We cannot find the source of the water damage to the hardwood floors in our master bedroom. The area of damage is right outside the master bathroom. The closest fixture to the damage is the standing shower with glass door but we can't figure out exactly how it's happening. We can't see, feel or hear a leak and the only evidence of water damage is the cupping of the floor outside the bathroom door.

Timeline:

* One month ago, I had a company come out to recaulk the shower and seal the grout as part of general preventative maintenance. He removed the existing acrylic caulk and replaced it with a more flexible caulk that will last longer. The tile is marble.

* Last weekend, we found significant cupping in the area where the hardwood floors (red oak) meet the bathroom tile (marble). The affected area is roughly 7 feet wide and 2.5 feet deep.

* We have not used the shower for three days and the damage does not appear to be getting worse, but the floors have not yet started to rebound.

* We do not see or feel any water damage to the walls or ceiling in the master bedroom or master bath or anywhere else in the house, including below the affected flooring.

Attempts to find the source:

* A hardwood floor expert said that the damage was definitely water related and it would have to be a constant source of water, not condensation or a spill that was cleaned up right away. The deepest cupping appears to be in the plank that is right next to the right side of the door jamb, which is about a foot away from the shower. The cupping radiates out from that deepest point, improving as you get further from either side of the right door jamb.

* A restoration expert used an infrared camera to look for leak sources in the wall behind the shower and in the ceiling below the shower and did not find anything. The baseboards and door jambs are completely dry and dusty. The baseboards are flush with the wall and don't appear to be pulling away. However, the expert's moisture reader went off the charts when he put it on the flooring.

* A plumber looked at the recent grout/caulk work and said it looks fine. He pointed out that there was an area at the bottom of the glass shower door where the plastic edging was bent and coming off so the door probably needs a slight realignment and weather stripping. It's possible that some water is splashing through there but a test of someone using the shower showed that the other side of the door facing the wood floor remains dry.

Next steps:
We are now going to spend significant $ on special heat blankets and dehumidifiers to dry out the floor for a week. It's possible the flooring will return to normal (or 90% normal) without refinishing and repair. But we can't find the source of the water damage and that worries us. We welcome any ideas for what else might be going on. Thank you!