Open Web Truss Size and Spacing
Builder has proposed using 14" open web trusses 19.2" on center for all floor joists except above the family room due to a long span of about 20 feet. There, the engineer recommended the same open web truss size, but 12" on center. As an alternative, the engineer proposed 18" open web trusses at 16" on center in the family room and 19.2" on center everywhere else.
Builder wants to go with 14" OWTs everywhere. I am concerned that the smaller joists may not provide as much sound dampening and sturdiness as the 18" OWTs.
I am also concerned that the smaller floor joists may not accommodate larger AC ducts. What do you think?