Roof surfaces are measured in “squares”. A roofing square is equal to 100 square feet of the roof. To determine the number of squares on the gable roof example in this post, divide its total of 20,000 square feet by 100 (20,000 ÷ 100 = 200). This means you would need 200 squares of shingles to cover that roof.
So you need a new roof, whether it’s to adorn your newly built home or to replace your existing roof. Like most North Americans, you’ve wisely decided to go with asphalt shingles due, in large part, to their vast range of styles and color blends. Like most of your neighbors, you plan to have the shingles installed by a professional roof contractor who will handle all the material calculations; however, the information below will help you understand how to estimate the amount of shingles and accessory materials you need for your roof.
Calculating how many shingles you need for your roof is very similar to calculating how much carpet you need for your floors or how much wallpaper you need for your walls; simply determine the area of the roof and divide by the area covered by each package of shingles.
Metal roofing is sold by the sheet/panel. To determine the number of sheet/panels you will need to cover your roof, you should divide the width of the roof by the sheet/panel coverage width.
Most other types of roofing are sold by the square foot. If you need assistance in determining how much roofing you will need, Please feel free to call Sky Roof Measure at – (315) 926-1777
Calculating the Area of a Complex Roof
Areas of complex roofs with many hips and valleys take the most time to calculate. To get started, make a rough sketch of the roof. To simplify things, break down the sketch into rectangles and right triangles and then take as many measurements of the roof as you can to match the sides of the rectangles and triangles on the sketch.
Square lines off eaves edges or ridges can be determined by using visual cues from the existing roof. These will help you measure the lengths of the sides of the rectangles and triangles. For example, the cutout slots on shingled roofs run perpendicular to the eaves, and nail rows in sheathing are very close to square as well. While it can be challenging sometimes to get accurate measurements, don’t be too concerned and round lengths to the nearest 6 in.
When your sketch is filled in with measurements, determine the size of the roof area. The area of a rectangle is length multiplied by width, while the area of a right triangle is the length of the two sides that meet at the 90-degree corner multiplied together and divided by two.
That said, on average, most contractors will charge between $3.50 and $5.50 per square foot or $350 to $550 per square (100 sq. ft.) to install or replace an asphalt shingle roof on a typical house. Thus, at the mid point of the above price range, you can expect to pay about $4.50 per sq.