The most difficult part of a truss repair is getting the necessary information! Here are the five things an engineer needs in order to efficiently design a metal plate connected wood truss repair:
1. The details of the original truss
Ideally, the original truss design drawings, which describe the assumptions and considerations (such as loading, material properties, etc) that went into the original truss design, would be supplied along with the request for repair. If those cannot be found, a detailed description of the truss in question along with photographs and descriptions of the truss materials will be needed to create a new truss design drawing. From there, an engineer can look at the various forces and design a sufficient repair.
2. Locations and descriptions of the damaged or overloaded portions of the truss
Not all types of damage on a truss can be repaired the same way. A connector plate that has popped off will probably require a plywood gusset repair. A cracked member could probably be handled with the addition of dimensional lumber scabs attached to the front and/or back. Also, there may be repair considerations in one location that are not present elsewhere (see Obstructions or constraints below). Knowing both the location and extent of the damage is critical for designing an appropriate repair.
3. Obstructions or constraints
Some repair designs are impractical if the truss to be repaired is confined to an area where the repair material cannot be realistically installed. For example, a gable truss with a broken web will likely require a beefier scab member attached with more connectors to a single face of the broken piece instead of scabs on both front and back that would be sufficient for other trusses.
4. Available materials/resources to perform the repair with
Knowing what materials are available at the job site will help an engineer design the repair that is most practical to apply on location. Knowing what sheathing material is on hand or if a local truss manufacturer is available can help determine if a replacement or scab truss may be the best option for an efficient repair.
5. Loading and building code requirements
Finally, if the truss being repaired is required to comply with newer loading standards or building codes than the original truss was designed for, an updated truss analysis and design drawing could be needed to understand what reinforcement (if any) is needed to bring it up to code.
Being sure to communicate all of the above information when requesting a truss repair will ensure a better outcome and turnaround time for your repair. If you need to repair a truss and don’t have a truss design drawing or if you need a truss evaluated under additional loading conditions, let Truss Pal create one for you!