Oftentimes, MiTek engineers are getting requests for repairs of trusses installed out of plumb. This is a common installation issue and has some allowable tolerances. Tolerance is critical for both a good roofline and effective bracing. Exceeded erection tolerance can cause overloading, buckling, and possible permanent damage of the structure. Installation tolerances are given on page 11 of the BCSI-B1: Guide to Good Practice for Handling, Installing, Restraining & Bracing of Metal Plate Connected Wood Trusses. [For all images, See PDF or View in Full Issue.]
Note: Tolerances shown apply to Trusses in their permanently set position and assume the Top Chords are adequately restrained and braced by the diaphragm.
It is very important that trusses are installed straight and plumb within these limits, and for them to stay that way after loads are applied. Field conditions beyond these tolerances shall be reviewed and approved by the building designer and/or structural engineer.
For additional information, or if you have questions, please contact the MiTek Engineering department.