I am working on painting a bedroom where when we removed the bed from exterior wall and wall paper we noticed mold. There is no insulation between the walls as the house is over 60 years old. My question is Id like to see about filing between the walls from inside since I need to do some minor repairs on wall before painting. And do not want to go through the stucco from outside making holes. is there a inexpensive way to drill and shoot either foam or ? That will help prevent mold and also insulate some??