Hello,
I moved into a new construction home at the end of May. The builder went into foreclosure after we fell in love with it so we don't have a home warranty through the builder or contact with the builder. It inspected just fine.

It is built with a crawlspace and the shower is on the first floor. We first noticed there was dripping in the crawl space so we called our home warranty company (that we purchased separately) and the plumber came out and cut the drywall next to the shower and found a nail through a pipe. He fixed that and the dripping seems to be gone. The drywall didn't seem to be affected by this leak.

While the next piece of information seems to be separate, I can't be sure. Next, the base of the wall near the molding between the shower and the sink counter appeared to be damp. This is at the corner of the shower. I cut a small portion of the drywall out and pulled the moulding off and it was wet with bit of mold. For the past week, we have not been using the shower to allow things to dry and prevent any further damage. The warranty doesn't cover damage so I think I have to do this myself.

Something I have noticed is that there is no caulk at the seam of the tile and fiberglass pan... just grout. This is my first experience with this so shoud I caulk this?

Thank you very much..

A properly constructed tiled shower will contain all water prior to a single tile going on the walls. Though the joint in question should have been caulked and not grouted, strictly for sanitary and aesthetic reasons, that alone should not be the cause of water getting behind the walls and replacing with caulk, if it does anything at all, would buy you only a very short amount of time before doing the entire surround over. From the hole you cut, can you see what was used as a backing? Is there anything there as either a moistrue barrier such as tar paper or plastic sheeting? Does the shower pan have a lip that sticks up behind the wall backing material? Any chance you could cut the hole a little larger, take some pictures and post them here?

Assuming that this wall is the wall that has the valve and shower head in it, pull the escutcheon ring around the shower arm away from the wall and look inside to see if there is any sign of water. Remove trim from around shower valve and look in there also.