How to measure the ceiling: five basic steps
If you’re looking for information on “how to measure your ceiling”, you’ve come to the right place. This article will walk you through the five basic steps.
How to measure the ceiling: Step n. Tip #1: Make Your Drawing
A good place to start is by making a bird’s-eye sketch of your roof. Visualize the ceiling as if you were a hundred feet above it looking down. What would you see? Draw the outline of the entire roof. Then show each eave, rake, valley, hip, and ridge. Show all the details, including pipes, vents, chimneys, skylights, and solar panels. All of these things affect your estimate of roofing costs. Try to keep your drawing somewhat proportional, but it doesn’t have to be drawn to perfect scale.
How to Measure the Roof: Step #2: Measure the Slope
I like to measure the slope first, because it’s important and easy to forget. This method requires a carpenter’s level (any length will do) and a tape measure. Place one end of your level on the roof with the other end pointing straight “down the slope.” Raise the end downhill until the bubble is centered. Then, keeping the tape measure upright, measure the height, which is the distance from the bottom of the level to the ceiling.
If your level is a foot long, you’re all set. What you see is what you get. If your level is two feet long, divide the elevation by two. If your level is three feet long, divide the elevation by three.
On roofs with high profile roof components such as shingles or wood shakes, you may need to run a board in multiple courses to get a true reading.
Sometimes it is easier to measure the fascia board slope or drip edge rather than the roof surface. As long as it’s parallel to the ceiling, it doesn’t matter what you measure.
Record the slope directly on your drawing.
How to Measure the Roof: Step #3 – Take Measurements
Then, record the measurement of each vertical, horizontal, and diagonal line on your drawing. All will be needed to calculate the correct amount of roofing material you will need. Also be sure to measure each section of the roof from the eave, directly up the roof to the peak.
The easiest tool to measure most roofs is a measuring wheel. It’s fast and doesn’t require anyone else to hold the other end of the tape. But it is a mechanical device and you need to make sure it works properly.
The most accurate tool for measuring is a tape. It’s also useful for some roofs, like barrel tile roofs, where a wheel doesn’t roll very well. I use a 25 and 100 footer.
It’s much easier if you round each measurement up to the next larger foot. I’ve also found that if roofers are careful, that’s about the right amount to allow for waste on most roofs. If you have piece rate roofers, rounding also virtually eliminates all roof size disputes.
How to measure the roof: Step #4 – Calculate the area
When you have all the measurements you need, take a calculator and calculate the square footage of each section of the roof.
No matter how complicated the roof is, you can divide it into a series of rectangles and triangles. From there, it’s just simple math. For rectangular sections, multiply the length by the width. For triangular sections, multiply the length by the width, divided by two.
It’s a good idea to number each section so you don’t forget any. Then just add up all the sections to get the total square footage. Dividing the total by 100 gives you the number of “squares” of roofing material to order.
To calculate how many shingles you will need for your starter course, simply add the linear feet at the eave and divide by the length of one shingle. However, do not cut all your starters at the beginning of the job. As you shingle each section, you may be able to use what you cut from the top course for the footings of the next section.
For your hips and ridges, you can choose from pre-cut shingle packs or cut your own from three-tab shingles. Either way is fine, but not everyone has the same coverage. The pre-cut type will have the coverage printed on the package. One package of standard three-tab shingles will cover approximately 33 linear feet of hip or ridge.
How to Measure the Roof: Step #5 – Order Your Materials
Please note that some shingles are packaged in three packages per square, while others are packaged in four (or more) packages per square.
You will rarely calculate the EXACT amount of roof you need for the job. Having a little to spare is often preferable to not having enough to get the job done. But try to keep some packages out of the weather in case you need to return them. Vendors may charge you a restocking fee, but they don’t mind returning them as long as the packages are in good condition and you still have your receipt.