Re: Ijoist rafter tie into existing roof?
Why TJI's? LVL's won't work?
Seems like the workarounds to adapt TJI's as rafters will eat time and eliminate the savings.
Never having used them as rafters, my bias is showing.
The Issues I'd worry about are 1) added load to the existing roof from the flatter roof. 2) ensuring perfect bearing/distribution on the existing roof@ TJI. The heel especially needs to be perfectly supported, shimmed as needed so there is no float. I guess that's why you're gusseting with plywood there.
3) same at the birdsmouth cut and the soffit/fascia details. All that fiddling to adapt the TJI, more time/effort beyond solid lumber; unless there's no overhang, in which case go for it!
Remove not the ancient landmark, which your fathers have set.