It almost sounds like they may have not installed a P-trap to your shower. Although I don't know how they would have neglected to do this is the smell a sulfur like smell?
Hi,
I had a new bathroom finished in early 2008. This spring I started getting a musty smell from the shower stall. I cleaned it thouroughly and stopped using it for a few weeks to see if the smell would go away but no luck. I have a second bath in another part of the house which has never had any such problem.
The only other curious thing that happened in relation to this bathroom was over the winter. Occasionally, when I flushed the toilet and ran the water in the sink I would get a loud banging sound. It would only last a few seconds and didn't have any obvious effect on either the flushing or the water pressure.
My house is on the market so the timing could not have been worse. Any help/suggestions would be greatly appreciated.
Thanks