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  • Matt O'Dore

How to Measure the Size of Your Roof for Free


Man measuring roof

Before you can replace your roof, you need to know how big it is. You might think that measuring the size of your roof is a daunting task, but not anymore. The days of roofers in Vancouver, WA using a ladder, tape measure, calculator, and notepad are ancient times as we introduce to you the easiest and cheapest way to measure your roof.

Tools You'll Need:

  • Your phone

  • That's it.

Seriously, a phone is all you need in order to measure your home's roof. While this method doesn't work for all houses and requires you to have the technical skills to navigate your smartphone, most people should be able to follow these instructions to find the size of their roof within a 5% margin of error.

Step 1: Download the Necessary Apps

  1. Calculator

  2. Google Earth (Apple) or Google Earth (Android)

  3. Pitch Gauge (Apple) or Pitch Gauge (Android)

Your phone will already have the calculator app and likely Google Earth as well but what is a pitch gauge app? It's an app that allows you to figure out how steep your roof is which we will need to know to determine the overall size. For a pitch gauge app feel free to download one with good reviews from whichever app store you use.

Step 2: Find the Area of Your Roof

To find the area of your roof you need to open the Google Earth app and type in your address. Once you are zoomed in over your house, click the ruler icon. This will now allow you to begin to measure the your roof. drag the image around and click on each corner of your roof until the entire structure is outlined. This will now tell you the area of your roof in square feet as if it were flat. It's not actually flat so that's where we save this number and move on to the next step.

Step 3: Find the Pitch of Your Roof

What is roof pitch?

The pitch of your roof is determined by how much it slopes. This is always calculated as a fraction of 12. Most homes are between 4/12 and 8/12 pitch. with a 4/12 roof, if you held a 12 inch ruler level with the ground where one edge is touching the roof and the other is pointed toward the gutter, the edge of ruler should be 4 inches off the roof.

How do I find it?

Easy, with an app. Open your pitch gauge app. Notice that as you change the level of your phone it will change the number on the screen. Either place your phone on top of the roof or on a piece of trim underneath the eave with the same slope and look at the number on your phone and save it.

Step 3: Easy Math

Now that you have all of your measurements, it's time to do some math! To calculate the square footage of your roof we first need to convert the pitch of your roof into a multiplier with a roof pitch factor chart. Find the number on the chart that matches the pitch of your roof and type that into your calculator. This number is how many times bigger your roof is than if it were flat. Multiply this number by the square footage of your home from your measurement on Google Earth.

Pitch

Multiplier

1/12

1.003

2/12

1.014

3/12

1.031

4/12

1.054

5/12

1.083

6/12

1.118

7/12

1.158

8/12

1.202

9/12

1.250

10/12

1.302

11/12

1.357

12/12

1.414

13/12

1.474

14/12

1.537

15/12

1.601

16/12

1.667

17/12

1.734

18/12

1.803


All done? Possibly! If you have a simple roof without any hips or valleys, this number should be very accurate. But what if your roof is very cut up and has many different facets? A quick and easy way to increase your final number by an additional 2% for each gable or hip. This isn't an exact science but it will get you as close as you need to be.

Need an estimate on replacing your roof in Vancouver, WA? Give Matador Exteriors a call today and our roofers in Vancouver, WA will do all of the measuring for you!

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