We are doing a energy retrofit of a 40 year old addition on a 70 year old home. The addition had a partial basement (pond) that had poor grade externally. Poor windows below grade, and the external wall was dampproofed  with the tar emulsion of that day. Naturally leaks were almost immediate. Looking for suggestions as to best practice/materials to seal this aquarium up. My concerns are the previous coating, I can power wash it but not sure if it all will come off. Will seal the cold joint, French drain,  drain plain/dimple board or use some mechanical drain surface, waterproof the wall but not sure with what. The basement has no insulation would you add some during this process and would you tie it into the external wall insulation added later on.  area is about 800 sq. ft. floor space.