Damp proofing/tanking a basement

Question

The plaster on one wall of my basement has blown and come away from the wall. I've stripped it all off which leaves a layer of concrete painted with bitumen. What's the best method for sealing off more water coming in? When I started to strip back the bitumen layer I hit a pebble!! It appears that there is not brickwork down there instead perhaps the foundation? The wall also has a custom built stair case running up it which complicates things further.

Answer 1

Sealing basements so water doesn't come in starts from the outside using curtain drains to lower the water table. For bitumen or any other wall sealer to work effectively, it's applied to the outside of the wall.