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


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 - 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.

24 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.

  8. Jennifer S. says:

    Can tile laid on a poorly manufactured prestressed concrete slab floor pop up? We’re considering buying a house and they had problems with popping tiles and repaired the area where the popping occurred. However a large area otherwise is unaffected. They were told it was bad substrate bonding not moisture. Tile seems to have popped a while after installation based on grout wear and tear. Not in direct sunlight. Expansion joints, if present, covered by baseboard. Is 40+ yrs old house built on soil with high clay content. Thanks

    • Donato Pompo says:

      Chances are the tile tented up due to the improper tile installation and not the concrete slab itself. If the concrete has structural cracks then they need to be repaired. If it simply has shrinkage cracks you can mitigate that with a crack isolation membrane during the tile installation. There are uncoupling membranes that can be installed over a concrete slab that has a lot of shrinkage cracks or if there is suspected movements. The uncoupling membrane is installed over the concrete and the tile bonded to it. You still need movement joints at the perimeters of the rooms and every 20 to 25 feet within the field of tile. Areas with direct sunlight have to have movement joints every 8 to 12 feet in each direction.

  9. Sherry Ferguson says:

    I am having the same issue in my 2 year old house. It is happening in my kitchen and in a hallway on the other side of the entry way. The tenting or bubble is getting bigger and wider. The builder sent their engineer out who said nothing is wrong with the foundation, it’s a workmanship issue. I’ve never seen this before in such a new house. Any ideas or suggestions?

    • Sherry Ferguson says:

      Let me add, the builder said that here in the state of Texas they don’t use joints they use zippers – a separation in the concrete when poured

      • Donato Pompo says:

        Sounds like an excuse by the builder. That likely has nothing to do with the tile tenting problem. There are standards for putting control joints in the concrete slabs. Those joints have to be honored by the tile assembly being installed over the slab. In addition to that, the tile industry standards require additional movement joints in the tile assembly. Particularly at the perimeter of the rooms at constraining surfaces, at transitions of plane, and at transitions of materials.

    • Donato Pompo says:

      Tile tenting is a problem that can arise from the lack of movement joints at the perimeters and within the field of tile, and there could be other contributing deficiencies. Industry standards say they should be installed. If the builder says it is a tile workmanship issue, then he should get is tile subcontractor to fix it or to pay to have someone else fix it.

  10. Sam Updike says:

    Can shrinkage of the substrate concrete slab cause tenting of the tile? My plans call for control joints to address shrinkage in the slab, but apparently they were left out

    • Donato Pompo says:

      Yes, shrinkage in the substrate can cause tiles to tent. We have had cases where this has occurred. A way to verify this is to remove the tented tiles and see if they can fit back into the space they were originally installed in. If the space is smaller then that would suggest that the substrate shrunk.

  11. Jorge says:

    My dallas texas home is 21 yrs old and tiles started to tent and crack , noticed some light tenting last year now is buckled up .. we have tile floor almost on all open spaces , we also have engineered wood floor and that has not buckled.. so after 20 + yrs tile decided to buckle !!!—- what’s weird is wood flooring has not had any damage so I’m thinking is moisture as we have had rain for days straight lately….plus wife has been cooking alot generating (steam) windows to fog up , which kitchen tiles happen to be the ones cracking …,

    • Donato Pompo says:

      Normally when ceramic tiles tent it isn’t due to a sudden event, but rather due to years of the tile floor going through cycles of expansion and contraction when there are no resilient movement joints to mitigate the stress.

      Porous tiles are more susceptible to this situation because they can absorb more moisture that causes them to expand more. If the tile is constrained at the perimeters and there are not resilient movement joints to mitigate the stress, then at some point the stress exceeds tile bond to the substrate’s ability to restrain the tile from moving. When this happens often you will hear a release noise as the tile buckles up.

      In some cases it might be possible to repair the tile floor by replacing the tiles and adding movement joints, but in some cases it is more practical to replace the floor.

      A movement joint is a joint between tiles that is either fully open unconstrained or it is filled with a resilient ASTM C920 sealant over a foam backer rod or bond breaker tape. It is normally a traffic grade silicone or polyurethane sealant.

  12. Cecilia says:

    I am hoping this is the right place to ask an expert’s opinion about my issue. I have had Terrazzo flooring for about 40 years and decided to put vinyl waterproof plank flooring on top. Before placing this new flooring, the wide grout lines needed to be filled in with some type of mortar or concrete. Everything was great except, after 7 months, the vinyl plank started bulging in one area. Upon removal of the planks to look underneath, we realized the Terrazzo flooring had bulged up in that small area. The installers are blaming it on moisture from underneath the original flooring, but we’ve had it for about 40 years with no issues (even withstanding floods from hurricanes). They are not taking any responsibility for the installation of the vinyl being the problem. From everything we read, including the tile manufacturer’s instructions, there should have been no issues with placing them on top of this existing tile, including filling in the grout lines. Still, do you think that having filled them in is the problem because now the Terrazzo tiles cannot expand? What else do you think could’ve caused this and am I risk of it happening all over my house? Thank you.

    • Donato Pompo says:

      When vinyl products tent up normally it is due to them being subjected to excessive moisture. But since you said that it was the underlying terrazzo tiles that bulged up, then that is likely what caused the vinyl to bulge up, but moisture could have been a contributing factor.

      Once you do put the vinyl over the terrazzo tile it caps the terrazzo off, so if there was high vapor passing through the terrazzo before, then capping it off would have caused the terrazzo tiles to retain moisture. In theory, the terrazzo could expand from absorbing moisture. If the underlying terrazzo did not have movement joints installed at the perimeter walls or every 20 to 25 feet in each direction within the floor area, then that could have caused the terrazzo tile tent up (bulge). It might not have been a problem before because of the wide porous grout joints allowed the moisture to pass through and evaporate so the terrazzo didn’t retain moisture to the degree that it caused it to expand.

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