roof blueprint

How to Measure a Roof From the Ground

If you’re planning work on a roof and don’t have the building plans, taking preliminary measurements from the ground allows you to approximate the roof area and estimate some costs. Measuring hip roofs, dormer roofs or roofs on hillside homes from the ground requires experience and special equipment. But, you can measure a gable or flat roof from the ground with the help of an assistant.

Method 1: Counting asphalt shingles to measure your roof area from the ground.

Most asphalt shingles are three feet wide with three tabs. Each tab is got 5 inches of reveal. So by counting these in digital photos you can come up with pretty reliable dimensions. If there is any doubt on the shingle dimensions, you can calibrate the method by measuring a typical shingle in a lower, accessible location.

Method 2. Pythagorean Theorem.

Measure the horizontal run of the roof surface from the ground (‘a’ in the third figure below). Then count the number of shingles to the peak of the roof. Multiple the number of shingles times the width of each shingle (which you can measure at ground level) to get ‘b’ in the figure below. Then calculate the line length of the roof (‘c’ in the figure) using the Pythagorean Theorem; c = square root (a squared + b squared). It is also easy to calculate the roof angle by taking the inverse tangent of b divided by a.

With these simple tricks you can measure your roof area from the ground.  

Roofing Calculator

How Roof Pitch is Calculated

To accurately calculate the area of your roof, you must first determine its slope, or pitch. A roof’s pitch is determined by how much it rises vertically for every foot it runs horizontally. Thus, a moderate “6 in 12” roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs. A “12 in 12” pitch is a steep, 45-degree angle roof. See the image below for more explanation on rise, run and pitch.

Three Easy Ways To Measure Your Roof’s Pitch

Pitch Measurement Method 1

Roof Pitch Calculator

1. On a ladder beside the roof, place the level a foot or so up the roof, hold it level, and measure from the 12-inch mark on the level’s bottom, straight down to the roof. If this distance measures 4 inches, you have a 4 in 12 pitch; 8 inches and you have an 8 in 12 pitch.

Pitch Measurement Method 2

Roof Calc

2. On a ladder at the gable end of your house, place the level against the gable trim, flat against the side of the house. Now measure from the 12-inch mark of the level up to the bottom edge of the gable trim. This distance is the roof’s rise.

Pitch Measurement Method 3

Roofing

3. In the attic, place the level against a rafter with the 12-inch mark on the bottom of the rafter. Measure from the end of the level up to the bottom edge of the rafter. That is the roof’s ris

 

Satellite roof measurements

How to Measure a Roof

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

  1. You’ll also need to measure the slope, or angle, of your roof.
  2. To do this, position your ladder near the top point of your roof.
  3. With your measuring tape, measure vertically from the top point to the bottom point of your roof. (This is also called the rise.)
  4. 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.

Roof Measurements From Satellite

You’re a few simple steps away from your aerial roof measurements (and a better back!):

    • Enter Your Details: Give us your name, email, and phone number so we can contact you.
    • Enter Your Address: Let us know which roof to measure.
    • 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.