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Can moisture in a Concrete Floor cause the Thin-set Adhesive to Deteriorate and result in Hollow and Tented Tiles?
QUESTION
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
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.
6 thoughts on “Can moisture in a Concrete Floor cause the Thin-set Adhesive to Deteriorate and result in Hollow and Tented Tiles?”
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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.
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.
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).
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.
Hello,
We recently had an addition put on our kitchen The existing floors are very uneven and our contractor suggested laying a mud sub floor over it (sand & concrete mix over mesh) Our tiles are 1/2” handmade ceramic cotto tiles from Zia tile. They suggest to let a new subfloor cure for 30 days before laying tile. Is this true with a mud floor or can we wait two weeks and be ok? Thank you so much for any advice!
First of all beware of Zia types of hand molded tiles. Although they may have a very desirable look from a selection point of view, they are very irregular in their various dimensions and will have warpage tolerances in excess of the industry standards. The tile industry has formed a committee on this type of hand molded product because people tend to get false expectations on how it will look installed. This can result in unhappy customers and unhappy installers. So make sure you don’t have false expectations. Hand molded tiles have been around forever and give a very desirable appearance if you like that irregular look. But you will get more tile lippage and irregular grout joints to some degree.
Regarding mortar beds (mud as some say) normally a deck mud/dry-pack mortar can be installed the same day or the next or beyond. This mortar (sand/cement and sometimes with lime) is normally not a wet mortar mix and you don’t add a lot of water. It looks like damp sand. You should be able to compact the mortar to make it stronger. You should be able to squeeze it into a ball and it stays together or you haven’t added enough water.
For poured concrete floors, they do say you should wait 28 days under certain temperatures and humidity so it can cure and shrink without affecting the tile installation. Some polymer/latex modified thinset mortars will allow to bond over 14 day concrete. But it also depends on on thick is the concrete, what is the underlying substrate, and what is the temperature and humidity.