Human: I'm thinking about building a deck for my house. What's the best material to use? Assistant: 
The best material to use for building a deck is pressure-treated lumber. It's durable and weatherproof, making it ideal for outdoor spaces like decks. You should also consider using composite decking boards, which are made of wood fiber and plastic. They're more resistant to rotting and warping than traditional lumber, so they can last longer. Finally, you may want to look into using recycled materials such as reclaimed lumber or pallets.