GBA, It’s a 1920 double brick house with 2×3 and lath & plaster with no insulation near Toronto (climate zone 5/6).

Brick is in good condition with big enough overhangs (2+ ft) and good water management. Air leakage was 6.5 ACH50.when I bought it 4 years ago but it’s down 3.5 now (windows and spray foamed the unfinished basement). I’m aware of the risks related to insulating brick buildings (thanks to GBA articles). I also know that closed cell spray foam is the recommended method for brick but that’s not a route I’d like to use. Is dense pack cellulose an option? If not, are the concerns: 1) brick will be colder so air leakage will lead to condensation; 2) vapour drive will lead to cellulose getting wet; 3) other?

How will dense pack cellulose impact a double brick wall in a cold climate?

Is there a better option that doesn’t involve opening the walls?

Thanks, Drew