How Are Trusses Fixed to Wall Plates?

Bearing Points

• There are two types of bearing points or spots where a truss intersects with the cap board on top of an outer wall. Some trusses have bottom chords, which rest on the wall plates; other styles have bottom chords that go inside the wall caps with the rafter chords resting on the cap. Trusses also rest on top plates of internal walls at various points.

Three-Nail System

• Trusses must be lifted to the roof, set upright and plumbed with a level so they are perfectly vertical. The traditional fastening involves three 16d (3-inch) nails per truss end. Two are driven at an angle, toenailed through one side of the truss chord into the wall cap. A third nail is toenailed, either through the end of the truss chord or from the other side of the chord. Both truss ends are nailed to outer wall caps.

Metal Ties

• Some trusses are fastened to wall caps with metal connectors called ties instead of framing nails. Ties are galvanized steel brackets, which are nailed flat to the top of the wall caps and vertically into the sides of the truss chords. Several styles are available. Some just go up the side of the chord, while some go to the top of the chord and overlap it at the top. All ties are nailed in place, typically to the wall cap first, with the truss then set inside the bracket and plumbed for nailing.

Other Ties

• Trusses fastened to caps with the three-nail method should be further secured with hurricane clips. These are metal brackets, which overlap cap boards and truss chords, are fastened to those members with two nails on each end. All trusses also should be fastened to top plates of internal walls with truss clips, which are L-shaped steel brackets that are nailed or screwed to the plates and to the bottom chords of the truss.