The main factor that affects the cost of a new deck is the material it's made out of. As of 2015, a pressure-treated wood deck can be as little as $15 per square foot, while a deck made with premium wood or composite materials can run upwards of $35 per square foot.
Some other factors that affect the price of a new deck are if stairs are needed or if the wood needs to be stained or painted. Waterproofing, sealing and blocking UV rays also factor into the price.
In addition to the costs of labor and materials, a deck adds to the size of the house, which means owners have to pay more in property taxes. A home insurer may want the homeowner to take out extra coverage on the deck, and getting building permits before construction can also cost money.