Heavy Timber Truss / Bow String Truss Repair

Heavy timber trusses, or bow striing trusses, can usually be found on buildings constructed during the early to mid 1900's. Typically the top chord of the truss is curved and it forms a barrel shape to the roof. The trusses are usually located at 15 to 25 feet on center and they support rafters which span between them. Unfortunately, these trusses are more often than not, incapable of resisting a full snow load.

Early signs of an over stressed truss:

1. The bottom chord is cracked or split, usually at splice locations.
2. Bolted connections along the bottom chord and interior diagonal chords are splitting through the timber members.
3. The truss is crushed or rotted at the location where it bears on the exterior walls.

The most economical repair for these trusses requires adding columns to support the truss at as many points as possible. As additional columns are added to support the truss, the amount of work required to repair or reinforce the existing truss members is significantly reduced. The negative side to this solution is that the columns may interfere with the space below the trusses.

Before any repair can be done, a detailed structural analysis of the truss must be completed. This analysis may include different possible column locations and their effect on reducing stresses within the truss members. From this information, the most economical repair for the situation can be found.

We have the capacity to analyze the trusses, produce repair drawings for permit, and provide an estimate to complete the repair work.

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