How To Measure A Roof
In this blog, we will discuss how to measure a roof without leaving your home or office by utilizing Google Earth. Google Earth provides a convenient and cost-effective way of obtaining satellite measurements without leaving the comfort of your home or office. In this blog post, we will guide you on how to get measurements with Google Earth. This method can also be adapted to measure driveways, fences, decks, patios, porches, or anything else that you may need.
Step 1: Open Google Earth
I suggest avoiding Google Earth on your mobile device. It does work on a mobile phone, but I would suggesting using a desktop or laptop computer. In my personal opinion, it just seems to be more accurate. Depending on the size of the roof, I have also noticed that slight adjustments can sway the square footage quite a bit in either direction.
Step 2: Turn off the 3D Buildings layer
Once you have Google Earth loaded up, to get accurate roof measurements, you need to turn off the 3D Buildings layer. To do this, click on the Layers icon on the left-hand side of the screen, and then click on the 3D Buildings option. This will toggle 3D buildings in the selected area. If the location that you are measuring happens to be obstructed with trees, you may want to turn on the 3D Buildings Layer. This can sometimes help with seeing under and around trees.
Step 3: Search for the location
To search for the location of the area that needs to be measured, click on the Search icon in the left-hand side of the screen. Type the address or location in the search box at the top of the screen and press enter. It should portal you to the location, however, it goes into 3D mode and spins around the targeted location.
Step 4: Turn on 2D Mode and Orientate the Camera
To do this, click on the 2D icon on the bottom right-hand side of the screen, and then click on the 2D option. If the button shows 3D, then you are already in 2D mode. Then, click on the Compass icon to align yourself North. Alternatively, you can HOLD Left CTRL + Left Mouse Click and rotate your mouse to orientate the camera in any direction that you want for measuring.
Step 5: Select and Use the Ruler Tool
You should now be looking at the top of the roof. To measure the area, click on the Ruler icon in the toolbar. Left-click on one corner of the roof, a “polygon” will appear, then left-click the next corner, and repeat this process for each side of the roof. Once you come to the last side, drag your cursor over your initial polygon and you should see “close shape”. Left click the initial polygon to complete the process and then you should have the results in the top right-hand corner. Note that you can change the measuring units by clicking the drop-down-arrow that is to the right of the resulting measurement. Make sure feet and square feet are selected.
Alternatively, you can click the last polygon that was created and it will give you the “Distance” in the results. This is helpful for obtaining “linear feet” to quote a gutter cleaning or fence staining jobs.
Step 6: Figure Out the Pitch
You now have the square footage. Now you need the pitch of the roof. In a perfect world, the owner would know the pitch of their roof. This isn’t a perfect world. So, this leaves us few options. Totally guess, not a good option but can be justified. Picking 5/12 or 6/12, the most common pitches, and applying one across the board can be argued, but I don’t think I will get into that. The better option if it is available, in my opinion, is to utilize Goggle Street View.
Grab the Google Man icon in the bottom Right-hand corner and drag him onto the street in front of the house. Now, take a look at the roof and compare it to the chart below.
The chart above represents roof pitches. A flat roof is 0/12. A 3/12 pitch means that the roof rises 3″ every 12″ of span. Keep in mind that 9/12 through 12/12 are considered unwalkable.
Step 7: Multiply Your Square Footage By the Roof Pitch Factor
Utilize the table below to find the roof pitch factor of the measured roof.
| Roof Pitch | Angle | Roof Pitch Factor |
|---|---|---|
| 1/12 | 4.76° | 1.0035 |
| 2/12 | 9.46° | 1.0138 |
| 3/12 | 14.04° | 1.0308 |
| 4/12 | 18.43° | 1.0541 |
| 5/12 | 22.62° | 1.0833 |
| 6/12 | 26.57° | 1.1180 |
| 7/12 | 30.26° | 1.1577 |
| 8/12 | 33.69° | 1.2019 |
| 9/12 | 36.37° | 1.2500 |
| 10/12 | 39.81° | 1.3017 |
| 11/12 | 42.51° | 1.3566 |
| 12/12 | 45.00° | 1.4142 |
In the above example, I ended up with 2017 square feet. Let’s say the roof is 6/12. I would take 2017 and multiple it by 1.1180 (the roof pitch factor)
2017 x 1.1180 = 2,255.006
The example roof is 2,255 square feet.
Bonus Material For The New Guy: How to Quote a Roof Cleaning
Armed with the above knowledge, you can now explain to a potential customer that their 1,000 square foot home has a 2,200 square foot roof.
You have the square footage of the roof, now you need to put a price per square foot. $0.20 – $0.40 is our average price range in central Florida. A lot of things have to be right for us to touch $0.20. Some of those things are, gutters being present and functional , minimal landscaping, low pitch, single-story, asphalt shingle, close location, among other factors. Depending on the complexity, we may charge more than $0.40 per sq. ft.!
Let’s say the above example was a single story-asphalt shingle-that did not have any gutters-with some landscaping-that isn’t too far-type job. We would go $0.25-$0.30 per sq. ft. or between $563.75 and $676.50.
2,255 sq. ft. x $0.25 = $563.75
2,255 sq. ft. x $0.30 = $676.50
Let’s say the above example was a two-story-tile roof-that did not have any gutters-with some lots of landscaping-that is far-type job. We would go $0.30-$0.35 per sq. ft. or between $676.50 and $789.25.
2,255 sq. ft. x $0.30 = $676.50
2,255 sq. ft. x $0.35 = $789.25
We tend to reserve $0.40+ per sq. ft. for 3+ story homes that are complex.
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