We have an approximately 100 year old house. The foundation is brick. The parging on the inside walls of the basement is crumbling in some places and is easily removed down to the brick. Also,gaps exist in mortar joints between some of the bricks. I want to repair these problems but am unsure how to proceed. Do I need to use a special mortar, matched in some way to the existing mortar? Also, how hard should I work to remove the existing parging for repair? Finally, is it necessary to replace the parging in terms of the structure of the walls, or is the parging just cosmetic?
Thanks for your help.