We very often get asked if a basement or cellar can be waterproofed by applying a coating to the inside face of the walls. Putting aside the fact that solution does nothing to prevent seepage at the joint between the walls and the floor, it’s also actively destructive if the foundation walls are masonry. Water will build up at the coating outside face – i.e., within the masonry – and damage the masonry.
The picture above shows the inside face of a brick foundation wall that’s been given an impervious coating. The broken area was a smooth bulge in the coating, and the brick that’s been exposed by breaking the coating has the cohesiveness of beach sand.
Don’t do this.