Expert: Torin Dixon - 2/4/2008

Question
QUESTION: This summer I had a travertine shower installed where a soaking tub had been originally.  The shower is beautiful--contracter did a good job of laying the tile.  However, after using shower a few months, I noted a darkened, irregular stain along the walls where they meet the floor.It looked like water had been sucked up irregularly by the wall tiles.  All tiles had been sealed, including the grout between walls and floor.  The tile company told me that all 90 degree angles should also have been caulked, using same color as grout.  The contracter is willing to come back and caulk if I want him to, but he says he never heard of the necessity to do that.  What do you think?  (I spent 10K to have the shower built, and now am hesitant to use it!!

ANSWER: Marilyn,
Sorry for the delay. I have been out sick.
The "stain" sounds like moisture. What method was used for prep? Cement board for walls, or Mud-set? In either case, the moisture is certainly wicking up into the tiles. Was a quality sealer used? Is the shower draining quickly, or is there standing water in the bottom when shower is turned on? I suggest allowing travertine to completely dry out, then use HMK S34 Silicone Impregnating sealer to seal the tiles and the grout. On travertine i suggest at least 2 coats. You can order HMK products from
http://www.stonecareonline.org
Another thought, if you have a mud-set job, the moisture may be wicking up into the wall mortar. This indicates a problem with the drainage. Did the contractor clear the "weep-holes" in the drain. If not, the mortar in the pan will become saturated and the moisture will wick up the walls.
Hope this helps,
Tad Dixon
406-360-1684


---------- FOLLOW-UP ----------

QUESTION: Dear Tad,
I will check with the contractor regarding your comments. In the meantime, I have been allowing the shower to dry out and have used a "poultice" of hydrogen peroxide-soaked paper towels covered with plastic wrap for several days, and then allowed to dry out.  It has been quite effective in removing the water marks, but I still must decide if it will be necessary to caulk the 90 degree seams.  A good, expensive sealer was used, and the tiles still "bead up", so I don't think it needs to be re-sealed. Have you ever seen a professionally installed travertine shower that has the 90 degrees caulked in addition to the sealed grout?

Answer
Dear Marilyn,
The only time that caulking the vertical joints is usually necessary, is when the underlayment is a cement board(Wonder Board) or Hardibacker. These materials are easy to install, but remain a bit flexible. This can lead to cracking of the grout joints in the corners, thus allowing water infiltration. The best (and more expensive)method of installation is the  Mud-Set application.
I suspect the positive results you are seeing with the hydrogen peroxide, is simply the result of the water evaporating out of the stone.
When wet, all natural stones turn darker.

By the way, what you describe as a "poultice" is really not a professional poultice. If you mixed the Hydrogen Peroxide with casting plaster (plaster of paris) and covered an organic stain with the mixture and covered it with plastic, the chemical reaction would create significant heat as the plaster set up, drawing the stain out of the stone into the poultice. This is not recommended for your situation.
Your description indicates saturation and moisture migration (wicking up the walls).
Best,
Tad