How do you calculate the amount of dimensional lumber for a 20X28 foot cabin?

To calculate the amount of dimensional lumber for a 20x28 foot cabin, first determine the total square footage of the walls, roof, and floor. For walls, multiply the perimeter (2*(20+28)) by the height, subtracting for Windows and doors if applicable. For the roof, calculate the area based on the roof pitch and include any overhang. Finally, convert the total area into board feet based on the dimensions of the lumber you plan to use, considering the standard 1, 2, or 3-inch thicknesses.