Composite vs Pressure-Treated Decking
Pressure-treated lumber costs a fraction of composite per square foot and asks for a weekend of maintenance every two or three years. Composite costs more once and asks for a wash. The break-even sits somewhere around ten years, which means the honest answer depends less on the boards than on how long you intend to own the deck.
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- 12x16 Deck Cost Calculator — material list and cost for a 12 by 16 foot deck
- Deck Board & Joist Calculator — board count, joist count and framing for a deck
| Pressure-treated | Composite | |
|---|---|---|
| Up-front material cost | Lowest of any decking | Two to four times treated lumber |
| Maintenance | Clean, sand and re-seal every 2–3 years | Wash annually; no sealing |
| Service life | 10–15 years, longer if maintained well | 25–30 years, warranties commonly 25 years+ |
| Surface heat | Cooler underfoot in direct sun | Noticeably hotter, especially dark colours |
| Joist spacing | 16 in. on centre standard | Often 16 in., 12 in. for diagonal or some brands |
| Scratches and stains | Sands out | Permanent — capped boards resist but do not repair |
| Fasteners | Deck screws, face-fixed | Hidden clips on grooved boards; adds real cost |
| Appearance over time | Greys unless sealed; can be restained any colour | Holds colour; slight fade in the first year |
| Best for | Tight budget, short horizon, DIY replacement | Long ownership, low maintenance tolerance |
What the price difference really buys
Composite is not simply a nicer board — it is a different maintenance contract. Treated lumber that is never sealed does not fall apart, but it greys, checks along the grain and grows splinters at the edges within a few seasons, and the boards that face the weather worst usually need replacing before the frame does. The maintenance cost is real even when it is paid in weekends rather than dollars.
Composite removes that entirely and replaces it with a fixed decision made once. What it does not remove is the frame: the joists, beam and posts underneath are pressure-treated lumber either way, and they are what the deck is actually standing on. Buying composite boards does not buy a longer-lived structure, only a longer-lived surface.
The differences that show up on site
Heat is the complaint that surprises people. A dark composite deck in full afternoon sun gets hot enough to be uncomfortable barefoot in a way treated lumber does not. If the deck faces south and gets used by children or dogs, choose a light colour or accept it.
Span matters if you are re-decking an existing frame. Some composite boards want joists at 12 inches on centre rather than 16, and every composite board requires closer spacing when laid diagonally. Finding that out after the old boards are off is an expensive surprise, so check the manufacturer span table before you buy.
Scratches are permanent. A capped composite board resists staining and fading well, but a dragged planter or a dog with enthusiasm leaves a mark that cannot be sanded out — the cap is the wearing surface. Treated lumber, by contrast, sands and restains as often as you like.
Where the money actually goes
On a treated deck, boards and framing are roughly comparable and fasteners are a rounding error. On a composite deck, the boards dominate and the hidden fastener system becomes a line worth pricing separately — grooved boards with clips can add a meaningful amount over a large area compared with a box of screws.
Labour barely differs. Composite is not much slower to install, so hiring the work out does not change the comparison; it just raises both totals by a similar amount. Price both options through the same deck calculator with your real dimensions rather than trusting a per-square-foot average, because the ratio between them shifts with deck size.
Result
Keeping the house and the deck for more than ten years, or unwilling to re-seal on a schedule: buy composite, in a light colour, and check its joist spacing before ordering. Building on a tight budget, planning to move, or comfortable with a weekend of maintenance every couple of years: pressure-treated is the rational choice and always has been. In both cases the frame is treated lumber, so the decision is only about the surface.
Common questions
- Is composite decking cheaper over 20 years?
- Usually yes, once staining and board replacement are counted. Break-even is commonly around the ten-year mark; past that composite pulls ahead, and it does so faster the more you would have paid someone else to maintain the wood.
- Can I put composite boards on an existing treated frame?
- Often, but check two things first: the joist spacing the boards require, and the condition of the frame. Re-decking a frame that has five years left in it wastes a surface with twenty-five.
- Does composite get too hot to walk on?
- Dark boards in direct sun get considerably hotter than wood. Light colours are markedly better, and shade or a rug solves the rest.
In this topic
- Deck Cost Calculators
- What Does a Deck Cost Per Square Foot?
Why the per-square-foot number ranges so widely, which half of the budget actually moves, and what changes when the deck gets taller rather than wider.
- Guides
Updated 09/03/2026