Some pics of common shower problems

Moldy corners and calcium clogged drain

Calcium in the stone's pores 

Discolored bottom row of tile

Well Jen, the most popular style of shower in our area is the traditional PVC drain that clamps to a 30 - 40 mil. liner. This liner runs up behind the tile work up to 6-12 inches. The idea behind this lining system is that water that wicks through the grout joints on both the floor and walls is  pulled by gravity to the floor, then collects in the liner and drains through weep holes in the drain. This is the only place in the home where you find a drain hole so small. The problem with drain holes of this size is that they are easily plugged with sediment or worse, calcium.  After these holes become plugged the cement slab under the floor tile has no way of drying out. This is when we get the mold and mildew growing behind the tile especially in the corners. The first picture above shows a shower drain almost completely choked off with calcium growth. The second picture shows calcium deposits left behind in the stone's pores. The third picture shows calcium growing up from the ridge of the grout joint, and the forth picture shows the final stage where the bottom row of tile stays wet all the time due to the presence of water. At this point water starts running over the lowest part of the pan and rotting subfloor and floor joists. This can cause extensive damage to the home and after too long can result in having to change the entire shower.