Both material and labor costs increase proportionally as the deck size grows. For very small decks of around 80 square feet, you may pay $2,500 to $3,500 for cheap materials, or $4,000 to $5,000 for top end woods or composites. A 10’ by 20’ deck may cost anywhere from $7,800 to $12,000. The most typical deck size picked by Americans, 300 to 350 square feet, is currently priced at $13,000 to $21,000.