The Most Accurate Ways To Get Measurements For A Roof Replacement


Before you attempt to replace your roof, it’s important to take measurements so you can buy the correct materials. This will not only save you time in having all the right materials to do the job, but it will also save you money in the long run. Will a little bit of patience and some basic geometry, you can complete the job with just a calculator, a ladder, a carpenter’s level, and a measuring tape.

Create a Rough Sketch

With a rough sketch of the roof, you will have a useful tool that gives you accurate measurements to avoid any confusion. When making your rough sketch of the roof, make sure to include all parts of the roof including the ridge, hip, valley, and rake. Also remember to include solar panels, skylights, chimneys, vents, and pipes. Try to draw it as proportionally as you can, but don’t worry if it is not exactly drawn to scale. Don’t forget to also include diagonal, horizontal, and vertical measurements on your sketch to accurately estimate how much roof materials you will really need.

Slope Measurements

You will save a lot of time if you first measure the slope. An inclinometer is needed to measure the angles or the inclination of the roof. This is a cheap but useful instrument that can measure the inclination of an object by using gravity to measure the slope. An inclinometer is also called a gradient meter, slope indicator, slope gauge or a tilt meter.


Since a roof can be constructed in a wide range of shapes, it is important to measure all of the slopes in the inclined areas when calculating the area of the roof. You can easily divide up the roof into different shapes like rectangles, squares, and triangles to make the calculations of the area easier. Calculating the different slopes will help you to calculate the total area of all the different shapes.

Taking the Measurements

The measuring wheel is the most common most tool used to measure the various parts of the roof. With this tool, your work is faster and easier since it does not require having someone else hold the other side of the tape. Since this is a mechanical device, it is imperative to make sure that it is working correctly before you use it.

For those of you that aren’t comfortable using a measuring wheel, you can use a flat measuring tool like a measuring tape. Keep in mind that this will take a lot more time to measure all the different areas of the roof than if you used a measuring wheel. A measuring tape is also a lot less precise than a measuring wheel.

Calculating the Area

After taking all the measurements, you are ready to calculate the area of the roof by using the following steps:

  • Divide the roof into triangular and rectangular sections.
  • Don’t worry if your roof seems to complex. It is always possible to break down the roof into sections of squares, rectangles, and triangles.
  • It is helpful to number these sections making them easier to remember.
  • When determining the area of a rectangle, multiply the width by the length. This is the easiest section to calculate.
  • Next, divide up the remaining areas into triangles and use the basic triangle area formula of ½ the base times the height, or the distance between the peak and the base.
  • Finally, add the areas of all the sections together to get your overall roof area.

Satellite Roof Measurements

Another option that you may want to consider is getting an app that does roof measurements from a satellite. This type of tool allows you to stay on the ground while obtaining necessary roof measurements preventing personal injury. With the high-resolution images, you can also inspect the condition of your roof and find out where there are shingles that are damaged. Satellite roof measurements are a time-saving tool that helps you figure out the measurements faster so you can get your roof replaced before it is damaged further.

Shingle Calculation

After figuring out the calculations for the different areas, you have one more step. To accurately estimate the amount of material needed, you need to figure out how many shingles are required. When estimating the number of shingles you will need, just add the linear feet found at the eave and then divide it by the length of just one shingle. Since shingles come in several different shapes, make sure you know the type of shingle you plant to use before you make the calculation.

Here are a few important things to remember out shingle shapes:

There are two types of shingles, either three-tab shingles or pre-cut shingles. You can use either, just keep in mind they won’t give you the same coverage. You will only get about 33 linear feet of ridge or hip coverage with three-tab shingles while you get a lot more coverage with pre-cut shingles.

You can get some shingles in a bundle of three per square and some in four or more per square. Keep in mind it is better to use fewer bundles. Pick up extra shingles in case you run short. Just make sure to keep them in a place where they won’t get damaged so you can return them if they aren’t used.

Here in the United States, you can usually buy a bundle of shingles that will cover 100 square feet so all you need to do is divide the overall area of the roof by 100. This will easily give you the number of shingles required for your roof.

Keep in mind that your entire roof measurement includes four different parts. You will need to measure the slope, measure the roof, calculate the area, and calculate the number of shingles you will need. Remember, you will need a lot of patience to achieve the most accurate calculation to get the correct number of shingles and other materials.

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