The weight of a 2-inch by 4-inch lumber board depends on its length and the type of wood from which it is made. A green-lumber 2-by-4 with a length of 8 feet weighs 13 pounds. A green-lumber 2-by-4 with a length of 12 feet weighs 20 pounds.
A pressure-treated 2-by-4 that is 8 feet long weighs 17 pounds. A pressure-treated 2-by-4 that is 12 feet long weighs 26 pounds. A 2-by-4 is a common size of dimensional lumber, which is cut to standard dimensions in inches. Dimensional lumber is typically used to frame buildings. In the United States, lumber commonly comes in lengths of 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 feet.