If you’re determined to tackle a roofing job yourself, it will be important to calculate the exact square footage of your roof in order to know how much material you’ll need. After taking a few simple measurements, you can figure out the area of your roof by sketching a rough diagram and breaking the roof up into smaller sections, which you can then add together to get your square footage grand total. If getting onto your roof isn’t an option, you can also estimate its size from the ground by measuring the area of the exterior walls and multiplying that number by the roof’s slope.
Most roofing contractors typically measure a roof by calculating the area of a roof and then adding on 10% for possible waste. When roofing contractors are in high demand such as they are in Florida after a hurricane, this way of estimating a roof may be okay, but in a tighter market you may need to have sharper estimating skills in order to compete with your competitors and make a profit. Here I’ll show you how to get a quick, and highly accurate roof estimate on all types of roofs.
Before submitting a bid for any roofing job, you need to know what the materials will cost. In order to know how much materials you’ll need you must know the size of the roof. First you will need to measure the total area of the roof. Then you will need to measure the lengths of the ridges, rakes (gables), hips, valleys, & eaves. If the job is a new construction roof installation you may be able to get the measurements from the blueprints; however, if the roof is a roof replacement or roof repair then you will need to measure the roof yourself.
Slope
- You’ll also need to measure the slope, or angle, of your roof.
- To do this, position your ladder near the top point of your roof.
- With your measuring tape, measure vertically from the top point to the bottom point of your roof. (This is also called the rise.)
- Repeat this over 12 inches, then place the measurement over “12”. (For example: If your rise is 4 inches over 12 inches, then your slope measurement is 4/12.)
How to measure your roof area from the ground
A more accurate way to calculate the area of the roof than using Google Earth is to get outside to estimate the roof pitch and the base area of the property. Using these two figures, we can get a good idea of the shingle roof’s square footage and estimate your asphalt shingles’ needs and costs. This DIY technique can be helpful, especially if you are not comfortable getting on your roof, or if you have limited access to it.
Ground measures only work well for a gabled roof, since there are usually just two main rectangular pitches to calculate area for. For more complex roof shapes, like hip roofs, you’ll need to work with a roofer or measure from on top of the roof itself to calculate its total area.
You’re a few simple steps away from your aerial roof measurements (and a better back!):
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- Enter Your Details: Give us your name, email, and phone number so we can contact you.
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- Enter Your Address: Let us know which roof to measure.
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- Leave Notes: Tell us to exclude the garage or anything else we should know before sending your measurements.
- Confirm Your Address: Hey, we just want to know we’re measuring the right house!
That’s it! Just proceed to the payment page (if necessary), and you’ll get your measurements instantly. See, wasn’t that way better than spending all day on the roof in the hot sun?
From there, you’ll create your free toolbox account where you’ll have access to your measurements and a ton of tools to make your roof project easier, cheaper, and faster.
The roof slope is defined by the rise (in inches) per 12 inches of run of the roof. For example, a “4 in 12 roof” is a roof that rises 4 inches for every 12 inches of horizontal run.
