Replies

1. 
   kennedy136 | Nov 17, 2002 04:49am | #1

   KELLY,

             Whatever your pitch cut  on the commons/jacks is: example 8in 12,  your hip cut will be 8 in 17 assuming that both sides of the hip are the same pitch { some roofs have 2 different pitches such as an 8/12 on one side of the hip and a 6/12 on the other in which case you have an irregular hip which is an entirely different animal}.  If you look at your speed-square you will see that there are 2 different scales, one for hip cuts and one for commons.  The hip scale will not result in as steep an angle because it reflects the longer run (17 inches instead of 12inches)  Hope this helps you out.

                                                                                          Mark

2. 
   01MJ01 | Nov 17, 2002 06:36am | #2

   Kelly, your hip/valley tail cut is 18 degrees. On the miter it is 36 degrees.

   If your cutting facia, it's 29 on the angle and 36 on the bevel(miter).

   Got this out of Mussells' Roof Framers Bible.

   hope this helps you out,

   matt

3. 
   Joe_Fusco | Nov 17, 2002 04:54pm | #3

   KELLYREN,

   Try it with an inexpensive scientific calculator using these formulas. . .

   Fascia miter (Face angle) = tan-1(( sin (roof pitch angle) / tan (angle of joint / 2 )))

   Hip miter (Face angle)= Tan-1((sin (roof angle) * cos (roof angle) * cos (joint angle/2)) * tan (comp-joint-angle))

   Fascia & Hip bevel = sin-1(cos (roof pitch angle) * cos (angle of joint / 2))

   View Image

4. 
   Ragnar17 | Nov 17, 2002 11:49pm | #4

   Kelly:

   Mark is right on: in simple hip framing, use 12" run for your commons, and 17" run for your hip rafter.  (In plan view, the hip represents the hypotenuse of a 45-45-90 triangle, and 12^2 + 12^2 = 17^2)

   I wanted to add one thing:  the top of the hip rafter will not fit within the plane of the roof if you notch it (at the wall plates) the same amount as the common rafters.  This is because the hip rafter --  having actual width of 1.5" or 3" or whatever -- is NOT a theoretical line. 

   There are two solutions.  First, you can bevel the top of the hip rafter, so that it comes to a little peak (note that this peak is, in fact the theoretical line --- this should help you visualize the geometry involved).  The more common approach is to notch out a bit extra on the hip rafter where it sits on the wall plates.  This will lower the hip rafter, and result in the sheathing contacting the left and right edges of the top of the hip rafter, with a small span across the centerline.

   Hope this wasn't too confusing.

   Ragnar