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Bastard Hip ?

Tony_Campbell's picture

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I,m in the process of framing a new home with a variety of roof types. I have no problems with gable framing, or standard hip framing but I've run into a dilema. I have a hip roof that runs perpendicular to the main gable roof. The ridge of the hip roof intersects the slope of the main gable at the half way point. So far no problem. Here's where I start to get lost. The two sides of the hip roof projecting from the main roof, which is a 12/12 pitch, are at a 7/12 pitch but the front of the hip roof is at a 12/12 pitch. Is the seat cut of the hip rafter half the difference of the two pitches or 9.5/17? Also, when I look at the print, the hips don't fall directly over the corners.Is this what is called a bastard hip? If not , it should be. Any help figuring these hips would be appreciated.

(post #160686, reply #1 of 6)

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Tony,

Here's a good place to start.

< Obsolete Link > TomC "How do I cut that bastard?" 3/31/01 7:44am

Ken

(post #160686, reply #2 of 6)

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Ken and Joe, Thanks for the info. Your posts even use the same pitches I'm fighting with! As I stated in my last post, the hips don't appear to sit directly on the corners of the walls. Is this a common occurance when 2 different pitch roofs meet at a hip? If so, what determines the intersection point with the walls?

(post #160686, reply #3 of 6)

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Tony,

There's basically 2 different ways to frame the irregular hips and valleys.

If you frame them directly over the corners, which is quite often done, then the overhangs will be unequal.

If you wish to keep the overhangs equal for both the 7/12 and 12/12 rafters, then you have to move the hips onto the (steeper) 12/12 plates away from the corners, and offset the valleys also. In addition, you must raise the 12/12 plates by a certain amount, from hip to hip.

The measurement for offsetting the hips and the valleys, and raising the plates, is determined by the amount of overhang.

If you take the time to read through the thread that I recommended, all of your questions, (as well as some others that you didn't know that you had), will be answered.

Good luck,
Ken

(post #160686, reply #4 of 6)

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As I've said before, and you'll probably find it in the above discussions. Buy the Roof Framer's Bible, by Barry Mussel. Haven't had a roof question since I bought it.

(post #160686, reply #5 of 6)

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Just wanted to thank you, Ken and Joe, for the info. You definately saved some pretty nice 2x10's from becoming kindling. Tommy, I have the Roof Framer's Bible on order. This project still isn't easy but it's MY HOUSE and it WILL be done right. Joe, your web site is outstanding!

(post #160686, reply #6 of 6)

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I,m in the process of framing a new home with a variety of roof types. I have no problems with gable framing, or standard hip framing but I've run into a dilema. I have a hip roof that runs perpendicular to the main gable roof. The ridge of the hip roof intersects the slope of the main gable at the half way point. So far no problem. Here's where I start to get lost. The two sides of the hip roof projecting from the main roof, which is a 12/12 pitch, are at a 7/12 pitch but the front of the hip roof is at a 12/12 pitch. Is the seat cut of the hip rafter half the difference of the two pitches or 9.5/17? Also, when I look at the print, the hips don't fall directly over the corners.Is this what is called a bastard hip? If not , it should be. Any help figuring these hips would be appreciated.