John,

Those are all "trusses", which have top chords (what the roof sheathing goes on) and bottom chords (what the ceiling attaches to).

Are truss hangers required? Depends.

Sometimes yes and sometimes no. If specified by the truss engineer, yes.

Is it "better" to use hangers? Yes. Is it "required", not to my knowledge, depends on the truss engineering.

__________________
Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
www.AskCodeMan.com