Gap at the end of my basement joists. Spray foam or Caulk? – GreenBuildingAdvisor

Hi, I’m cutting the foam for my rim joist insulation and I noticed that I have a gap in between the end of my joists and the rim joist. The gap is about 1/2″ or more on some. 

1. Is this normal for house construction circa 1900? If so, I’ll be thankful for the thermal break and applaud the forward thinking builders of 1900. 

2. Should I shoot some fireblock spray foam in between the end of the joists and rim joist? I feel like all my work won’t be as airtight if I don’t. 

There are issues with attaching images at the moment, so I can’t upload my picture yet. Here is an exaggerated depiction.  Evidently underlining also doesnt work. Under the gap is the sill plate. 

___Joist________| gap| <– Vertical rim joist