We’re lucky to have relationships with the expert instructors and craftspeople at Seattle Central College’s Wood Technology Center. In this video series, Catie Chaplan, a veteran instructor, guides us through some of the foundational carpentry concepts and methods for framing a basic equal-pitch hip roof, as taught in the center’s curriculum.
Catie is dedicated to teaching the next generation of highly skilled carpenters. As a professional builder for 31 years, she's worked for general contractors, boat builders, and cabinet shops, and has owned and operated a residential design-build company in Seattle since 2002. She's been an instructor at the Wood Technology Center for the past 25 years, where she currently leads the carpentry program and teaches computer-aided design (CAD) and computer numeric control (CNC) classes.
Throughout the Framing a Hip Roof series, Catie shows us how to calculate theoretical hip roof framing (meaning that the calculations go to the very center of the roof), then how to adjust those calculations for the thickness of the materials used in different parts of the roof where pieces come together (this is called adjusting for "reality").
Today, Catie shows us how to adjust hip rafter head cuts to correctly fit between two common rafters. Watch the video above or keep reading for our key takeaways.
The final calculation you’ll need to make when framing a hip roof is adjusting the head cut on the end of the hip. The calculation for the length of the hip goes to the very center of the ridge. In a framing scenario where you have three king common rafters extending to the ridge, the hip fits in between with a double-cheek cut. That means you actually need to shorten the hip rafter head so the very tip of the rafter fits in the intersection between the three rafters.
There are several different ways to determine this cut. In this example, Catie uses a construction calculator to determine this cut. The hip/valley calculator function automatically takes the run of the building, rotates it 45 degrees (along the hip rafter), and factors in the pitch.
To then figure out how to shorten the hip rafter along the diagonal, take half the width of the ridge and use the pitch and hip/valley functions to multiply the run by the pitch. The result will tell you how much to shorten the hip rafter along the diagonal.
For more from Catie on how to frame hip roofs, check out the anatomy of a hip roof and her tutorial on how to calculate the length of a hip rafter.