Dr-Fix-It! Rafter Definitions

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RAFTER DEFINITIONS

COMMON RAFTER: A rafter that runs 90 ° from top of wall plate to roof ridge, and forms the hypotenuse (or diagonal) of a right triangle.

VALLEY RAFTER: A rafter that runs from top of wall plate to roof ridge at the intersection of gable extension with main roof.

HIP RAFTER: A rafter that runs from top of wall plate to roof ridge diagonally.

HIP JACK RAFTER: A rafter that runs 90 ° from top of wall plate to hip rafter.

VALLEY JACK RAFTER: A rafter that runs from ridge to valley, 90 ° to ridge.

CRIPPLE JACK RAFTER: A rafter that runs from hip to valley, 90 ° to ridge.

DORMER RAFTER: Rafters that set on top of main roof when remodeling or room addition is made without cutting into main roof causing weakening.

RAFTER RUN: Run is that part of the building the rafter will span. Stated another way, it is the level or horizontal distance the rafter will run. (Run is measured in feet.) When measuring building width, it is best to use steel tape so that you can measure full width of building, measuring from outside to outside of wall or plate which rafter will rest. If siding or other material extends up to top plate, measurement is taken from outside of that material. When ridge board is used, deduct half the width of the ridge board from the run length.

RAFTER RISE: Rise is the vertical measurement the high end of the rafter is to be above its lower end or the amount the rafter will rise vertically.   (Rise is usually measured in feet excpet when calculating the Inch Rise Number).