I have a 4’  exposed brick foundation wall on top of stacked rubble that I want to insulate on the exterior.

 The outer bricks are deteriorated from a lack of parging and I was planning on possibly applying a coat of lime-based parging given how soft they are.

 The concern I have, though, is if I were to install Comfortboard 80 and a cement backer over the face of the wall.  I expect I’d end up with water on the face of the parging.  I could damp proof it with drylok, I suppose, but I’m not really sure exactly what the risks are, or the best approach to address it may be.