We have french doors opening onto a concrete stairwell that is faced on the top with brick. The brick has stained the concrete in a veining pattern, and while I have no inherent problem with the look of weathering concrete, it really doesn't go well with the interior of the room. We would like to paint or stain the wall facing the room with a mural or something pictorial and my questions are: is it necessary or even possible to waterproof this wall considering the rainfall in Virginia, its connection to a larger concrete sidewalk network and the fact that it is backed by a garden? Peeling paint on concrete is really ugly, so what will keep this from peeling? Will stain cover the brick stains? Any help y'all could give would be most helpful. Thank you!