Have decided to insulate walls of 1958 brick house in Ontario, Canada- which has little to no insulation in the walls.
Having difficulty determining the layers I must include to properly insulate and finish each of the rooms.
The exterior of the house is brick, followed inside by a black tar paper.
I have roughly 2 inches of space to deal with/use.
I am planning to pull current plaster walls down.
Do I consider the tar paper a water barrier or do I need to add?
Not sure of the layers I should be ensuring.
Thanks for reply

Before you pull all the plaster down, consider having foam sprayed in the wall cavity. They will drill a small hole in the bottom on the cavity and a small hole in the top, pump poly foam in as the pipe is slowly pulled out. Even with this you are only going to get about R-12 for 2 inches. Most heat is lost through the attic. Make sure you have R-48 or so up there.

I agree, replacing the walls just to get insulation into them is not cheap, easy or quick. The fpoam will not likely be something you will get at HomeDepot or Menards. Do not try spraying in GreatStuff or anything like that unless you want to see your walls bulge and pop into the room

Thanks all!