All How-To Topics
Digital Job Site
|
|
A Tale of Two Pitches: Exploring Off-Angle Roof Framing
comments (7) December 17th, 2012 in Blogs
Matt Jackson, member
Differing spans and matching ridge heights require off-angle roof framing
Overview
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...
posted in: Blogs, architecture, framing, roofs, tutorial, roof, rafter, ridge, hip, plane, plate, gable, geometry, calculation, valley
|
|
|
|
-
How to Paint Fiber-Cement Siding
Painter Jim Lacey shares some tips for caulking and painting fiber-cement siding. read more
|
|
The Digital Job Site
Get the inside scoop on how builders, remodelers, and architects use the free 3-D modeling software Google SketchUp to design projects and present them to clients.
You'll find practical advice on how to use this powerful drawing tool, and get some insight into how some experienced builders and designers have workied it into their set of everyday tools. If you are new to SketchUp, you might want to get warmed up with a few of Google's free tutorials.
Comments (7)
Posted: 3:29 am on May 15th
I respect your persistence. It brings to light more of the geometric constraints of roof framing. It also helped me to understand the point you raise: Soffit width and fascia height can be made equal by adjusting the roof pitch and rafter bearing height.
If there is viewer interest I will draw and upload a roof framing model to clarify how wall and rafter framing would be configured to meet this design criteria. I agree it would be a great resource for the learning process.
Thanks for sharing at The Digital Jobsite.
Matt
Posted: 4:11 pm on February 5th
sketchup is a great program. with a few changes on what you have made it would be a great resource to use to teach apprentices that have a hard time visualizing
Posted: 10:34 pm on January 20th
Thanks for your comments...
While raising wall heights can indeed make the fascia line up, all other things being equal, it would make the ridge heights differ by the same amount. Its a matter of choosing where to compromise in a selection of geometric constraints.
I hope you find The Digital Jobsite and SketchUp helpful in visualizing non-standard roof framing configurations.
Matt
Posted: 8:27 pm on January 14th
Posted: 7:45 pm on January 7th
Thanks for "stopping by" the Digital Jobsite. Your in-depth and wide ranging experience from work and business along with extensive knowledge of SketchUp is always an asset to the discussion here.
As there are as many ways to model things as there are to build them I hope other viewers appreciate the methods and perspective shared in your comments,I know I do.
Matt
Posted: 10:10 am on December 24th
For those with existing casual knowledge in using Sketchup, I think it is important to emphasize the point Mr. Jackson made about using the temporary top bevels on the ridge beams. Another approach (my approach) is to draw the rafters first without a ridge beam; as if they are simply mitered at the peak. Then, based on the structural ridge beam size you need draw a beam that passes through the rafters at the proper location. If you had the forethought to make the common rafters into components then you just cut one back and they all cut back.
Better yet... for anyone trying to decide whether or not they want to upgrade to Sketchup Pro version... Solids Tools make quick work of cutting complex angles on virtual jack, hip, and valley rafters.
DC
Posted: 7:50 am on December 20th
You must be logged in to post comments. Log in.