Based on over 7,000 user-submitted cost profiles on HomeAdvisor.com, the average cost of building an outdoor deck as of 2015 is between about $4,000 and $10,000. Total costs vary greatly depending on the size of the deck, the type of building material and the complexity of the design.
The 2015 cost averages on HomeAdvisor.com range from about $5,000 for decks smaller than 200 square feet to about $14,500 for decks larger than 500 square feet. Building materials play a key role in determining total cost; some common deck materials include composite woods, natural hardwoods and pressure-treated woods. Besides the materials themselves, other factors that affect the total cost of building a deck are the design and the labor. Do-it-yourself projects are typically much cheaper, though homeowners may lack the time or skill to complete the project, especially for more elaborate designs.