c. Cut of a Roof. The cut of a roof is the rise over the run (such as 4/12 roof) or the pitch of
the roof (see Figure 3-27).
Figure 3-27. Roofing terms
d. Span of a Roof. The span of any roof is the shortest distance between the two opposite
rafters' seats (see Figure 3-27).
e. Line Length. In roof framing, line length is the hypotenuse of a triangle whose base is the
run and whose altitude is the total rise (see Figure 3-27).
f. Horizontal Line. A horizontal line is one level with the building foundation.
g. Overhang. The overhang is that part of a rafter that extends past the outside edge of the
walls of a building. When laying out a rafter, this portion is in addition to the length of a rafter and is
figured separately. The overhang is often referred to as the tailpiece.
h. Total Rise. The total rise is the vertical distance from the wall plate to the top of the ridge.
i. Run. Run always refers to the level distance any rafter covers--normally, one-half the span.
j. Unit of Run (or unit of measurement). The unit of measurement, 1 foot (or 12 inches), is
the same for the roof as for any other part of the building. Using this common unit of measurement,
the framing square is used in laying out large roofs.
k. Pitch. Pitch signifies the amount that a roof slants and the ratio of rise (in
inches) to run (in inches). Using this method, 4, 6, or 8 inches of rise per foot of
EN5156
3-20
Previous Page
