Can moisture in a Concrete Floor cause the Thin-set Adhesive to Deteriorate and result in Hollow and Tented Tiles?


If moisture leaches up from the concrete floor of a ground floor condo could it cause the thinset to deteriorate? Resulting in hollow sounding tile and some of the tiles tenting up?


ANSWER - Thin-set mortars should not deteriorate from being exposed to moisture.  Most thin-set mortars are used in showers and in pools and fountains.

Moisture that migrates into the concrete slab from the ground and into the tile can cause tiles to expand; particularly if the tile is very porous.  If there are no movement joints filled with an ASTM C920 sealant at the perimeters or every 20 to 25 feet in interior areas not subjected to sunlight or every 8 to 12 feet if subjected to interior direct sunlight then those conditions can lead to the tile debonding, sounding hollow, and tenting.

4 thoughts on “Can moisture in a Concrete Floor cause the Thin-set Adhesive to Deteriorate and result in Hollow and Tented Tiles?

  1. Ramona Neal says:

    We need help in Florida. Our tile is tenting and the grout is cracking. Hollow tiles throughout 90% of the house. We cannot get the builder to do anything. Our house is only 6 1/2 years old.

    • Donato Pompo says:

      If there was a flood or an extreme heat of cold event then you could file a complaint with your insurance company if there is evidence it was resultant damages from the event. If it is pre-existing damage then it would not be covered.

      Tile should last for decades if not longer if installed correctly. It is clear that your tile wasn’t installed correctly If the builder has a limited warranty he may or may not be responsible for the repairs. You could file a complaint with the contractor’s board to see if the building would respond to that pressure.

  2. Pam says:

    Should Schluter or Redguard be put down first if moisture can be visually seen in areas of the concrete? We are having porcelain tile laid on 80 year old concrete that is very level and only one crack at the center of the house. The crack did not really affect the levelness and the rest of the house is very level. Location is eastern NC where temperatures don’t tend to be extreme, but humidity is always present (not sure if that is relevant or not).

    • Donato Pompo says:

      If you can see moisture coming through the concrete that might suggest that you have a hydrostatic moisture problem. That means water from a higher elevation is traveling down to your concrete slab area. This could also be a case where you have a high water table and water rises and drops depending on how much rain you get. If it is hydrostatic then there is a pressure pushing the water up and that can be a problem for any type of floor covering even with a waterproof membrane over the slab.

      If you do have a hydrostatic water condition then you need to mitigate that by installing trench drains around the perimeter outside of your house to divert the water.

      If you do not have a hydrostatic water problem, and you only have a high moisture content in the concrete slab from water migrating to your slab, then you need to install an epoxy vapor barrier system. Custom Building Products, Laticrete and Mapei and others have these products where you can adhere your tile to them.

      If you don’t have an excessive moisture issue then Redgard or Schluter crack isolation membranes would act as a moisture barrier too. Make sure that the crack is not a structural crack, as the crack isolation membranes only mitigate shrinkage cracks. If there is lippage on the crack where one side of the crack is higher or lower than the other, then that is a structural crack and has to be repair first.

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