How to Build a Steel Roof Truss

Lead Image
  • 4-6 hours
  • Advanced
  • 2,000-20,000
What You'll Need
Steel roof truss beams
Steel truss plates
1 1/2 -inch galvanized steel bolts
Galvanized nuts
Circular saw
Steel-cutting blade
Measuring tape
Drill bits
Power screwdriver
Galvanized deck screws

A steel roof truss is used to replace a typical roof truss which is made from wood. You may also find steel roof trusses in larger buildings or commercial projects. The purpose of the truss is to support the weight of the roof and keep the walls steady. A steel roof truss, like a wooden one, is triangular in shape. They are installed the same way as a wood truss and do the exact same job. The major differences between a steel roof truss and a wood truss include durability, strength, and resistance to the elements. The article that follows will explain how to construct a steel roof truss.

Step 1 - Size the Roof Truss

The span of the roof is what determines the size of the roof truss. You need to measure the width of the roof area as well as the height of the roof’s peak. You can then determine the size of each side of the roof from the peak. Since the steel roof truss is a triangle, these measurements are crucial. You want to have three pieces of steel initially, the base and two sides. Use the circular saw equipped with the steel-cutting blade to cut them out or have the store where you purchased the steel cut them for you. You also need to measure from the base to the peak and have a piece cut to that length for the brace. Each split section will also have a beam coming from the bottom corners to the top-center.

Step 2 - Build the Roof Truss

With the pieces cut, you can now assemble the truss. The truss is built on the ground and is then raised and affixed to the frame of the home or building. Place the base on the work surface and then place a truss plate at the end. Use the holes and guide and make a pencil mark. Drill the holes out and then place one of the sides also marking the holes and drilling them out. Place the truss plate and then install the bolts. Fasten them with the nuts making sure they are tight. Repeat with the other side of the roof truss. Place the support beam in place in the center followed by the other two from the bottom corner to the top. Add truss plates where these beams dissect. Flip the entire roof truss over and then add plates to this side.

Pro Tip: To torque a bolt without a torque wrench, snug the nut down, then give it a quarter turn more.

Step 3 - Attach the Roof Truss

Place the assembled on the frame of the roof using the level make sure it is straight and even. The building codes will determine the amount of overhang you need based on the size of the roof. Attach the roof truss to the frame every two feet. Use galvanized deck screws that are three inches long. Repeat as needed depending on how many trusses you have.