Shower floor is 1 inch honed marble and walls are honed marble subway. Proper pan with an appropriate pre-slope and cement board walls all coated with multiple coats of liquid waterproofing membrane. Entire shower grouted and then sealed 7 days later by the homeowner. All changes of plane received siloconized caulking. After first use it was noted that certain tiles and grout lines were darker than others and stayed darker. An investigation revealed that on the vertical wall of the built in shower seat opposite the shower head (about 6 inches above the floor) there was a one inch gap in the grout line.

The supposition is that water makes it's way in there and then flows down in a sort of meandering line under the tiles and to the drain soaking the grout and tiles along the way from underneath. Careful inspection revealed no other gaps in grout or caulk lines. It is also possible that the homeowner missed some small areas with the sealer.

After 7 days of no usage with a high powered fan moving air across the tile there is little change. The missing grout is not yet repaired and the shower has not been resealed in the hopes that the moisture will work it's way up and out.

Is there anything further that can be done to speed the process? Perhaps a dehumidifier in the shower?

  • It may help clarify things: Are you the homeowner attempting to do these repairs yourself? Are you the builder called back by the homeowner attempting to do right and stand behind your work, but at a minimum cost/fuss? (Nothing wrong with either, but knowing may help guide the answers.)
    – FreeMan
    Nov 7, 2020 at 15:08
  • Over time the water may evaporate but it may take a very long time. If the area was sealed well except for the small opening in the grout, then a relatively large amount of water could easily have entered. But once it the only way out of through the same crack and that's a really small opening. If there is any way to apply heat that would help speed the process but it still may take weeks for it to dry enough to safely seal it up. Best case is to remove the tile, dry or replace the wet materials, and replace the tile.
    – jwh20
    Nov 7, 2020 at 19:08
  • @FreeMan I did the install from studs to grout. Homeowner did the sealing of the grout. Nov 7, 2020 at 19:35
  • @jwh20 It's possible the homeowner missed a section of grout with the sealer about a foot long. I say this because it is the only grout on the floor that is noticeably darker than the rest and it wasn't that way before use. Maybe a dehumidifier would add a little heat as well if we close the shower door? Nov 7, 2020 at 19:38
  • Heat. Air movement is not really possible so heat would be the next best thing to facilitate evaporation. How to get heat directed to do the most good is the key.
    – Alaska Man
    Nov 7, 2020 at 20:08


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