Trusses Again

Well, back to this.

To get the terminology, diagrams help.  The same site implies that sistering the bottom chord is sufficient to reduce sag: "Undersized bottom chords should be stiffened to prevent ceiling sag and cracking of ceiling finishes. Adding a second member to the bottom chord would normally be satisfactory."

A FH blog post had some conflicting advice.  The solution I thought was most sensible was in the comments: "run a beam under the joist,no post needed, create a beam pocket at one end with double 2x4 cripples and 2x12 double simpson hanger at overhead header. Use 2x12 and 1/2 plywood glued with PL400 and your done."  Except that's probably to reduce the span; my issue is that running something cross-wise isn't an option.  It could work for the shelving, perhaps.  I'd have to remove the drywall to install the trimmers for the beam pocket, though.

A JLC article suggested a composite beam along the lines of the above.  Sounds expensive.

Perhaps I should go find myself a structural engineer to bother regarding my problem.  Expertise ain't free.