Rafter pitch, often referred to as roof pitch, is a fundamental concept in construction and refers to the angle of a roof.
Understanding Rafter Pitch
Based on construction principles, rafter pitch is fundamentally defined by the angle created by the roof structure.
Specifically, it is:
- the angle that is created as the rafter leaves the ceiling joist.
This angle dictates the slope of the roof and has significant implications for design, material choice, and drainage.
How Rafter Pitch is Represented
Beyond just an angle measurement (like degrees), rafter pitch can also be described using a ratio:
- It can also be represented as the proportion between the rise and the run of the roof.
Rise refers to the vertical distance the roof rises, while run refers to the horizontal distance it covers (typically measured from the outer wall to the center of the ridge). This proportion is often expressed as rise over run (e.g., 6/12, meaning the roof rises 6 inches for every 12 inches of horizontal run).
Rise and Run Example
As an example, consider a roof pitch:
- for every 1 metre in width, the roof rises 1 metre in height – or otherwise known as 45 degrees.
This illustrates how an equal rise and run correspond to a 45-degree angle.
Understanding rafter pitch, whether expressed as an angle or a rise/run ratio, is crucial for planning and building a functional and structurally sound roof.
