The trusses on a shed are one of the most important pieces to design. They consist of two rafters, which will hold up the roof of the structure. After they are finished, the trusses are lifted and installed on top of the shed frame. The number of trusses you need depends on the length of the shed. The longer the shed, the more trusses you will need to make. The good news is that trusses are fairly simple to construct.
Start by getting the measurements for the slope of the roof. This will be the length of the rafters. If the roof has a longer slope on one side of the shed, one of the rafters will be longer. Decide on the number of roof trusses you will need, then double the number to get the number of rafters you will need to build the trusses.
Cut each rafter from a 2-by-4 piece of wood. Cut them to the length you need and add a plumb cut to the top ends. A plumb cut is a 45-degree angle cut.
Cut out the portion of the truss known as the bottom cord. This section connects the two rafters at the bottom. They are also cut from 2-by-4 pieces of wood and are cut at a 45-degree angle at both ends.
Create the gussets. The gussets are 1/2-inch thick pieces of plywood that will cover the three ends of the trusses. One gusset will cover the top of the truss, while two others will be attached to the bottom ends. You will need a total of six for both sides of the truss. Cut them in triangular shapes so that they are long enough to cover the joints between the rafters and the bottom chord.
You can now begin to assemble the truss. The best way to do this is by assembling it on the floor of the shed that is being constructed. Take the two rafter pieces and lay them on the corner of the floor. The peak of the rafters should meet at the corner. If the 45-degree angle at the top was cut correctly, the two rafters will fit together. Now slide in the bottom piece, so that its angled cuts fit flush with the bottom of the rafters.
To make sure that the rafters and the bottom chord fit together and attach securely, use end blocks and stop blocks. The stop blocks are small 1-by-3 pieces of wood that are screwed on to the side of the shed floor. A portion of the block will come up over the floor, which will secure the rafter in place and stop it from slipping off the foundation during assembly. Nail two on each side of the rafters. To keep the bottom chord in place during assembly, take two more 1-by-3 pieces of wood and screw them flat right below the bottom chord.
With the blocks in place and the truss firmly set in place, begin gluing and nailing the gussets to the corner. Attach a gusset at each corner, including the top. After the glue dries, turn the truss over to the other side, secure it between the blocks, and attach the next three gussets.