How to Build Roof Trusses for a Shed
Building a shed can be a weekend project for someone who enjoys working in the house and yard. In order to create a sturdy shed, proper framing technique must be utilized. Building a shed may require a permit in some areas, so be sure to check before starting.
Roof trusses for sheds are simple to build and will create a strong roof for a small storage building or work shop. The trusses should be assembled once the floor of the building is complete.
Here are general guidelines on how to build and assemble roof trusses for a shed:
Measuring and Materials
Each truss requires two beams and one bottom cord, which are built from two by fours. The number of trusses needed depends on the length of the building. Trusses are usually installed every 16” on center. Measure the slope of the roof and multiple that by two, and then multiply that figure by the number of trusses needed. Multiply the width of the building by the number of trusses, and then add this to the first number. Add an additional 10% to cover board feet lost in cuts.
Cutting Rafters and Cords
The upper ends of the beams are cut at forty-five degree angles. If the desired pitch of the roof is less than 45 degrees, it can be adjusted. Both ends of the bottom cord are cut at 45-degree angles to fit between the rafters and join them together. Triangular gussets made from 1/2” plywood are used to join the rafters and cords. Six gussets are necessary for each truss, and one of the angles on each gusset should measure 90 degrees, with the other two measuring 45 degrees. Gussets should extend inward past the joint of the rafters and cords and be flush with the edges.
Assembling the Trusses
Truss assembly should be done on the ground, first. Use the floor of the shed and align two rafters in a corner. Use a stop of 1” by 3” wood on each side of the corner to hold the beams in place. Make two more stops and install them flush with the bottom cord to keep it from slipping during assembly. Make sure the beams and cord fit snugly together. Using glue and screws or nails, attach a gusset to each of the three corners of the truss. Turn the truss over and attach gussets to the other side.
Installing the Trusses
The trusses are installed after the walls are framed and sheathed. One truss is attached with screws to both the front and rear walls of the building, and if the walls were framed 16” on center, one truss should attach at each upright in the wall. It is important to make sure the trusses are plumb (perfectly vertical) when attaching them to the frame to avoid gaps and weaknesses. When the roof sheathing is attached to the trusses, they should again be checked for whether they are still plumb.
It is not difficult to build roof trusses for sheds, since the area of a shed is small and a simple design can provide adequate strength. Larger structures require designs that are more complex, because larger buildings have greater stresses created by compression and tension. The principle of using triangles to distribute the stresses evenly is constant in every truss design.