I am inquiring about what type of insulation that I oculd use to insulate the wall in the staircase. The lathe and plaster is removed and the double brick is right behind it so the space that is available for insulation is 1-1/2" - 2" . In other rooms of the house we have reframed inside and insulated as you would in new homes however this is not an option as the staircase isnt wide enough to reframe and lose that space.
Any thoughts?

Thanks
Tanya

is there really another choice at that width?