I am looking at a 1000 square foot home to possibly purchase. Built in the mid 70's the 4x8 sheets of siding used are now failing and exposing insulation at a few points. There is no sheathing under the siding and no house wrap or vapor barrier that can be see from the exterior. I assume there is paper on the inside of the fiberglass insulation but I have no way of knowing for sure. The structure seems to be discolored but not rotten, probably because it has plenty of airflow and time to dry out between rains. My question is, if I were to remove the siding which virtually is the sheathing, and I find that the insulation needs to be replaced, what is the best method of doing this while still using a house wrap or vapor barrier. Gutting the interior is out of the question because it's in perfect shape. Is it possible to properly insulate and vapor barrier the wall from the exterior side only? It's a fairly simple house, one big rectangle with high gable ends over a block foundation plenty high above grade.