Sketch each side of your house on a separate piece of paper, drawing in the squares, rectangles and triangles that make up each section of your house.
Measure the length and width of each rectangle or square, rounding off each number to the next whole number.
Write those numbers onto your sketched diagram corresponding with the area measured.
Multiply the length and width of each section to find out the square footage needed to cover that section.
Measure each triangle.
Write down the base measurement and the height, rounding off the each number to the nearest whole number. Jot these numbers onto your sketched diagram, corresponding with the areas just measured.
Calculate the square footage needed for each triangle by multiplying the base and the height.
Write the square footage needed for each section in the corresponding section of the diagram.
Add up all the measurements that you calculated for each triangle, square and rectangle. This gives you the total square footage needed for siding.