I have a relatively large tile shower that is leaking very slightly onto the ceiling of the room directly beneath it. My question to the experts is this : "Do all showers (including custom) have a "shower pan" (not sure that is the correct name)?" The reason I am asking is that I have not been thinking that the leak is around the base of the wall where the tiles meet the floor. The reason I was not thinking this is due to the fact that I assumed there was a shower pan and therefore the water could not escape. Is this the case? Should I apply clear silicone over the grout around the base of the shower? Any help will be appreciated greatly. Thanks.