We did a bathroom remodel which included new tile in the shower. Walls and floor. We have run a bead of caulking where the shower wall meets the floor.

The caulking appears to dry at first but after a few days it forms bubbles in places and begins to break down. It never really drys.

We have replaced the caulking several times all with the same result.

We have talked with the tile store and then with the manufacturer of the caulking. The caulking manufacturer told us the problem is that the mortar behind the tile on the walls has never completely dried. Therefore there is moisture behind the walls. The moisture is preventing the caulking from drying.

It has been 18 months since the remodel. 2 months ago we removed the caulking and decided to let the shower sit unused and un-caulked to allow the tile mortar to completely dry. To test it we have stuffed some tissue in the crack where the wall meets the floor. We leave it there for a day or so and pull it out. It does come out with some some moisture on it. Not soaked by any means but some moisture.

Does anyone have any ideas how we resolve this problem? Have you ever heard of this happening? How can it possibly take this long to dry? It has been 18 months.