Frequently Asked Questions
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There are many factors that affect these limits, such as production shop capacity, job site access, and shipping limitations. Therefore, discuss options with your preferred joist manufacturer.
Seat depths at the high end of joists shall be increased according to SJI tables 2.2-2 & 2.2-3. This ensures proper clear bearing and working point.
It is best if the structural drawings provide all necessary dimensions and joist depths. This ensures there are no questions or misunderstandings.
To remove this thrust force, a slip connection should be used at one end of the joist. If diaphragm forces collected in the joist top chord need to transfer to the structure, alternate which end of the joist has a slip connection.
Standard SJI camber may not be ideal. Consider the transition between special profile joists and other areas. Specify zero camber, or specific camber requirements, as needed.
Provide a detailed load diagram or specify the joist as ‘LOAD / LOAD’.
SJI designations (e.g. 20K4, 44LH09) shall only be used for single pitch and double pitch joists if the pitch does not exceed 1/2 inch per foot.
Bridging is only designed for stability of the joist system. Additional bracing requirements shall be designed and sized by the engineer of record. Bracing material is not supplied by joist manufacturer.
Single pitch = depth at mid-span
Double pitch (gable), bowstring, scissor, arch = depth at ridge
For any joist where the center of gravity is above the support point, all rows of bridging should be bolted cross bridging. The number of rows will vary with length, pitch and weight of joist. A joist manufacturer can give direction on this.