Carolyn in Montreal wants to insulate her garage so that she can heat it but it is so narrow that there is no room to do anything on the inside. Can she insulate on the outside?
As you can see in the graphic, you can easily put foam insulation of just about any thickness right on the block wall. In Montreal I would recommend two inches for an R-10 insulation. Then you can cover it with any finish you like. It could be brick like in the photo, or you could strap the wall and put on vinyl, aluminium or any other siding, even stucco. The only catch might be that in some areas of Montreal, because of the density of housing, they do not allow any siding that could spread fire, so in that case you would have to use either masonry or metal siding.