Johnson-level-tool-mfg RAS-1 Manual de usuario descargar pdf (Pagina 27)

COMMON RAFTER LENGTH = 15' 7-1/2"

SUBTRACT (W – P) FROM TABLE = 1' 2-3/8"

FIRST HIP JACK RAFTER LENGTH = 14' 5-1/8"

The tail length must now be added to this length. For all

remainingjacks,subtractthefullspacing(W).Example:

ﬁnding in the tables the amount to subtract for a spacing

of24",weget:

FIRST HIP JACK RAFTER LENGTH = 14' 5-1/8"

SUBTRACT (W) FROM TABLE = 2' 4-7/8"

SECOND HIP JACK RAFTER LENGTH = 12' 0 1/4"

Continue with this process until you get to the last jack

rafter(theprocessisidenticalforvalleyrafters).Always

remember to measure the jack rafter length on the long

side of the rafter because of the bevel.

Cripplejacks(seeFigure8)usethesamemethodas

above, but must be beveled at both ends. Therefore, the

subtraction for both ends must be made from a common

rafter length as if it went from the plate to the ridge. The

cripple jack rafters are actually being measured from long

pointtolongpointdiagonallyalongthetopedge.Bymea-

suringdiagonally,youwillcompensatefor1/2ofthehip

thicknessand1/2ofthevalleythickness.

TAIL OR EAVE LENGTH: The tail or eave length for all hip

jack rafters is the same as for common rafters. If desired,

use a common rafter for a pattern. Cripple and valley jacks

havenotail(SeeFigures14and15).

LUMBER LENGTH: The lumber length is found by using the

same procedure outlined for common rafters, but sub-

tractingfortherafters’position(seeabove).

JACK RAFTER LAYOUT

JACK RAFTER LAYOUT CUTS: Seat notches and bottom

plumb cuts for hip jack rafters are the same as for com-

mon rafters.

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Johnson-level-tool-mfg RAS-1 Manual de usuario Pagina 27