Now that the poles are in place and the side purlins are attached, it is time to build the trusses for the roof of our pole barn. I could either buy or build the trusses – I chose to build. There are a number of places that sell pre-built trusses at a very reasonable cost, but I decided to build my own so that I could build them exactly the way I wanted and video the process. Pre-built trusses are only slightly more expensive than building them myself, but I wanted the experience of building my own pole barn and felt I could design and build them to a bit higher standard than just purchasing a truss.
The first step was to design a truss. I did a Google search and found a nice web site that will take in your specifications and design a truss to meet the engineering loads you request. Medeek Designs is used by a number of engineers to design trusses for all types of buildings. My trusses are pretty straightforward so I plugged in my needs into the calculator and it gave a truss design along with a 3D CAD drawing I could then load into my CAD drawing software, SKETCHUP, which I highly recommend. I used the design in my drawings and then printed out the truss dimensions so that I could build the trusses in my driveway.
To start the truss building process, I knew I needed a perpendicular line that I could use as a template to build each truss. I first laid out a 30′ straight line using my string chalk line. I marked a center point and then needed to create a perpendicular line for the center of the truss. Simple high school math came into play. See my video on creating right triangles and squaring buildings using math.
Once I had a template drawn on the concrete for each truss, it was then a matter of cutting the boards to match and plating the truss together. You can see how I do this in the video below.
Below is a video I created showing how to use simple high school geometry to calculate perpendicular lines that are square with your baseline.