Sometimes the simplest looking plans result in a special sort of brain teaser for the truss designer. Its seems that many times what looks good and what a homeowner desires is the opposite of what makes the most sense structurally. It is the truss guys “job” to bring these two worlds together in a safe, simple, and satisfactory way.
Recently, I worked on a job that at a glance seemed straightforward but, as I put the pieces together, it took a twist towards the cantankerous side of component design. The elevation is fairly simple. The walls do not have many corners. There is only one pitch (6/12), overhangs are short and heels are all standard 2×4. The loading and wind speed are typical.
There are four different vertical tray ceilings in this home and the architect pushed them to the maximum size that will fit inside the roof. I created a tail bearing truss to accommodate this where the span is a little long; it reduced webbing and steps in the bottom chord. That makes it shop friendly and lowers the risk for the component manufacturer. If desired, I could have added filler to create the profile for the trays, but it wasn’t required in this case.
One of the tray ceilings is directly underneath the corner of the upstairs. I had to create girders to carry the wall, floor, and roof above with the profile of the tray built into the bottom. This is one of those creative moments when you’re not too sure what is going to work. Fortunately, these girders worked without too much trouble.
Another issue I encountered on this job is that the corner of the second floor is in the middle of the garage. The floor is only 16” deep so I ended up with a lot of plies on my girders. I made a set of combination roof and floor trusses. The loads from above have to be placed manually and the trusses have to be run with both roof and floor loads (including wind load). Take a look at the cross section below
I run into lots of issues like this when designing custom homes. I have learned to appreciate it over the years because it keeps my job interesting. I love the challenge. I love the sense of accomplishment when I get something to work that seemed undoable at first glance.
What kind of unusual designs have you seen over the years?
Gould Design Inc.
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Stay tuned for Part 13.