Jack Rafter Function [Jack]   Jack Rafter Function

The Jack Rafter Layout Function provides the following layout information for hip roofs beyond the information provided by the [Hip/V] (Hip / Valley Rafters) Function:
Information required for this function includes:




Also, if an Irregular Pitch is stored in [IrPitch] then more presses of the [Jack] key will yield the following:
In addition to [IrPitch], calculations for Irregular Jack Rafters are based upon if the [Prefs] Irregular Jack Spacing is set to either On-Centers or Mating.  See illustrations, below for more explanation.


Irregular Hip/Valley layout with Rafters mating at the hip/valley.


Irregular Hip/Valley layout with rafters spaced at the on-center distance.

Example of a Regular Hip/Valley and Jack Rafter calculation:  (see [IrJack] for an Irregular Hip/Valley example.)

Part A. Common Rafter Length and cut angles.
Input
[clr] [clr]
12 [Feet] [Run]
7 [Inch] 1 [ / ] 2 [Pitch]
[ Diag ]   
[ Diag ]   
[ Diag ]   
Display
0
Run
    12ft
Pitch
    7- 1/2in
Diagonal
    14ft 1- 13/16in
Plumb
    32.01°
Level
    57.99°



Part B: Hip/Valley rafter length and cut angles.
Input
[ Hip/V ]   
[ Hip/V ]   
[ Hip/V ]   
[ Hip/V ]   
Display
Hip/Valley Rafter Length
    18ft 6- 5/8in
Plumb Cut
    23.84°
Level Cut
    66.16°
Cheek Cut 1
    45.00°


Part C: Jack Rafter Layout.
Input
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   

[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
[ Jack ]   
Display
Jack Rafter On-Center Spacing
    16in
Jack Rafter Length Increment
    1ft 6- 7/8in
Jack Rafter 1 Length
    12ft 6- 15/16in
Jack Rafter 2 Length
    11ft 0- 1/16in
Jack Rafter 3 Length
    9ft 5- 3/16in
Jack Rafter 4 Length
    7ft 10- 5/16in
Jack Rafter 5 Length
    6ft 3- 1/2in
Jack Rafter 6 Length
    4ft 8- 5/8in
Jack Rafter 7 Length
    3ft 1- 3/4in
Jack Rafter 8 Length
    1ft 6- 7/8in
Jack Rafter 9 Length
    0ft
Jack Rafter Plumb Cut
    32.01°
Jack Rafter Level Cut
    57.99°
Jack Rafter Cheek Cut
    45.00°


Found an error?  Have questions or comments?  We really would like to hear from you. Use the mail icon below to send us your discoveries, thoughts or questions.

Email
BuildCalc


BuildCalc.com