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A Roofing Calculator: Why You Need One and How to Use It

If your roof had an issue, there once was a time when very few of us thought twice about hiring a pro to fix it. And with that, there wasn’t much need for a roofing calculator. But since the COVID-19 outbreak and its various unforeseen stallings on home projects (shrunken income, lower budgets, public health concerns), many homeowners have considered the option to save on labor costs by way of the do-it-yourself alternative for re-roofing their homes.

That said, roofs are a costly investment. While it’s typically recommended that a licensed professional do the job, with the right preparations it is possible to re-roof your own home. [Warning: Attempting to re-roof a home yourself has many risks in addition to the complications that arise from doing things incorrectly. We highly recommend getting a quote from Ace Construction Roofing Company. You can discuss with them the pros and cons of trying to do this yourself, and your best options for hiring Ace.]

Either route you choose to go, consider using the measurement tool that’s a re-roofing project must: a roofing calculator. This will show you the total surface area of your roof measured in square footage, which will inform you how many shingles and nails you’ll need to purchase, and later, more importantly, how much it’s all going to cost.

When measuring your roof, note that a “square” in roofing terms equals 100 square feet. (For example, 12 squares equal 1200 square feet.) When ordering shingles, you’ll order them by the square.

DIY-ing? Roofing Calculators and other Factors to Keep in Mind

Do your homework. You will need to weigh factors like time you can invest, the realistic project timeline, and your budget. When it comes to re-roofing, mishaps are costly, and common roofing mistakes should be researched beforehand.

Other factors to keep in mind will be roofing material, number of shingles, and even the number of nails you’ll need. (Do you live in a windy area? You’ll need even more: six nails per shingle, rather than the typical five). And where do you get the materials? Many roofing 

Using a Roofing Calculator to Measure YourRoof’sSquareFootage

To access a roofing calculator, consider tools like RoofCalc or, both of which are free and user friendly. Remember the term “plane” from 9th grade geometry? Here, plane refers to each distinct flat surface of your roof, or “roof plane.” (For instance, a sloping shed may only have one roof plane, whereas a gable has two.)

Remember also that multiplying length by width equals area? Simply measure each plane’s square footage, then add all of them together. This sum equals the total square footage of your roof.

To calculate the square footage, measure the area of each plane. From the top of your roof, throw a rope down and mark to measure where it meets the eaves (the point where your roof either meets or “overhangs” with the house).

Of course, this sounds simple, but when you start getting “planes” that are trapezoids or pentagons, or irregular shapes with unequal sides (Remember regular and irregular polygons from Geometry class? – oh, yea, we hope you didn’t sleep through that class.) figuring the square footage can be complicated. Our suggestion…just put your mind at ease and get a quote from Ace Construction Roofing Company.

Measure The Roof Slope (also using a roofing calculator)

A roof surface may be either ‘functionally flat’ or ‘pitched.’ A roof’s pitch, or slope, measures its steepness, shown as either a ratio or the number of angular degrees a roofing plane “deviates” from horizontal level. You will need to measure this as well, especially if your roof is particularly steep.

The online roof calculators ask you for each measurement needed. The better ones will explain how to get the measurements. Be aware, if you are off on your measurements, this can significantly affect the accuracy of your calculations. And if you are ordering special shingles and come up short it can be a real problem.

Roofing C basics For a Simple Gable Roof

To calculate pitch, first measure the roof length by measuring the exterior walls (plus overhang) for the length of the house parallel to the ridge (the point where the roof starts to slope).

Then, from either ground or rooftop, toss a rope over the ridge and mark it where it meets each eave. This will measure the width. Be sure to do this for each roof section that has a horizontal ridge.

You can also determine your roof pitch by using other types of roofing calculators: a pitch gauge (available at most home improvement stores) or a smartphone app (available free through any app store).

Calculate Your Materials (how many nails you’ll need).

Roofing calculators won’t tell you this, nor the other equipment and supplies you will need. So, you’ll have even more research to do. But for the nails, once you’ve determined your number of shingles, multiply times five, the standard number of nails per shingle. (As mentioned earlier, if you live in a particularly windy region, count six per shingle.)

Having Second Thoughts?

If after reading this your head is beginning to spin with calculations, not to mention many other more serious concerns, then do yourself a favor and call Ace Construction Roofing Company. Ace roofers are experience, trusted and highly rated and are a preferred contractor with Owens Corning roofing materials.