Our house was built in 1957. It is a brick, 1 story, low-pitch roof house w/ a crawl space located in Salt Lake City, Ut. We are working on insulating it. Today we began to drill holes in the sheet rock in order to blow insulation into the walls, which currently have zero insulation. However, once we started drilling holes, it became apparent that there is only 1 1/2" of air space between the interior sheet rock and exterior brick. What is the best way to insulate this narrow space? We were planning to blow fiber-glass insulation into the cavity at 1.5 lb/ ft^3, but we are at a loss of what to do now. Please help!
Note: The masonry walls are load-bearing, with sheet rock attached to furring strips.