Unless there is an eave hanging so low, you have to climb the ladder and working at a rate of 1 or 2 feet. Place one end of the level in the ceiling and horizontal level.
Then, measure down directly from the end of the level in the air to the ceiling surface.
Measurement in inches is the slope of the roof if you are using a rate of 1 foot. With the rate of 2 feet, divide by 2 to determine the size of the slope (14 inches from the ceiling level to the level equal to the slope of 2 feet 7 inches).
Note: The "Slope" is often used incorrectly as a synonym with reference to the ceiling. The slope is defined as the vertical elevation (in inches) per foot of horizontal dimensions.
The tendency is the ratio (ratio) between elevation and the total length. For example, a ceiling that rises 6 inches for every 12 long called the "sixteen" or roof 06:12, with a slope of ¼.
Calculating the size of the roof
With dimensions of the roof and its slope, you now have to use a multiplier to calculate the size of the roof tilt accurately. Use the "conversion factor" table below to find the appropriate multiplier for several roof slopes.
Simple gable roof as found on the ranch and colonial houses are easy to calculate. Just take the floor dimensions, multiply the length by the width (excluding protrusions) and multiply it by the multiplier ceiling slope.