When we removed the cement siding that had been put on, we’re guessing in the 50’s or so, we found some gaps in the siding that we attributed to wood that had been removed because it was in poor condition. Jon was the one who figured out what was missing was a trim piece that has a slanted sill-shape with a crown molding under it. He’s recreated that around the whole structure using clues from painted vs bare wood areas.
Meanwhile, the lap siding is going up on the addition, tying into the existing.