Pressure-treated lumber is cheaper upfront, while composite costs more to install but saves money over its lifetime. Across a typical 20-year span, the regular cleaning and sealing that wood needs can erase most of its head start, so the "cheaper" board depends entirely on how long you plan to keep the deck.
Before you compare prices, get your real material quantity. Plug your dimensions into the deck board calculator so you're pricing a solid estimate of the boards you'll buy, not a rough guess.
The upfront numbers
Per square foot of installed deck surface, pressure-treated boards are the budget option. They cost noticeably less than composite for the boards alone, and most homeowners already know how to work with wood, which keeps labor down on a DIY build.
Composite boards carry a higher sticker price. You're paying for a wood-plastic blend that won't rot, splinter, or feed mold the way lumber can. The premium is real, and on a large deck it adds up fast.
A few things shift the math on both sides:
- Board count. A bigger or oddly shaped deck multiplies the per-board difference. See standard deck board sizes to choose lengths that minimize waste.
- Waste factor. Add 10% for a straight layout and 15% for diagonal or picture-frame designs. That extra material costs more in composite.
- Fasteners. Composite often uses hidden deck fasteners, which look clean but add to the per-square-foot total.
The cost wood hides
The pressure-treated price tag isn't the whole story. Wet treated lumber arrives heavy with moisture and shrinks as it dries, which is why it needs a tighter installation gap and, later, attention. To keep a wood deck looking good and lasting, plan on:
- Cleaning once or twice a year
- Re-staining or re-sealing every two to three years
- Replacing the occasional cracked, cupped, or rotted board
None of that is expensive in a single year, but it recurs for the life of the deck. Stain, sealer, a pump sprayer, and a weekend of your time, every few years, for two decades. That's the line item people forget when they crown wood the cheaper choice.
The 20-year view
Here's the honest comparison. Composite is dimensionally stable and low-maintenance: an occasional wash with soap and water is usually all it asks, and it doesn't need staining. Over a long ownership horizon, those skipped maintenance cycles add up.
So the rule of thumb breaks down like this:
- Short hold (under ~7 years). Pressure-treated almost always wins. You capture the low upfront cost and bail before too many maintenance cycles hit.
- Long hold (~15-20+ years). Composite frequently comes out ahead once you total every can of sealer and weekend of labor you avoided.
- The middle. It's genuinely close, and the tiebreaker is how much you value your weekends.
If you'd rather spend Saturdays on your deck than maintaining it, composite is buying back your time as much as your money.
Beyond the dollars
Cost isn't the only axis. Pressure-treated wood feels and looks like real wood because it is, and it's easy to cut, repair, and source anywhere. Composite resists splinters and stays cooler underfoot in some product lines, holds its color, and won't rot at ground contact.
Spacing differs too, which affects your build. Wet treated boards shrink, so you gap them tighter (around 1/8 inch). Composite is stable and follows the manufacturer's exact spacing. Our guide on how to space deck boards walks through both.
The bottom line
Buy pressure-treated if your budget is tight today or you won't keep the deck long. Buy composite if you're staying put, you hate maintenance, or you want a 20-year cost that likely beats wood once upkeep is counted. Either way, run your real board count through the deck board calculator first, so you're comparing reliable planning totals instead of marketing numbers. Measure twice. Buy once.