Our c. 1875 Italianate is balloon framed. What would be the rim joist spaces between the floor joists in the basement are filled with brick and mortar in some places, and in others (where plumbing or electrical was run) the brick and mortar was removed. I assume one of the reasons for the brick and mortar may have been as a fire prevention step. However, my question is about insulation of this space. Should I leave the brick and mortar in place? Where it was removed, what is the best method of insulation? I have seen suggestions of using EPS foam cut to shape and foamed into place, but is that the best method given the balloon framing?
I should mention here that somewhere in the past the walls were blown full of cellulose insulation, which is falling out of the spaces where the brick was removed.
Thanks for reading this and making suggestions.