Pressure-treated lumber is one of the best options that you can use for a roof deck because of its extreme durability. If you are constructing a roof deck, you will need to be concerned with the amount of water that gets on the wood. Pressure-treated wood already has a built-in water resistance. Furthermore, this type of wood is not susceptible to insect damage or rot. While pressure-treated wood might be a little more expensive than standard lumber, it is generally well worth the investment that you would have to make.