Composite vs timber decking: what it actually costs
Board prices, cost per square metre, and the whole-deck numbers for the same 17 m² deck built two ways.
Almost every "composite vs timber" article compares a headline board price and stops there. That is the least useful number available: boards come in different widths, so a cheaper board can easily cost more per square metre of finished deck, and the subframe underneath is the same money either way.
The tables below are generated from the product data this site prices decks with, so they move when the feed moves rather than when someone remembers to edit an article.
Board prices, per square metre of deck
Cost per square metre is the number that survives a change of board width. It assumes boards laid with the 5 mm gap the configurator uses by default, so each board covers its own width plus one gap.
| Product | Size | Supplier | Per board | Per m² of deck |
|---|---|---|---|---|
| Cladco Composite — Charcoal | 3600 × 150 × 25 mm | Travis Perkins | £29.34 | £52.58 |
| Cladco Composite — Coffee | 3600 × 150 × 25 mm | Travis Perkins | £29.34 | £52.58 |
| Cladco Composite — Stone Grey | 3600 × 150 × 25 mm | Travis Perkins | £29.34 | £52.58 |
| Cladco Composite — Teak | 3600 × 150 × 25 mm | Travis Perkins | £29.34 | £52.58 |
| Hardwood Balau | 1800 × 90 × 19 mm | Russwood | £29.99 | £175.38 |
| Hardwood Balau | 2700 × 90 × 19 mm | Russwood | £42.99 | £167.60 |
| Hardwood Balau | 3600 × 90 × 19 mm | Russwood | £55.99 | £163.71 |
| Pressure Treated Softwood | 3000 × 124 × 29 mm | Travis Perkins | £8.50 | £21.96 |
| Pressure Treated Softwood | 3600 × 124 × 29 mm | Travis Perkins | £10.19 | £21.94 |
| Pressure Treated Softwood | 4800 × 124 × 29 mm | Travis Perkins | £13.84 | £22.35 |
Two things usually surprise people here. Composite is not the most expensive option on the board line — hardwood often is. And the cheapest board per length is rarely the cheapest per square metre, because narrow boards need more of them.
The same deck, both ways
Board price is roughly half the story. A deck also needs joists, bearers, posts, edging and fixings, and those are identical whichever surface you choose. Here is one 4.8 × 3.6 m deck — 17.3 m² — specified twice. Open each one and the solver plans the real board layout, the cutting list, and the subframe, then prices the lot.
4.8 × 3.6 m in Cladco composite
Composite boards on C16 joists at 400 mm centres, with matching composite edging.
Open this deck in the configuratorThe same deck in pressure-treated softwood
Identical footprint, joists and centres — only the board and edging change.
Open this deck in the configuratorChange the footprint on either one and both numbers move with it. That is the honest way to compare: the difference between two decks you would actually build, not two board prices.
What the board price does not tell you
- Waste. Stock lengths rarely divide neatly into your deck. A 4.8 m deck run in 4.0 m composite boards leaves a lot of offcut; the same run in 4.8 m timber leaves almost none. The solver reports the waste for each option, and it can be worth more than the price difference per board.
- Fixings. Composite systems often use hidden clips at a fixed rate per square metre; timber decks are usually face-screwed. Both are in the bill of materials.
- Joist centres. Most composite boards want 400 mm centres or tighter, where 32 mm softwood will happily sit at 500 mm. Tighter centres means more joists — a subframe cost that follows from the board choice.
- Maintenance. Not a materials cost, so it is not in any of these numbers, but it is the usual reason people pay more up front for composite.
How to use this
Draw your actual deck rather than reading a table for a deck you are not building. Set the footprint, pick a board, and let it price; then swap the board family and watch the total move. Everything reprices live, so a comparison takes seconds.
Plan your deck · Millboard range guide · Joist spans explained