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Question

We have an outside porch off the kitchen. It is have covered with ceramic tiles. There is (rubber?) membrane covering the wooden layer underneath. AN exterior / interior thinset was used to fasten the tile to the membrane. The tile store said there should be "mud set" over the membrane but I do not know if that is true. Monday I will talk to the man who installed it and is repairing it. He does not seem to know why we have the problem - efforescence is what the tile company called it, ie a liquid, probably rain or cleaning water coming up along the edges of the tiles which evaporates and leaves a white film/deposit.

How can we stop this from happening and what do you think that is the cause? Water is obviously getting down to the adhesive because of cracks between the grout and the tile.

Submitted: 120 days and 8 hours ago.

Category: Home Improvement

Value: $15

Status: CLOSED

Posted by Rick 120 days and 7 hours ago.

Answer

Hi XXXXXXX
I would have to agree with the tile store that, in this application the tile should be mud set. The problem is that water is seeping into the grout and getting to the thinset possibly breaking the bond with the membrane. You didn't mention if the porch floor is exposed to the elements. If it is then there may be flashing issues.
If the tile had been set in a bed of mortar the mortar bed has it's own integrity. It is not dependant on the bond to the membrane.
I can't suggest a solution without much more detail; open to the weather? inside a weather tight room? open but with a roof over it?

120 days and 7 hours ago.

Reply

I tis an outside porch. The liquid comes out especially when the full sun hits it for awhile so as to heat up the tile and I suppose the region underneath. It seems to me that the color of the oozing liquid - white - should be a clue of the source of the material that is dissolving in the water. Why would the adhesive dissolve in water if is made for outside use?

Accepted Answer

The adhesive isn't dissolving. The bond between the membrane and the thinset is probably breaking down. The thinset is still there it just isn't stuck to the membrane anymore. Water is getting in under the tile as the thinset (which is basically portland cement) absorbs it. When it dries out anything dissolved in the water will precipitate out. This is the efflourescence you see. I'm sorry but I don't see a permanent solution short of tearing it out and doing the job properly which would mean setting the tile in a mortar bed and flashing it properly.

Accepts:
Expert:	Rick
Pos. Feedback:	100.0 %
Answered:	7/25/2009

General C&ontractor

Licensed Construction Supervisor & Remodeling Contractor 35+ years experience

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