously bonded around all four sides. This cap layer provides UV resistance, stain resistance, and moisture protection. The dual extrusion process requires specialised machinery and precise temperature control, which adds to the manufacturing cost.
EVODEK boards are produced at a density of 1.3 g/cm³ using dual screw co-extrusion. This is denser than most competing composites, which means more raw material per board and a higher production cost, but also better scratch resistance and less flex underfoot.
Testing and Certification
Quality composite products undergo testing for slip resistance, fire resistance, UV stability, and structural load capacity. EVODEK boards are FSC certified (verifying responsible sourcing of wood fibre) and tested under Australian conditions. These certifications cost money to obtain and maintain, and that cost is reflected in the product price.
Warranty Coverage
EVODEK offers a 25 year residential warranty (10 year commercial). A warranty this long means the manufacturer is financially backing the product’s performance over decades. The cost of honouring warranty claims is factored into the product price. Timber products rarely carry warranties beyond 5 to 10 years, so this long-term commitment is a genuine differentiator.
The Real Comparison: Cost Over 25 Years
Comparing only the upfront price is like comparing a car’s purchase price without considering fuel, servicing, and repairs. The total cost of ownership tells the real story.
Upfront Cost (Materials Only, per Square Metre)
| Material | AUD per sqm |
|---|---|
| Treated Pine | $30 to $60 |
| Merbau | $60 to $100 |
| Spotted Gum or Blackbutt | $90 to $140 |
| Composite (standard) | $60 to $100 |
| Composite (co-extruded, premium) | $100 to $160 |
At the material level, composite sits in the same range as mid to high end hardwood. It is significantly more expensive than treated pine.
Annual Maintenance Cost
| Material | What is needed | Annual cost (25 sqm deck) |
|---|---|---|
| Treated Pine | Sand, stain, seal every 1 to 2 years | AUD $200 to $500 |
| Merbau or Spotted Gum | Oil every 1 to 2 years | AUD $150 to $300 |
| Composite | Wash with soapy water once or twice a year | AUD $0 to $50 |
Timber maintenance is not optional. Without it, treated pine rots within 8 to 10 years. Hardwood weathers to grey and develops surface cracks. The time commitment is also significant: sanding, staining, and sealing a 25 sqm deck takes a full weekend.
25 Year Total Cost of Ownership (25 sqm Deck, Installed)
| Scenario | Initial build | Maintenance (25 yrs) | Mid-life replacement | 25 year total |
|---|---|---|---|---|
| Treated Pine (replace at year 12) | AUD $6,000 | AUD $6,000 | AUD $6,000 | approx. AUD $18,000 |
| Merbau (one build, maintain) | AUD $10,000 | AUD $5,000 | none | approx. AUD $15,000 |
| Composite (one build, minimal care) | AUD $14,000 | AUD $500 | none | approx. AUD $14,500 |
Over 25 years, composite delivers the lowest total cost. The higher upfront price is offset by near zero maintenance and no mid-life replacement.
This calculation assumes the subframe is built correctly with H3/H4 treated pine and joist flashing tape to match the board lifespan.
When Timber Is the Better Choice
Of course, composite decks aren’t for everyone. If any of the following apply, wood might be a better choice.
Short-term Use
If you are building a deck for a rental property, a home you plan to sell within 5 years, or a temporary outdoor entertaining area, treated pine delivers the lowest upfront cost. The long term savings of composite do not apply if you will not be around to benefit from them.
Budget Constraints
If your total budget for a deck project is under AUD $5,000, composite may not be achievable for a meaningful deck size. Treated pine allows you to build a larger deck within a tighter budget.
Natural Timber Preference
Some homeowners prefer the look, smell, and feel of real wood. Composite has improved significantly in appearance, but it is not identical to natural hardwood grain. If authentic timber character is your priority, hardwood (Merbau, Spotted Gum, Blackbutt) is the right choice, and the maintenance trade-off is worth it.
Cold Climate Comfort
In cooler regions like Tasmania, the ACT, and highland areas, timber surfaces stay more comfortable underfoot than composite in winter. Composite can feel cold to bare feet in low temperatures.
What Affects the Total Price of a Composite Deck?
Deck Size
Larger decks cost more in total but often less per square metre. Builders work more efficiently on bigger, simpler areas. Use the EVODEK Decking Calculator to estimate material quantities for your deck dimensions.
Subframe Material
The subframe (joists, bearers, posts) sits underneath the boards and carries all the structural load. H3/H4 treated pine is the most common and affordable subframe material. Aluminium and steel subframes cost 40% to 60% more but last longer and resist rot entirely.
Board Profile
Hollow core composite boards cost less than solid core boards. They are lighter and use less material. Solid core boards are denser, feel more rigid underfoot, and resist impact better. Co-extruded boards with a protective cap layer sit at the top of the price range but offer the best UV and moisture protection.
Labour
Professional deck installation in Australia typically costs AUD $40 to $80 per square metre for board laying, plus AUD $80 to $200 per square metre for the subframe (footings, posts, bearers, joists). For a 25 sqm composite deck, expect total labour costs of AUD $3,000 to $7,000 depending on site complexity, height, and access.
DIY installation can reduce costs significantly. However, structural work (footings, bearers, joists) should be done by a licensed builder if you are not confident with framing.
Railings, Stairs, and Extras
Do not forget the extras. Deck railings add AUD $150 to $400 per linear metre. Stairs add AUD $1,000 to $2,500 per set. Deck lighting adds AUD $300 to $1,500. Privacy screens add AUD $100 to $300 per linear metre. These items can add 20% to 40% to the total project cost.
Summary
Composite decking is more expensive at the point of purchase. That is undeniable. But the reasons behind the higher price (complex manufacturing, recycled material processing, co-extrusion technology, rigorous testing, and long term warranty coverage) translate directly into a product that lasts longer, costs less to maintain, and delivers a lower total cost over its lifespan.
For most Australian homeowners who plan to enjoy their deck for a decade or more, composite is the more cost effective choice when measured over the full ownership period.
Frequently Asked Questions
Why is composite decking more expensive than treated pine?
Composite manufacturing involves processing recycled plastics and wood fibres, blending them under heat and pressure, and (for premium products) co-extruding a protective cap layer. This multi-step process costs more than sawing and chemically treating pine logs. The result is a board that resists rot, insects, moisture, and UV without any ongoing treatment.
Is composite decking worth the extra cost?
For homeowners who plan to stay in their home for 10 years or more, yes. The 25 year total cost of ownership for composite is comparable to or lower than timber when you factor in maintenance, repairs, and mid-life replacement. For short term projects or very tight budgets, timber may be more practical.
How much does a composite deck cost in Australia?
A fully installed composite deck (including subframe, boards, and basic finishing) costs approximately AUD $300 to $600 per square metre. A typical 25 sqm deck runs AUD $7,500 to $15,000 for materials and AUD $3,000 to $7,000 for labour. Costs vary by region, site conditions, and product choice.
Can I save money by installing composite decking myself?
Yes. DIY installation can save AUD $3,000 to $7,000 in labour on a typical residential deck. Board laying with hidden clip systems is within reach for a handy homeowner. However, the subframe (footings, posts, bearers, joists) is structural work that affects safety. If you are not experienced with framing, hire a professional for the subframe and lay the boards yourself.
Does waterproofing the deck add to the cost?
For composite decking, the board surface does not need any waterproofing treatment. The co-extruded cap layer handles moisture protection. However, the timber subframe underneath should be protected with joist flashing tape (AUD $30 to $60 per roll). This small investment can add years to the subframe’s life, especially in high rainfall areas.
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