What drives deck cost
Material is the biggest swing: pressure-treated lumber is cheapest, cedar is mid-range, and composite (Trex-style) costs the most but lasts longest with little upkeep. Height, railings, stairs, and footings all add up too — a raised deck with stairs costs far more per square foot than a simple ground-level platform. Use the per-square-foot price that matches your material and whether you're hiring out the labour.