What is causing my Ceramic Tile to Buckle / Tent up?

QUESTION

My condo was built 11 yrs. ago. I’m the original homeowner. The ceramic tile in my kitchen & connecting sunroom is “tenting” and the buckling /tenting is spreading. The tile floor is over a floating concrete slab. Up to 6 professionals visited/inspected only to remark they’ve never seen anything like ceramic tile buckle. I personally learned the term tenting via google. Everyone is eager to get hired to rip up and install a new floor. However, I cannot afford to put a band-aid over the problem which can reoccur. I need someone’s help to figure out the real source of the problem. I feel the problem is related to a moisture issue, but how do I determine the source? My new exterminator said every bug I’m having a problem with likes moisture I.e.: earwigs, centipedes, silverfish, spiders, etc. I don’t know who to trust or what to do next to correct this frustrating problem. Please help!

ANSWER

ANSWER - When tile debonds and buckles up we do refer to that as tile tenting.  The cause of tile tenting is normally due to several compounding conditions.  First is that normally the tile installation does not have any movement joints, or not enough movement joints, to allow the tile to expand.  There should be perimeter movement joints at the walls and other restraining surfaces, and at least every 25 feet for interior applications.

If the ceramic tile has a porous clay body, then it is more susceptible to moisture or high temperatures causing the tile to expand.  If there are no movement joints when the tile expands then it is constrained and the tile is subjected to an upward force that can cause it to debond.  Once the tile debonds it relieves the stress in the tile that results in the tile tenting up.  If the tile isn't bonded very well to the substrate, then it will have a greater propensity to tent up since it can't resist the stress as well as a well bonded tile.

Not sure what you mean by a floating concrete slab.  Perhaps that there are no footings to the concrete slab, which doesn't seem reasonable.  Or maybe you mean there is a cementitious mortar bed over a wood subfloor?

If the concrete slab is installed over a ground without a vapor retarder that keeps the water from the ground from migrating up through the slab, then that might be the source of the water.   So high moisture with a non-vitreous porous tile means the tile will expand.  If there are not any movement joints and if the tile isn't bonded well then you will likely get tile tenting.

You could try repairing it by removing the tented tiles and letting it dry out to see if they will fit back in.  Then cut in movement joints at the perimeters.  More than likely you need to replace the tile floor, but with the new installation install a moisture barrier over the concrete slab and then adhere the tile to it.  Plus install the movement joints.  If you replace the tile with a porcelain tile that is impervious then it won't be as susceptible to expansion from moisture.

12 thoughts on “What is causing my Ceramic Tile to Buckle / Tent up?

  1. DBArchitect says:

    A floating slab means a standard thickness concrete floor slab on grade, but separated from the perimeter foundation walls by a continuous joint – so that the slab can “float” and settle/move independently in relation to the foundation. Typical in commercial construction, not so much in residential construction – but certainly possible especially in condo and apartment buildings.

    • Donato Pompo says:

      Thank you for the clarification DBArchitect. So this would also apply to a slab on grade/ground that does not have a perimeter foundation wall as you may see on residential patios. It would not apply to a concrete slabs using steel piles for the foundation due to unstable soil conditions as it would restrict the slab from moving.

  2. Mark Lansman says:

    We have had a similar experience. 13 year old FL home built on a concrete slab. We have experienced unusual rainfall in the weeks preceding the “tenting”. No movement joints and we have tile throughout so many spans are greater than 25’. Some have pointed at thermal (i e CTE mismatch) issues but nothing has changed in that respect.

  3. Donato Pompo says:

    Normally when a tile tents it is due to expansion of the tile where there are no movement joints to mitigate the stress and strain (movement) and that the tile may not be bonded as well as it could. The lower the bond strength the sooner the tile releases.

    Tile expansion can be caused from thermal movement, but in your case it seems that the tile was subjected to excessive moisture. If the tile is a more porous tile then it would tend to expand more than a more dense tile that doesn’t absorb as much.

    In some cases you might be able to just repair the loose tiles and cut in some movement joints; particularly at the perimeters where they abut restraining surfaces.

