Importance and Measurement of Roof Pitch

Roof pitch is the measurement of the angle of your roof. It is one of the key elements of your roof which is why it is vital to understand its purpose and why it is necessary for the security of the structure.

Roof pitch is one of the most viable features of any roof. It is actually the measurement of the steepness and slope of the roof. Roof pitch is calculated as a ratio of the roof’s vertical height to its horizontal span.

In the US, roof pitch is mostly measured in inches and represented as a ratio. If the first number is higher in ratio it means that the roof will be steeper. The second number measures the horizontal area which is mostly measured in 12 inches or one foot of roof.

Importance of Roof Pitch

Roof pitch acts as a savior when it rains and snows. Residents of areas that experience heavy snowfall and rainfall prefer to build roofs with a steeper pitch. Strongly built roofs thwart pooling of water or gathering of snow because with passage of time this can cause damage to your roofs like mild cracks, leaks, or even full collapse.

Common Types of Roof Pitch

The categories of roof pitch are not as follows:
Flat: These roofs are not flat but they are slightly angled to make the drainage system better.

Low slope: These types of roofs require different practices and materials to prevent leakage. These roofs allow easy walk-in but are less efficient to cover rain and snow.

Medium slope: These roofs allow a good balance between snow and water running with easy access.

Steep slope: These kinds of roofs require extra fastenings and are challenging to walk on. When you build a high-pitched roof it will cost you a little more, because, vertical angle means that the span of the roof will be longer and requires extra material to build.

Further decorations to increase the charm of the roof adds more costs to it. To be precise, in areas where there is light snow, a low-pitched roof will do the job best. Materials required for a low pitch roof include metal or concrete roofing, whereas, white tiles and shingles are best suited for moderate to high pitch roofing.

Climate change plays a key role in selecting the roof pitch for your home. When you live in an area where it snows heavily you will be needing a higher pitch to get your house protected from snow loads.

Besides heavy snowfall, intense seasonal monsoon rains will require you to have enough roof pitch to ensure that the water runs off quickly from your roof.

Collective Roof Pitch Angle adopted by Constructors

Roof builders mostly opt for the four most common roof pitch angles for the construction of roofs. These include:

Flat roof pitch: It is also known as minimum roof pitch because the steep path of the roof is too small. Contradicting its name, the roof pitch is not totally flat there is a small angle allowing water to drain. This kind of roof pitch is most commonly used in backyard sheds with around 1:12 angle size.

Low-slope roof pitch: This kind of roof pitch is mostly adopted for the construction of office buildings or houses where there are a lot of chances of walking movements. This pitch angle is mostly and approximately between 2:12 to 4:12 allowing water or snow to run-off effortlessly and quickly.

Medium-slope roof pitch: This is one of the most adopted pitches used for house construction. The angle of this pitch is around 6:12 to 9:12 allowing water and snow to flow out easily. This roof pitch also facilitates moving and walking effortlessly.

Steep slope roof pitch: This is the steepest pitch and lies above 9:12 angle. It allows water to be drained easily but it is really hard to walk on this type of roof pitch.

How to measure roof pitch?

Roof pitch is calculated from the same formula that works for right triangles. You can use the equations mentioned below to find out the length of the slope and rafters.

  • From the Pythagorean theorem; rafter2 = rise2 + run2
  • When you want to express in percentage; rise/ run = pitch
  • When the angle is expressed in degrees; pitch= tan (angle)

When you want to calculate the roof pitch in the form of x:11 you will only calculate the pitch and add 11 for the length of run.

Measuring Slope:

When you are planning to measure slope you will be needing a carpenter level experience, a measuring tape, and a pencil. Calculate 12 inches from one end of the level and mark a spot. You can also calculate your measurements from the incomplete attic space under the roof. When you measure the slope from the surface of the roof it will not produce accurate results because of the rough surface of the roof covering. Start from the incomplete attic space and locate a roof rafter board that is easily accessible to you. Then start placing the end of the level against the bottom edge of the roof and grip it tightly.

Start measuring from 12 inches and blot the level vertically to the bottom edge of your rafter. 12 inches indicate that the roof will be 12 inches higher. Strongly hold the vertical level against the bottom edge of the rake board.

When you measure the slope of the roof from the surface of the roof you will get inaccurate results because you are not using a flat surface from the slope. In this case a 48-inch carpenter’s level or a good 2×4 board will be worthwhile in creating a smooth surface which will accurately reflect the slope of the roof.