I recently purchased a home that is 37 years old with plaster walls. I have now noticed that the exterior walls are very cold to the touch. Is this normal. I am thinking that there is very little or no insulation between the interior wall and the brick exterior. Is this the only possibility or am I missing something? If this is the case, do I have to tear down the plaster, insulate, and then put up drywall, or are there other options?