Trusses are slender elements. They are very strong when placed in the vertical position, but can be easily damaged or broken if racked or bent in the lateral direction. Damage or failure can occur at the joints (connector plates) or within the lumber members.
When trusses arrive at the job site they should be checked for any permanent damage such as cross breaks in the lumber, missing or damaged metal connector plates, excessive splits in the lumber, or any damage that could impair the structural integrity of the truss.
If truss plates have separated from the wood member beyond the limits specified in the quality control documents, under no circumstances should the loose plate be hammered back into position. This is because the grip values of the truss plate and the integrity of the lumber are likely to be affected. If corrective repair measures are required, the fabricator must be advised. In some cases the fabricator will consult a structural engineer to identify remedial measures.
Whenever possible, trusses should be unloaded in bundles on dry, relatively smooth ground. They should not be unloaded on rough terrain or uneven spaces that could result in undue lateral strain possibly distorting the metal connector plates or damaging parts of the trusses such as overhangs and soffit returns (Figure 4).
Wood trusses can be stored horizontally or vertically. If stored in the horizontal position, trusses should be supported on blocking spaced at 2.4 m (8') to 3m (10') centres to prevent lateral bending and lessen moisture gain from the ground. When stored in the vertical position, trusses should be placed on a stable horizontal surfaced and braced to prevent toppling or tipping. If trusses need to be stored for an extended period of time measures must be taken to protect them from the elements, keeping the trusses dry and well ventilated.