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 from Catie’s virtual course curriculum, we learn how to think about planes when planning and framing a hip roof. Watch her explanation in the video above or keep reading for our key takeaways.
A roof plane is the flat, pitched surface of the roof. With a gable roof, there are two planes that meet at the top of the ridge. With a hip roof, however, things get slightly more intricate.
Successful hip roof framing starts with your mindset: Instead of thinking about the roof as a collection of individual pieces (rafters, jacks, ridge, etc.), you need to think about the collective plane they form together. In other words, make sure all the pieces intersect on the same plane instead of trying to make them flush with each other.
With this equal-pitch hip roof, you’re creating four planes. Each hip rafter is positioned at 45 degrees to the ridge and common rafter. These intersections are where you need to focus your attention to ensure the four planes are flat.
In this example, when you look beneath the sheathing where the four planes meet, you’ll notice that the sheathing hangs off of the common rafter and jacks and meets at the center of the hip rafter. (Some roof framers will go a step further and make the backing cuts, so there's no air space between where the sheathing meets.) Therefore, when you install the hip, your goal is to flush the top of the common rafter with the top of the ridge so that the sheathing meets exactly in the center of the ridge. (Again, some roof framers will bevel the top of the ridge as well.)
To install the hips on this roof, you similarly need to think about where they need to intersect with the ridge and common rafters so as to create a flat plane. In this roof, the hip rafters are slightly dropped so the roof sheathing can pass over the outside edges of the hip and meet in the middle. The more precise you can be with these intersections, the flatter the roof plane will be.
For more from Catie on how to frame hip roofs, check out the anatomy of a hip roof and watch her explain the importance of triangle geometry in roof framing.