We have been working on some repairs to a heavily modified frame this week. Here we removed the steel beam that picked up the ends of the joists and replaced with a new oak mid-rail.
The engineer specified 12” x 12” for a 14ft span. Which is, well, big. Air dried oak just to be sure we blunted our chisels! Every joist has been carefully scribed around to ensure a good fit.
Either end there are to be inserted posts as not to load the existing structure.