Behind the wall
A pipe on the upper level of a commercial facility had a small hole in it. The pipe began leaking down the wall to the lower level. In the first photo you can see how weak the wall became it was very wet. The entire wall was damaged inside. The whole side wall along the staircase was removed. Air mover (fans) were placed to dry out the wood. This is an example of a leak that you have no idea is going on until you start to notice the damage. It's a good thing the business owner noticed the wall becoming wet along the stairs.