Tackling rim joist seal and insulation with BCI blocking – GreenBuildingAdvisor

BCI joists are blocked at rim joist with BCI cutoffs, leaving a 3/4-1” air gap between the block and rim joist (due to outward facing half of BCI flange). Considering two options for sealing and insulating: (1) fill void behind block with closed cell foam and then potentially add mineral wool on the inboard side of the block, or (2) leave the void behind the block and just spray foam around foam board like normal, on the inboard side of the block. Climate zone 7, outward from rim joist is CDX then housewrap. 

Photos attached of the block alone and then two examples of spray foam option. 

Thanks much, Ian