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, she explains how building length and total run can help you calculate the hip ridge length. Watch her explanation in the video above or keep reading for the highlights.

How do you calculate hip ridge length?

When calculating rafters, you typically use the run of the building. The run is half the span (in everyday language, we refer to the span as the width). Hip ridge length = building length - (total run x 2) + (½ common rafter thickness x 2) 

What’s the ridge?

The ridge (also called a ridge board or ridge beam) is the horizontal piece of lumber where two opposing planes meet to form a peak. 

What’s the total length of a building?

The total length of a building's walls that run parallel to the ridge (whereas span is the perpendicular measurement, and run is half of the span).

What is total run?

Total run equals the total horizontal distance from the center of the building to the outside (measured at the framing) building. Add the horizontal distance or the eave to determine the total theoretical length of the hip rafter.

Be sure to check out Catie’s anatomy of a hip roof and explanation of hip roof planes.