The Better Business Bureau received 3.3 million inquiries for trustworthy roofers in 2011. Roofing, in fact, was one of the industries that drew the most BBB inquiries. During times of natural disasters, unscrupulous contractors roam about looking for homeowners to swindle, and some will even damage your roof to convince you that you need their services. Do some of your own calculations first, so you can have an educated conversation with a contractor about what she'll do to replace your damaged roof.
Measure the Ground Dimensions
The ground dimension of your house is the starting point for how much roofing you need. If your house is rectangle, measure the length and width of your house, and multiply these two numbers to arrive at your home's square footage. If your house is irregularly shaped, measure it in sections to determine the square footage of each section, then add all of these measurements together. Divide the total square footage by 100 to calculate the number of roofing squares that make up your home's area. Each roofing square is 100 square feet.
Calculate the Roof Pitch
The roof pitch is how much slope the roof has to allow for runoff of water or snow and ice -- or for living space clearance. Roof pitches may be low, medium or steep. A low-pitch roof has less than 6 inches of rise in the roof per foot of length, medium-pitched roofs have between 6 and 9 inches of rise and steep-pitched roofs have more than 9 inches of rise. Mark a section on a carpenter's level one foot from the end. From a ladder, place the end of the level at the edge of the roof. While holding the level with the bubble centered between the two lines, measure from that one-foot mark vertically to the roof. This measurement is the amount of inches of rise per foot.
Determine the Roof Squares
Multiply the ground-measurement roof squares by the correct multiplier based on the pitch of the roof. If your roof has a low pitch, multiply the number of ground measurement squares by 1.06 to 1.08 to determine the total squares of roofing surface present. For a medium-pitch roof, multiply by 1.12 to 1.25. For a high-pitch roof, multiply the number of squares by 1.3 to 1.42.
Price the Materials
Roofing materials, such as asphalt shingles or steel roofing, are priced by the square. Multiply the amount per square for your desired material by the total amount of roof squares. Also include the cost of any underlayment for the roof, as well as fasteners, such as roofing nails. Compare the aesthetics of the various materials, as well as the durability based on the weight and the warranty, to be sure you are getting the best value for your dollar.
Price the Installation
Home centers and building contractors often quote the price of installation of roofing per square. This pricing is an estimate and does not account for any extra labor required to repair damage to the roof deck -- damage that made the reroofing necessary -- or to trim roofs with extra peaks and valleys, which require additional labor.
Getting an Estimate
If you are having your roofing installed, consult with different qualified contractors to obtain estimates for the installation of your roof. The contractor will be able to quote the price for special trim work and to repair roof decks damaged by water or other forces. Before hiring a contractor, check to be sure he is licensed and carries liability and worker's compensation insurance, or you could be expected to pay for any of his employees' injuries. Check with people he has recently completed work for, and make sure those jobs were completed correctly and on time.