Just a crazy idea. What about using the Black and Decker IR thermometer and Light Painting time laps technique?
Look up "
Light Painting" in wikipedia(i would post a link but I can't yet)
If you did it at the right speed you should be able to still see the parts of the wall and what was leaking. by doing a long exposer and moving the thermometer it should make the parts glow red, green or blue.