Short version: Water is appearing from underneath a built-in bookshelf/wall in the basement. Could it be coming from, perhaps, a crack in the floor?
Director’s Cut: Around 15 years ago I built a wall to sub-divide a basement space. Then I made and attached a bookshelf to one side of the wall. The unit is around 10 feet wide and 18 inches deep, floor-to-ceiling.
Yesterday I noticed a small amount of water leaking out from underneath. I figured one of the overhead pipes was dripping. Upon further inspection, I cannot find any dampness from above; it actually seems to be rising up from underneath the bookshelf. It is a significant amount - the drywall on the reverse side is moist for about an inch up from the floor.
It sure looks like I’m going to have to do some demo to find the source of the leak.
My question: is it possible it could be coming from below? What would cause this? I am not sure if I drove fasteners into the concrete floor or not, but if so, could this be something to consider? How thick are basement concrete floors, anyway?
Any thoughts appreciated.