I live in a solid brick 1920's home in Montreal Canada...and there is no insulation any exterior wall. One room is particularly cold (my kids room). So i ripped off the plaster and am planning on building a 2x4 cavity for bat insulation in(R14). My questions are as follows..
1- do i build the 2x4 structure up against the bricks or do i leave a one inch cavity for air circulation?
2- i'm thinking of a plastic vapor barrier behind the new drywall and ashalt paper facing the bricks for an air barrier...is this ok?

Thanks!