Trusses are typically fixed to external walls by connecting them to a wall plate, which is then secured to the wall structure.
Primary Methods
The most common method for fixing roof trusses directly to the wall plate involves using proprietary truss clips. These clips are designed specifically for this purpose, providing a secure connection that helps resist wind uplift and other forces.
The wall plate, which serves as the base for the trusses along the top of the wall, must itself be securely anchored to the masonry or other external wall structure. The reference specifies two key methods for fixing the wall plate to the masonry:
- Using galvanised straps: These metal straps are fixed to the wall plate and embedded or anchored into the masonry at regular intervals. The reference states these straps should be installed at no more than 2-metre centres.
- Using bolts: Alternatively, the wall plate can be fixed using bolts that pass through the plate and are anchored into the wall. The reference specifies that these bolts should be installed at 1.2-metre centres.
How the Connection Works
Effectively, the truss is fixed to the wall plate using clips, and the wall plate is then fixed to the wall using straps or bolts. This two-step process ensures the entire roof structure is securely tied down to the building's walls.
Here is a summary of the key components and connections:
- Truss: The triangular framework forming the roof structure.
- Wall Plate: A timber beam laid horizontally along the top of the external wall.
- Proprietary Truss Clips: Metal connectors used to fix the truss to the wall plate.
- Galvanised Straps or Bolts: Used to fix the wall plate securely to the external masonry wall.
This combination of truss clips connecting the truss to the wall plate, and straps or bolts connecting the wall plate to the wall, forms the essential tie-down system for the roof structure.
