Roof Framing

Run, Roof Slope, Gable Height and Gable Area

roof framing run gable height area

Run

Run can be calculated as:

R = S / 2   (1)

where 

R = run (ft, m)

S = span (ft, m)

Example - Run

The run of a roof with 60 feet span is

R = (60 feet) / 2

  = 30 feet

Gable Height 

Gable height can be calculated as

GH = R VR    (2)

where 

GH = gable height (ft, m)

R = run (ft, m)

VR = vertical rise (in/ft, cm/m)

Example - Gable Height

The Gable Height of a roof with 30 feet run and vertical rice 6 inches per foot, can be calculated as

GH = (30 feet) (6 inches/foot)

     = 180 inches

     = 15 feet

Gable Area

Gable Area can be calculated as

GA = GH R       (3)

where 

GA = gable area (sq.ft, m2)

GH = gable height (ft, m)

R = run (ft, m)

Roof Slope

Roof slope is the ratio between the vertical rise and the horizontal run:

RS = y / x   (4)

where 

RS = roof slope

y = vertical rise (in, m)

x = horizontal run (in, m)

In the United States, slope is typically given in inches per 1 foot or as a ratio of inches per 12 inches and is often referred to with units of "pitch". Ex. 

4 in 12 

or 

4 pitches, 4:12 pitch

In metric countries it is common to use degrees or 10 or 100 as denominator. Ex. 

21.8%

or

4:10

Related Topics

  • Miscellaneous - Miscellaneous engineering related topics like Beaufort Wind Scale, CE-marking, drawing standards and more

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