Insulation, Radiant and Vapor Barriers - R 7?

A year ago I Re did the kitchen. When doing so I openned a short 4 foot section of an outside wall and found that the insultion (new new new 1960) was a corning product of about 2 inches thick and labled R-7. it was stapled about half way into the stud spacing leaving about two inches between the vapor barrier and the plaster wall. This I filled with a 2 inch styrofoam board insulation from the depot. I have a few questions and the need for some advice. First I know that the gap between the barrier and the plaster makes for a great chimney like path for fire but concidering the flamability of styrofoam did I make a mistake? and what should be done on the rest of the house?

Thanks for your time

John

I would recommend taking out the old insulation and installing all new insulation. The reason for this is the vapor barrier. In the first action you took, the vapor barrier is inbetween the layers of insulation. Though the probability that this will cause a moisture problem is low because you use foam board, I would not advise you to do the same throughout the house.

You are correct about the chimney effect, however, there are probably fire stops throughout the wall structure. Example, top and lower plates of wall framing. In my opinion this should not be a concern for you. The chimney effect you are concerned about has to deal with balloon framing which was not used in the 60's.