Measuring the true surface area of something sloped, like a roof or an embankment.
A shape drawn on a plan measures its flat area. A sloped surface is larger than its plan footprint, and Pitch is what recovers the difference: give a drawing a pitch and its area is multiplied up to the real surface.
Pitch is expressed the way a roof is, as rise in 12. A pitch of 0 is flat, 4 is 4-in-12.
Pitch is a property of the drawing, not the item and not the layer. Open the drawing's properties to set it, or show the Pitch column in the panel and set it there.
It is per drawing because one roof has several planes at different pitches and one layer holds all of them. An item-level or layer-level pitch would be too coarse to describe either.
The area is multiplied by the slope factor for that pitch:
| Pitch | Multiplier |
|---|---|
| 0 (flat) | 1.000 |
| 4 in 12 | 1.054 |
| 6 in 12 | 1.118 |
| 8 in 12 | 1.202 |
| 12 in 12 | 1.414 |
One multiplier is exact for a flat plane whatever its shape or which way it faces, which is why a single number per drawing is enough and no direction has to be given.