  4. Kevin Genaw says:

    I have just recently had tile tenting in a hallway 3 foot wide and thought it was from an adjacent ac drain that may have been clogged. Causing moisture under tile. But tile and slab were dry. Tile is 30+ years old. Would it be normal to have this occur after that many years? Not sure how to tell if I have perimeter movement joints. Is it just an amount of space from the tile edge to the wall? Ac guy never saw this tenting before.

    • Donato Pompo says:

      Tenting of tile is normally due to the tile expanding, when the tile is constrained. So as it expands it goes into compression and then there is a tensile force pushing up.

      Movement joints are suppose to be at the perimeter of the wall such that there is either about a 1/4″ wide gap without any grout or anything in it causing the tile to be constrained. You can leave it open and cover it with a tile or wood base. Or if you don’t have a base or you didn’t remove the base when you installed the tile, then there should be a 1/4″ wide gap that you fill with an ASTM C920 sealant that will allow the tile to expand without constraining it. There should be either a closed cell foam in that movement joint leaving at least 1/4″ depth for the sealant. If you don’t have room you can install a bond breaker tape or put sand in the joint leaving space for the sealant.

      You are also suppose to have movement joints throughout the tile installation at least every 20 to 25 feet and when subjected to direct sunlight every 8 to 12 feet in each direction.

      When tiles tent, it could be due to a combination of not having movement joints and the thinset mortar adhesive not bonding as well as it should, so it can’t resist the stress caused by the lack of movement joints.

  5. Makarios Rolle says:

    I laid tiles in bedroom where previously had carpet then faux wood flooring. Within a few months the tiles in the middle of floor darkened one by one. After a further few months the tenting started. Affected area was more or less the central area of room. After taking up tiles, excessive water was found and also tiles were installed butted hard against walls all around. No water line runs under this slab area and adjourning room which was tiled at same time has no issues.

    • Donato Pompo says:

      I am assuming you installed a ceramic tile over the floor that had carpet and then probably a laminate wood floor.

      When tiles tent or buckle it is normally due to a combination of deficiencies. The tiles should not have been constrained by being butted to the wall. The water/moisture will cause the tile to expand to some degree. If the tile expands and is constrained then it puts into compression and the only way out is up. If the substrate wasn’t properly cleaned and prepared before the tile was installed then the tile’s ability to resist the stress is less and makes the tile more likely to tent up. Question you need to answer is where did the water/moisture come from. You need to find the source and divert it.

  6. Kinjal says:

    Can Tile Tenting take place when a abnormal load is placed on the tiles. I have 20msq surface under tiles, part of the floor 3.5msq is covered by a plastic pool, calculated weight 3.5 tons. Now I have popping up/tenting on the opposite side of the room. What is your understanding with the abnormal load.

    • Donato Pompo says:

      I have never seen a correlation between a floor being subjected to a heavy load that then results in tiles tenting up.

      That said, hypothetically the heavy load could constrain those tiles that it sits on that in effect could put the adjacent areas in greater tension over a shorter span because they can’t full distribute the stress they are subjected to from other sources.

      I doubt this could be the cause of the tenting tile, unless the tiles were not bonded very well and had a lower threshold to resisting normal stresses.

  7. Ed says:

    My 60cm x 60cm ceramic floor tiles in my 30th floor condo unit recently tented and buckled. I tried having the originally 4 pieces of tented tiles repaired. But when the repairmen started to remove the tiles, it created a domino effect and all the remaining tiles started buckling and lifting. Reading from other similar stories above, when my tiles were installed, the installers did not provide perimeter gaps. Does it matter that my condo unit is on the 30th floor and is located in an earthquake-prone city?
    Anyway, I am not using ceramic tiles anymore. I will switch to laminated wood planks.

    • Donato Pompo says:

      Normally when there is a failure like that it isn’t due to only one deficiency, but rather due to multiple compounding deficiencies.

      Yes per industry standards they should have had perimeter movement joints and movement joints every 20 to 25 within the field of tile and every 8 to 12 feet in each direction if the tile is subject direct sunlight from windows.

      Chances are that they also did not adequate bond the tile to the substrate for various possible reasons.

      Tile is installed on high rise buildings all the time. If the tile had been installed correctly then there is no reason why it would fail and it should last the life of the building. Sorry you had a bad experience and you did not get all the benefits of tile.

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