HELP! I have a leak in an interior wall the leak is out of my reach and the wall has serious damage. I have limited finacial resources and need to fix the problem quickly and inexpensively. The wood on the back side of the wall (basement access) is soft and looks rotted and the plaster is coming loose from the interior wall and has a growing stain that is seeping through from old wall paper. I have access to the upstairs plumbing through an attic and the leak is not within reach of either the attic nor the basement walls.