How to Measure a Roof with Google Earth
Roof Online Staff
Table of Contents
- How to Measure a Roof with Google Earth
- 1. Download and Install Google Earth
- 2. Open Google Earth
- 3. Uncheck “3D Buildings” Box
- 4. Search for the Address of the Building
- 5. Zoom in on the Roof
- 6. Center the Roof
- 7. Rotate the Roof
- 8. Reset the Viewing Angle
- 9. Select Your Measuring Tools
- 10. Move the Box out of the Viewing Field
- 11. Pick Your First Roof Corner
- 12. Move to the Next Corner
- 13. Move to the Third Corner
- 14. Finish Clicking on All the Roof Corners
- 15. Did You Click on the Wrong Spot?
- 16. A Couple of Notes on Adjusting Your Lines
- 17. Find the Area of the Roof
- 18. Done!
Click on the images to enlarge them.
Keep in mind that this measuring technique is only usefully accurate for low-slope or “flat” roofs, and satellite images will not help you find the pitch of a roof.
To find the area of a pitched roof, see How to Find the Area of a Sloped Roof.
And even “flat roofs” usually have a little bit of a slope, so you might want to use a roof pitch multiplier once you have your area figured out.
1. Download and Install Google Earth
The first thing you need to do is download and install Google Earth Pro.
Google Earth Pro used to be the paid version of Google Earth (it used to cost $400 a year about ten years ago), but it’s free now.
It includes tools that weren’t available on basic Google Earth, the most relevant tool being a measuring tool that allows you to measure the area of a polygon.
You can download it at: https://www.google.com/earth/versions/
2. Open Google Earth
Once you’ve installed Google Earth Pro, open it. You’ll see an image of the Earth along with various menus and tools around the edge of the screen:
3. Uncheck “3D Buildings” Box
Make sure the box for “3D Buildings” is NOT checked. 3D Buildings mode can interfere with your measurements.
The 3D Buildings option is located under the “Layers” menu on the bottom of the right side of your screen:
4. Search for the Address of the Building
At the top left of the screen, you’ll see a search field. Enter the address of the building you want to measure in the search field and click on “Search”:
This will put a pin on the location and the image field will zoom to the location and center itself on the pin so that you can see your roof:
5. Zoom in on the Roof
The “eye altitude” (shown at the bottom right) at this point is still at quite a distance. For the most accurate measurement, it helps to zoom in so that the roof fills as much of the image field as possible. There are two ways to zoom in: you can use the slider in the top right corner of the image field, or you can scroll with your mouse wheel. (Make sure the cursor is within the image field to scroll.)
6. Center the Roof
To make sure the image field stays centered on your roof, put the cursor (looks like a little hand) on your roof and hold down your left mouse button. This lets you drag the roof to the center of the image field:
7. Rotate the Roof
To make sure the roof fills up as much of the image field as possible, you can rotate the roof using the rotate tool in the top right corner of the image field.
Put the cursor on the “N”, hold down the left mouse button, and move the “N” around the little circle to rotate the image.
It usually works out best if you line up the longest edge of the roof so that it’s parallel with the top edge of the image field.
8. Reset the Viewing Angle
Keep rotating, zooming, and centering the image until you’re satisfied.
At this point, the image will most likely be tilted so that it looks like you’re viewing the roof at an angle, which can be irritating. This can be fixed with the “Reset” tool.
At the top left, click on “View”. This opens a drop-down menu. At the bottom of this drop-down menu, click on “Reset”.
This will open up another little menu. Click on “Tilt”, and your view of the roof will once again be from straight above.
Do not click on “Compass” or “Tilt and Compass”, or you’ll undo all the rotating you just did.
9. Select Your Measuring Tools
Now you’re almost ready to start measuring.
At the top left, click on “Tools”. In the drop-down menu, check the box next to “Ruler”. This opens a box with a little menu across the top. Click on “Polygon”.
The default unit of measurement should be “feet” and “square feet”. If it isn’t, or if it is but you want a different unit, you can change it by clicking on the little unit fields there.
(You probably shouldn’t use “Smoots” as your unit of measurement; few people have ever achieved such a high level of measurement expertise.)
10. Move the Box out of the Viewing Field
Put your cursor in the top area of the little box, hold down the left mouse button, and drag it out of the image field. Do not close the ruler box.
11. Pick Your First Roof Corner
Your cursor is now a little square. Center the square on a corner of the roof and left click your mouse.
This puts a little dot on that corner of the roof.
12. Move to the Next Corner
Move to the next corner of the roof and left click.
A line should appear, connecting the two corners. (In the little measuring tools box, the distance of the line should appear.)
13. Move to the Third Corner
Click on the next corner of the roof. Now you should see a triangle formed by the three corners.
14. Finish Clicking on All the Roof Corners
Continue clicking on the corners of the roof until the lines cover the entire roof perimeter.
YOU MUST GO AROUND THE ROOF IN ORDER, or your line will get messed up and you’ll have to start over.
15. Did You Click on the Wrong Spot?
If you click on a corner but the anchor point is not exactly where you want it, you can fix this.
Put the cursor over the problem dot (anchor point, angle), and the cursor will turn back into a hand.
Hold down the left mouse button, and you can drag the dot anywhere you want.
Drag it to where you want it. The lines will adjust themselves.)
16. A Couple of Notes on Adjusting Your Lines
If you right click on a dot, it will disappear, and the lines will adjust themselves accordingly, removing that angle.
You can add a dot anywhere you want, and the lines will adjust to it, adding a new angle.
17. Find the Area of the Roof
Now that you’ve gone around the entire perimeter of the roof, look at the ruler box, and you’ll see the area of the roof.