How do you build a gable on an existing roof?

How do you build a gable on an existing roof?

Adding a Gable Roof to an Existing Roof To tie into the side of an existing roof, put a new roof truss on the walls of the addition, brace it upright, then snap chalklines on the shingles to mark the center line of the new roof valleys, where old and new roofs will connect.

How is a gable roof supported?

In conventional gable-roof framing, the slope of the roof is formed by rafters that run diagonally downward from the peak of the roof to the tops of the exterior walls of the building. The upper ends of the rafters rest against the ridge board, a horizontal framing member that runs along the peak of the roof.