What You Need to Know About the California Hip
Once you have learned all the answers the questions change, that’s the nature of life and, of course, truss designing. Especially when the variations in client requirements change depending on which region I am working in. For this article, I was to talk about hip ends.
Hips designs can be troublesome when working in multiple regions regarding the specific configuration and setbacks for the main girder. In the “Stepdown” hip type, I have noticed that the setbacks never went further than 7’. Here is a typical job:
The setback length from the end wall used to be one of the major issues for me to proactively determine the need. This was because the #1 hip girder could be 3 or 4 plies to accommodate tray/coffer ceilings. Depth could be and serious problem.
So you can understand my surprise when I was introduced to the California Hip configuration and the client asked for 8´ setback as standard condition and open jacks! A typical job could look something like this:
So, here we are with several vast differences:
- Many types of jacks, with a huge span (according to I was used to)
- Learning a new kind of framing that took more time setting up properly
- Standard frame condition mindset shift because I wanted to thoroughly understand how it works
- A new friend known as “Hip Rafter”
Well, I sent my first “California Hip” design to MiTek’s VersaTruss engineering software expecting problems, but guess what? Trusses worked with a single click. Not even adding plies was necessary, I could use a lot of 2×4 lumber for bottom chords in girders because connections were mostly nailed. The jacks only required adjustment for splicing in the biggest ones and the corner rafters worked even using smaller sizes of lumber.
Why this skeptical mindset? After a few jobs were completed, I concluded the reason was the “funny” configuration itself. The hip load is distributed among all trusses of the set and not only by the girder. The TC of every jack and the corner rafter is supported by the girder and the rest of hips trusses. This allows multiple supports and the use of bigger setbacks, so the hip trusses are supporting a small portion of each jack. A typical end jack would resemble:
In this example we can see the TC is supported by 6 bearings (each one is the TC of trusses of the hip). As reactions decrease because multiple bearing allow us to use nailed connections instead of hangers making projects less expensive.
Inputting California Hips In Sapphire
As a reminder, a way to put this kind of framing on the layout is using this icon:
After selecting, look for “Hips” and we will get this menu of options:
So far this not different what I was used to see on other kind of hips sets. A detail to be aware is the “Extension End Cut” field because here we are selecting the kind of bevel to use in the extension of the TC. The flat TC is dropped and the corner rafter stretches over that section, using it as bearing, so we must be sure there is room for the rafter to not collide with trusses. Maybe is easier to explain with the picture below on 3D:
For this particular case, customer doesn´t want any bevel at the TC extension.
In case we can´t use the framing set feature (due to a unique condition) we can put California trusses in Sapphire properly using the command:
Then we can set trusses the same way as the “Full-Truss” feature, remembering to take in to account the corner rafter dimensions and, again, the bevel at the TC. In the case on the job used as example for this post the “Set down” was 3-1/2” (308) and Square cut short for the TC bevel extensions.
Also we must be aware of the kind of rafter we are using (single rafter or stacked) in the case shown in the picture we must use a single rafter up to the face of the #1 hip girder, otherwise we´ll have an interference problem.
Is the California Hip better than any other hip type?
Depends on what your goal is! For rigidity and framer-friendliness, it cannot be beat. For overall truss cost, it is more expensive.
At the end of the day, this hip type requires a lot of attention and effort from truss designers to skip solutions used in other cases that wouldn´t work for this kind of hip set. Also, when plans have the optional ceiling conditions as vaults or trays, this corner type cannot be used.
Javier Dominguez – Design Professional
Gould Design, Inc.