Composite decking costs roughly two to three times pressure-treated per square foot. Over twenty years the gap narrows, and whether it closes depends on one assumption most comparisons hide: whether you would actually have maintained the wood.
Year one, 200 ft² deck surface
| Pressure-treated | Composite (mid) | |
|---|---|---|
| Boards | $600 | $1,600 |
| Fasteners | $60 | $250 (hidden clips) |
| Labor | similar | similar |
| Stain, year one | $150 | — |
| Material total | $810 | $1,850 |
Composite starts about $1,000 ahead on a small deck. On a 400 ft² deck it starts about $2,000 ahead.
Twenty years, if the wood is maintained properly
Pressure-treated needs cleaning and re-staining roughly every two to three years. Call it eight cycles in twenty years.
- Materials per cycle: $120–$200 for cleaner and stain
- Time per cycle: a full weekend for 200 ft², including drying between coats
- Eight cycles: $1,200 in material, and sixteen days of your weekends
If you hire it out, deck cleaning and staining runs $2–$5 per ft² — $400 to $1,000 per cycle, so $3,200 to $8,000 over twenty years.
| Twenty-year total, 200 ft² | PT, DIY finish | PT, hired finish | Composite |
|---|---|---|---|
| Boards and fasteners | $660 | $660 | $1,850 |
| Finishing | $1,200 | $5,600 | $0 |
| Board replacement | ~$200 | ~$200 | $0 |
| Total | ~$2,060 | ~$6,460 | ~$1,850 |
Hired maintenance makes composite obviously cheaper. DIY maintenance makes them about level in money, and the difference becomes sixteen weekends.
The assumption that decides it
Most pressure-treated decks are not refinished on schedule. They get stained once, maybe twice, and then they go grey and splinter, and at year fifteen the boards get replaced.
If that is the honest forecast, the real comparison is:
- PT: $660 boards, one or two stains, full board replacement at year 15 — around $700 more in materials and a weekend of demolition
- Composite: $1,850 boards, nothing
On that basis composite wins on cost as well as on effort. Which is the actual reason it took over the market, not the brochure.
Where composite is the wrong answer
Very large decks. The up-front gap scales linearly. On an 800 ft² deck the difference is $4,000 or more at the start, and that is real money now against savings spread over two decades.
Hot, sun-exposed decks. Composite gets hotter underfoot than wood — noticeably so on dark colours in full sun. Light colours help; the physics does not go away. Test a sample board in the sun before choosing a colour.
Low decks with poor ventilation. Composite expands and contracts more than wood along its length and needs the manufacturer's end gaps honoured. A deck built tight in December buckles in July.
Structural pieces. Composite is a surface, never a joist, beam, post or stair stringer — and stair stringers in particular are cut from 2×12 pressure-treated whatever the deck surface is. Those are pressure-treated regardless of what the deck surface is, so a "composite deck" is always a wood-framed deck.
What both share
The frame. Joists, beams, posts and ledger are pressure-treated in both cases, and the framing is where the deck's life is decided, not the surface.
A composite surface on an undersized frame is a bouncy deck with an expensive floor. Spacing matters more for composite too — most brands require 16″ on center for straight layouts and 12″ for 45° diagonal, which is a framing cost that arrives with the decking decision.
Board counts and fastener counts for either material come out the same way; only the price per board changes.