A Tale of Two Pitches: Exploring Off-Angle Roof Framing
Although uncommon, there are situations where architectural parameters require “off angle” hip and valley roof construction. The most common parameter is to maintain an equal ridge height over building sections with differing spans. To maintain a consistant ridge height in these situations the roof pitch must be adjusted. Another by-product of this roof configuration is varying soffit heights and widths which require further design decisions.
This first video shows how the finished roof planes in off-angle roof construction will look when completed. With the Orbit capability of SketchUp we can check out some of the various roof features as well as get an overview of how dimension/angle factors influence the resulting configuration.
Peeling an Onion… in Reverse:
It was fun to “build” this roof framing model considering the Great Weather, Straight Lumber and a fully funcional Board Stretcher available at The Digital Jobsite. As I recall, the last time I worked on a real roof like this it was cold, VERY windy, and the lumber wasn’t straight.
Checkout this next video clip to look into the what and why of soffit conditions generated with off-angle roof construction. We’ll also get a look at how actual rafter framing would look on such a roof. Using SketchUp’s Layers feature is not unlike peeling layers of an onion (except I hope shortcomings in my video production won’t bring you to tears) so we can get an up-close look at how various framing components fit together.
More to come?
There’s way too much material on this topic to cover in a single blog post but SketchUp works so well as a teaching tool for this sort of carpentry that an introduction to the subject seemed a good starting point. If viewers express an interest in other aspects of this subject such as:
How to create an intricate roof framing model
How to derive rafter dimensions and angles from a 3D model
How to design roof configurations using 3D modeling
I’ll consider expanding the subject (within the constraints of the contents of my noggin) in future posts so let me know by posting comments or questions.
Thanks for stopping by The Digital Jobsite…
Achieving even ridge height requires non-standard rafter cuts
Differing spans and matching ridge heights require off-angle roof framing