Framing & StructuralQuestion 325 of 700
CALCULATION: A building is 28 feet wide with a central ridge. Ignoring ridge-board thickness, what horizontal run does each common rafter span from the exterior wall to the ridge?
a.14 feet
b.28 feet
c.7 feet
d.21 feet
Explanation
For a symmetric gable, each common rafter spans half the building width horizontally: 28 / 2 = 14 feet of run (the small ridge-board thickness is ignored here). 28 feet is the full width, 7 feet is a quarter, and 21 feet is three-quarters of the width.
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