When measuring the pitch of a roof, what is most commonly assessed?

The pitch of a roof is primarily a measurement of its slope, which is expressed as a ratio of the vertical rise to the horizontal run. This measurement helps in determining how steep the roof is, which can impact water drainage, snow load, and overall aesthetic design. Assessing the slope is critical for ensuring proper installation of roofing materials, as different pitches may require specific types of roofing to ensure effectiveness against weather and water intrusion.

In contrast, while the length of rafters, width of eaves, and height of the ridge are relevant dimensions to consider when analyzing a roof's overall structure, they do not directly inform the pitch of a roof. Instead, these measurements can affect other aspects of roof performance but do not define how steep or shallow the roof is, which is the essence of pitch. Therefore, the assessment of the slope is the most relevant and common measurement when discussing the pitch of a roof.