If you are reading this article, chances are that you are about to put a new roof over your building and you need to know the materials that you will need for the roof or create a budget for the roofing project. To do this, you need to measure your roof and know its area. You will need to have an understanding of basic geometry to measure your roof and get an accurate calculation. Follow the steps below to measure your roof.

  • Sketch Your Roof

For roofs that are not simple or typical triangular roofs, a sketch is recommended. You should include everything that will go on the roof in the sketch, such as chimneys, skylights, pipes trim etc. When you create a sketch, it is easier for you to mark your measurements.

Bryan from MapleTree Roofing states that “You should make your sketch taking into account the different parts of the roof.” It is advised that you sketch the different parts with different colours. Below is a simple colour key you can use:

      • Green for the ridge cap
      • Blue for the drip edge or eave edge
      • Red for the valley of the roof
      • Purple for the rake edge


  • Measure The Roof

To start, you will need to understand the process of measuring a simple right angle triangular roof with no extra features on it. The formula used would be that of getting the area of a triangle which is its length multiplied by its height and the result of that divided by 2.

If the length of the roof is 40 feet and the height is 15 feet, the area would be (40*15)/2 which is 300 square feet. One roof square is equal to 100 square feet, so this would mean that the area of your roof is 3 roof squares.

For more complex roofs, you would have to break up the sketch you have made into sections of rectangles and triangles. For example, the above diagram showing the different parts of a roof would still be broken down into a triangle and a rectangle. You will do the same thing across the entire roof then you will measure out the roof portions according to your divisions. Note that the formula for getting the area of a rectangle is its length multiplied by the breadth.

Once you have calculated the areas for each portion, you are to add them up to give you the sum total of your roof’s area. Remember to mark all the measurements you have made on the sketch you drew up.

  • Measure All The Others Parts Of Your Roof

This includes pipe measurements (all the pipes that go through the roof must be measured), valley lengths, amount of side wall, end wall and transition pieces. You need to measure all these parts so that you can have an accurate measurement and all that is required for your roofing project.

Once you have done all of this you will have an accurate measurement of your roof. If the roof is really complex, then get in experts to survey your roof.