How To Measure A Roof

How to measure a roof might not be at the top of the list of things to learn for everyone. But the roof is an essential feature of every structure.

If you are a DIYer or are about to have some work on your roof, you need to know how to take roof measurements. It is the only way to determine how much material it will take to complete the job. Measuring a structure’s roof also helps to estimate how much the materials will cost.

If you are here, you must be interested in learning these details about measuring a roof.

We’ve got you covered with the tools and how-tos of the right way to take roof measurements.

Table of Contents

Tools You May Need To Calculate The Area Of A Roof

Ladder
Long level
Measuring tape
Paper
Pencil or other marking tool

There are different ways to take roof measurements. Depending on the method you use, you may not need one or two of these. We will get into these methods in a bit.

Whether you use one method or another, you must know the pitch or slope of your roof.

So before you begin finding the area of your roof, calculate the steepness of the slope.

How To Measure Pitch

Pitch refers to how low or high the slope of a roof is. To find the roof pitch, measure the vertical rise and the horizontal run of your roof.

There are two ways to measure roof pitch.

From The Roof Top

To do this, you will need a ladder to get to the top of your roof. You will also need a measuring tape.

Mark the twelve-inch point on your level.
Hold the level in a horizontal direction.
Place the end that starts at 0 against your roof so that the other end faces the edge. Ensure that you hold it steady.
Look at the little bubble inside the level. Is it straight? It must be to get an accurate measurement.
This measurement gives you the horizontal component of the pitch of the roof.
Now you need your measuring tape for the vertical component.
Hold your tape measure in a vertical direction.
Place the end that starts at 0 on your roof.
Press the tape measure against the level at the 12 inch mark.
The measurement on your tape is the vertical component of the pitch of the roof.

Using the Rafters

For persons with roofs that have steep slopes, climbing up may be too dangerous or impossible. You need access to the rafters in your attic.

Find the place where your horizontal beam connects with the angled rafter.
Place one end of your measuring tool against the horizontal beam, where the two meet.
Measure 12 inches in a horizontal direction. Mark that point off.
Hold your measuring tape in a vertical direction.
Place it on the edge of the horizontal beam at the point you marked off.
Where your measuring tool joins between the two beams gives the vertical component.

For both methods, if your vertical measurement is 4, your roof pitch is 4:12.

Free Online Measuring Tool To Measure Roof Pitch

These tools are available. Some of them may not be accurate. If you decide to use this method, get one recommended by a reputable roofing company.

Wrong estimates cause costly mistakes.

Now, we get into using the pitch to measure or estimate the size of a roof.

How To Measure The Square Footage Of A Roof

There are different ways to measure the area of a roof. Some of these methods give you an estimate and not an exact number. If you are wondering how do I estimate my roof size, this is what you need to do.

Measure From The Ground

- First, measure the exterior walls of your structure.

Measure from one end of the roof to the next for each wall. Include measurements for the length and the width. Be sure to record these numbers so you will not forget them.

- If you have overhangs, measure to the end of the roof.

There is no need to worry about exact numbers. Your best estimate should be enough.

There is still one more step that you need to take.

The roof dimensions help you determine what number of materials you need to buy. But you cannot look at those numbers and make an estimate. What do you do? There are two options.

1. Draw a top view diagram of your roof and put in the roof dimensions you measured.
2. Forward your drawing to a roofing company.

They should be able to provide you with the information you need.

A DIYer may want to continue with the do-it-yourself method. So, if that’s you and you wonder, can’t I measure my roof online? The answer is yes. You can.

There are free online measuring tools available for use. Input your pitch measurement and roof dimensions to get material estimates. Hit the calculate button.

Estimated ground measurements are not precise. But, they are close to accurate. Whether your roof is simple, flat, has an irregular shape, or a steep slope, this method works.