Calculating the roofing materials needed for your home or business requires an understanding of the geometry and the ability to complete some basic math problems. For basic roof designs, this is a fairly easy task to accomplish. For roofing designs that are more complex, it is a bit more challenging and requires you to complete several calculations to make your determination. These calculations will give you the total surface area of the roof in square feet.
Things You'll Need
- Tape measure or measuring wheel
On a note pad, sketch out the various geometric shapes that comprise the overall shape of your various roof surfaces. For simple roofs such as a ranch style home, you will likely have two rectangles with which to deal. For more complex roofs, you will likely have several different geometric shapes including squares, rectangles, and triangles.
If you can safely get onto your roof with your pencil, pad, and a measuring device, you begin measuring the outside dimensions of each geometric shape that you have sketched onto your pad. Be sure to write down the dimensions for each side of your shape as you measure them. You will use those measurements to calculate the square footage for each shape. Once you've made those calculations, you'll add them together to determine the total surface area of your roof. See the references below for the formulas to accomplish this task.
If you are unable to safely get onto the roof to do the hands-on measurements, there is another way to determine the square footage of your roof with reasonable accuracy. You can calculate your roof pitch in several ways, the easiest is to go into the attic. After measuring the outside dimensions of your home, enter the attic. Holding a level parallel to the floor so that the 12-inch mark is against the rafter; make sure the bubble indicates level condition. Using your tape measure, find the distance from the front edge of your level up to the roof rafter to determine the rise. The Service Magic Roof Calculator at servicemagic.com shows a diagram and performs the calculations based upon your measurements.
Once you have determined the overall square footage of your roofing system, a simple division problem determines how many "squares" makes up your roof. A square in roofing terminology is 100 square feet (a 10-foot by 10-foot section). You will typically order your roofing shingles in "squares." Divide your overall square footage calculation by 100 to determine how many squares of materials you'll need to complete the roof.
Tips & Warnings
- Don't forget to consider the other materials necessary to install the roof. These items include roofing nails, felt paper, flashing, and if conditions dictate, ice and water shield. Recommendations from roofing experts indicate that you should order between five and 15 percent of extra materials to allow for waste, trimming and mistakes.
- Be extremely careful when you attempt to get up on your roof and move about on it. Wear work boots with skid resistant soles and work gloves in case you slip and need to grab hold of something.
How to Calculate Area for Shingles
You calculate area for shingles by measuring a roof's square footage. However, to buy shingles you also need to determine the number...
How to Calculate Shingles Needed
If you're going to replace the shingles on your home's roof, you'll want to know how many shingles you'll need.
How to Calculate Building Materials
When figuring a job for construction, a few formulas will help you complete a successful project. With a little practice, you will...
How to Use a Roofing Estimate Calculator
Looking ahead at necessary home repairs often means using a roofing estimate calculator. These gadgets can be found free online (see Resources...
How to Estimate Roof Sheeting Material
A roof frame consists primarily of two components: the rafters, which are the load-bearing elements of the roof, and the roof sheathing...
How to Install Ice Shield
In cold climates that experience regular snowfall and icy conditions, a felt roof liner may not be enough to protect a roof...
How to Calculate Materials Needed for a Shed
List of materials needed to build a simple, affordable shed. Options and methods of calculations included.
How to Estimate Material for a Roofing Job
Spare yourself expense and headaches by getting an accurate estimate of roofing materials before you begin your project. This prevents over-purchasing expensive...
What Materials Are Needed to Do a Roof?
Roofs are made of various types of materials: metal, tin, tile and other man-made materials, which can be expensive. They serve an...