Hi, I live in a basement flat. At the front of the flat there is a door leading to a small storage area, created by the stone steps leading up to the ground floor flat entrance from the street. The problem is that when it rains i get water dripping in between the steps and into the area. It looks like the underneath of the steps (inside the cupboard) has previously been coated with a thick black paint but in areas it is starting to come off. I was wondering what is the best method to waterproof an internal area like this? It is quite an uneven surface and awkward to get into, so some sort of paint or spray would be best. Also I wouldn't be free to paint the outside surface of the steps.
Any ideas welcome. Thanks