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").
In this video, Catie explains how simple geometry can help you calculate the length of a hip rafter. Watch her tutorial video above or continue reading for our key takeaways.
In this example, we have to adjust the overall length for “reality” after calculating the theoretical roof—which is simpler than it might sound. The calculation comes down to basic geometry. For common rafters, we first calculate the theoretical length of the hypotenuse (which extends to the center of the building). Then, you need to adjust for reality (see video instruction).
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 hip ridge length.