Composite vs. Wood Decking: What Changes in the Math
How composite and pressure-treated wood decking compare on cost, lifespan, and maintenance, and how board width affects your material count.
Composite and wood decking aren't just a style choice — they have real differences in cost, lifespan, and even the board sizes you'll plug into a material calculator.
| Pressure-treated wood | Composite | |
|---|---|---|
| Upfront material cost | Lower | Higher — often 2-3x wood |
| Lifespan | 10-15 years with maintenance | 25-30 years, minimal maintenance |
| Maintenance | Annual staining/sealing recommended | Occasional cleaning only |
| Common actual width | 5.5" (1x6) or 3.5" (1x4) | Often 5.25"-5.5", varies by brand |
| Joist spacing | 16" o.c. typical | Often requires 12" o.c. — check span rating |
Why joist spacing can differ
Composite boards flex differently than solid wood, and many composite manufacturers require tighter joist spacing (commonly 12 inches on center instead of 16) to prevent sagging between joists over time — always check your specific product's span rating rather than assuming standard wood spacing applies.
The long-term cost picture
Wood costs less upfront but needs recurring maintenance and replacement sooner; composite costs more upfront but spreads that cost over a much longer lifespan with less ongoing labor. Which is cheaper depends on how long you plan to own the property.
Run either material's actual board width and joist spacing through the Deck Material Calculator to compare real material counts for your deck's dimensions.