- Take ground measurements with a tape measure. Measure the length and height of the outside house walls. Multiple these two numbers to calculate the square footage. For example, if your house is 50 feet long and 30 feet wide, the square footage is 30 X 50 or 1,500 feet.
- Convert the square footage to roofing squares by dividing by 100. For example, 1,500 divided by 100 is 15 roofing squares. There are 100 square feet in a roofing square, and this is how roofing measurements are taken.
- Calculate roofing pitch, which makes up for the overhang, slope or architectural twists of a roof. For a low slope, use 1.15 to 1.25; for a medium slope, use 1.25 to 1.4; for a high slope use 1.41 to 1.7. A low slope rises 3 feet for every 12 feet of horizontal length; a medium slope rises 6 to 9 feet for every 12 feet of horizontal length; a high slope rises 9 inches for every foot of horizontal length. If you find this difficult to calculate, have a professional assist you. This is the most complicated measurement in roofing.
- Multiply the square footage by the pitch. For example, if your 1,500-square-foot house has a medium slope, you could multiply 1,500 by a middle range number such as 1.35.
- Decide whether you have material preferences. Note what your roof is made of and if the nature of the job calls for reinforcement with stronger materials.
- Note the required start and end date of construction. If you need the job finished by a certain date, you might have to pay more for longer hours of labor on a faster schedule.
- Check the history and reliability of several contractors. Have consultations with your top five picks. Relay information about the size, nature, material preferences and dates of construction. Compare pricing and rule out any outliers that are radically higher or lower than the others. Extremely cheap pricing could compromise the quality of the job. Choose between contractors offering average pricing.
How to Estimate Roofing Repairs
Estimating the cost of roofing repairs is a delicate science, especially since tiny errors can cause monumental costs. To estimate roofing repairs accurately, you will have to take into account several factors at once, then gather estimates from a handful of reliable contractors for comparison. Having all of the necessary information prepared before talking to a contractor could save you hundreds of dollars.