1. The Right Angled Triangles in a Hipped Roof M. S. Martin May 2007 reviewed April 2010

2. Basic Triangles for the Hip We use our basic rise per / m run triangle for the hipped roof as well, for our common rafter bevels and calculations. In addition to this we use a 2 nd triangle to represent the hip per / m run of common rafter The following pictures have been drawn with a ½ span of 1.0m to make this easier to understand.

3. First lets look at the plan view of our hipped roof. Now lets look at this in an isometric view, showing our basic triangles First the Common Rafters Second the hips

4. The Common Rafter You already know this from the gable roof. The common rafters in the hip are the same. Lets use an example of 30° Tan 30 = 0.577 Which is the rise per / m run of common rafter The true length per /m √0.577² + 1.0² = 1.155 1.0 0.577 1.155 30°

5. The Hip – per / m run of common rafter For the hip we use the rise per / m and the plan length of hip Plan length hip per / m run √1.0² + 1.0² = 1.414 True length hip per / m run √0.577² + 1.414² = 1.527 0.577 1.414 1.527 0.577 1.0 1.155 30°

6. Simplified Handout The handout opposite should make a good reference guide for this. True length of hip per / m run of common rafter