To measure a roof, find both the area of the house and the pitch of the roof. Calculate the number of roofing tiles necessary to complete the job by multiplying the area of the house by the numbers that correspond with the pitch of the roof.
- Find total roofing squares
Use a steel tape measure to find ground measurements of house. Multiply the length by the width to find the total area. If the house has irregular dimensions, measure and calculate each section separately, then add the totals together. Divide the total square footage by 100 to find the number of roofing squares for the roof.
- Find the pitch of roof
Bring a level and tape measure up to the roof. Hold the level horizontally so that one end touches the roof about a foot from the base. At the 12-inch mark on the level, measure the distance between the level and the roof. Anything less than six inches is a low-pitched roof. Six to nine inches is a medium-pitched roof, and more than nine inches is a high-pitched roof.
- Calculate the roof area
For a low-pitched roof, multiply the number of roofing tiles by 1.06 to 1.08. For a medium-pitched roof, multiply by 1.12 to 1.25. For a high-pitched roof, multiply by 1.3 to 1.42.