Evidence of Leaking Shower
I was called out to clean this shower and I stopped dead in my tracks. This shower displays all the classic signs of water leakage leading to damage.
I noticed the sheetrock and paint damage immediately adjacent to the shower curb, classic indicators of water wicking upwards out of the shower pan. When the weep holes are blocked in the subdrain, hydrostatic pressure takes the path of least resistance. This water path travels through the curb and shows up visibly in the areas most susceptible to water damage, in this case, the sheetrock walls and paint. You can read more about this dilemma and solutions here.
Here you see another indicator of water buildup below the surface of the tile. On the right-hand side of the curb you can see the tile trim pieces are separating outward from the field tiles, causing the grout joint to widen. Many people with leaking showers expect to see pools of water as evidence of the leak. However, in most cases the water damage is happening below the surface of the tile and mortar, causing swelling to the wood structure of the curb.