My son recently bought a house built in the early 20's. A real carpenter special. Now that he completed the upstairs renovations, he is attacking the basement.
The previous owners covered the foundation walls with 1/4 inch plywood. When we removed the plywood we discovered that all the foundation walls were covered with black tar, probably used as a vapour barrier. However, in some areas the tar is coming off and the cement is crumbling like powder. The same situation occurs wherever we remove the tar. The foundation is deteriorating.
What can be done to stabilize the situation before installing a polyethylene vapour barrier and drywall?