How to Add Angle Supports to an Existing King Post Truss to Strengthen a Roof

Measure the distance from the base of the king truss to the spot on the rafter where you need to attach the angled truss. Mark this measurement on one of the boards.

Cut the board to the proper length, leaving 6 or 8 inches depending on the size of the boards you are using, to account for the angles.

Measure up the king truss to the distance of the size of your board. For instance, if you use 2-by-6 boards, you need to measure up 6 inches.

Measure from this location on the king truss up to the rafter, 6 inches up from your original measurement.

Mark the new measurements on the board you cut.

Cut an angle on the ends of the board, to create an angle from the first set of measurements to the second.

Slide the cut board into place between the king truss and the rafter.

Place a steel connector plate at the bottom of the angled truss, to attach it to the king truss. Hold it in place while you drill holes to match the holes in the connector plate.

Screw in the deck screws to secure the angled truss in place.

Add a connector plate to the other side of the angled truss, to further connect it to the king truss. Use two connector plates on the other end of the angled truss to secure it to the rafter as well.

Repeat the process on the other side of the king truss so you have two angled support trusses, one on either side.