What caused the Tile Floor to Tent up / Debond?

QUESTION

Hi, I was just at my friend's home to look at her "tenting" tiles...
Tile was installed ~20 yrs ago.
For YEARS she's had a fish tank on the floor (w/stand) that weighed almost 1/2 ton.
3 weeks ago she sold it.
Soon after that the ~15" square tile IN FRONT of where the fish tank was started tenting & cracking.
I removed some of the tile & the floor under the tile was smooth, level, *very* solid & completely dry.
Could the foundation under the fish tank have cracked, and then removal of the tank caused the crack to expand (causing the tenting in front of where the tank was)? Or does anyone have any other ideas?
PS: The area of tenting/cracking is slowly expanding.

Thank you very much!

ANSWER

ANSWER - Tiles tent for several compounding reasons.

Lack of Movement Joints (also known as expansion joints) - When tiles absorb moisture or gain temperature they expand.  The more porous the tile the more it will tend to expand under those conditions.  Movement joints are installed every 8' to 25' in each direction in the field of tile, and at perimeters or restraining surfaces that the tile abuts.  In lieu of filling these grout joints with a cementitious grout, they are filled with a resilient sealant (caulking) that meets ASTM C920 standard.  Typically that is a silicone or urethane sealant.  The resilient joints mitigate the stress that the tile is subjected to from expansion.  If you don't have movement joints then tile is under compression stress.

Lack of Tile Adhesive Bond Strength - Depending on what substrate the tile is bonded to, and how well it is bonded to it, the tile may be restrained to some degree from expanding.  If the stress the tile is subjected to is greater than the tile adhesive bond strength, then the tile will debond and tent if there are no movement joints to mitigate the stress.

Substrate is Resilient - If the tile is bonded to a resilient substrate, such as a crack isolation membrane versus a non-resilient concrete substrate, then when the tile expands it can only limitedly restrain the tile.  In other words, it will allow the tile to move to some degree, which could be problematic.

Chances are that the referenced tile installation did not have movement joints and over the years was subjected to expansion/stress for one reason or the other.  So the tile had pent-up stress and was being held down by the heavy fish tank.  When the heavy fish tank was removed the tile bond was not great enough to restrain the tile, so the tile tented-up, which caused the cracking.  It is not unusual for the tenting to expand if you do not relieve the stress in some way such as removing the tented tiles.  If other tiles adjacent to the tented tiles sound hollow, it might be an indication they too have lost their bond.

The only thing to do is remove the loose tiles, install movement joints, and re-install the tiles and hope that the damage is limited.

4 thoughts on “What caused the Tile Floor to Tent up / Debond?

  1. Kim says:

    My tile floor was intalled with the add on room about 15 years ago. Several years ago I noticed a few tiles in this south/west corner sounding hollow, but all the grout was good.
    10 months ago, I set up my electric drum set in this area. Off and on at times, I would hear a popping sound while I was watching TV in this same room. I thought it was the house settling. Then recently it became more frequent. I walked over 10 to 15l tile in this corner and hear crunching. As I was playing the drums I felt the floor shift and the tiles tented, about four tiles at the tenting.
    I’ve read your answers about placing movement joints, not sure they were placed, what do they look like? We have earthquakes in So. California. I wonder if the vibration from the drum kit would cause this? The drums are held by a four-legged frame and they are not loud like a regular drum set. Still could this be my problem?

    • Donato Pompo says:

      The drum playing could have been the straw that broke the camel’s back as they say. The drum playing did not cause the underlying problem. Generally speaking when you get tented tiles it is because of several compounding deficiencies. The tile may have not been properly bonded in the first place. If the tiles are butted to the walls and counters and there are no movement joints (grout joints field with a special caulking meeting ASTM C920), and if the tiles were subjected to moisture or high temperatures they would expand causing compression the tensile stress that put the tile under tension. At some point if the stress becomes greater than the bond strength of the tile, the tile releases and tents. The drum vibration may have added that additional stress that triggered the tile tenting.

  2. Donato Pompo says:

    Question from another party: Hi…my father has 2000 sq ft of 24 year old tile in his Palm Desert home. He is 88 and now had a section buckle up last night right in the middle of the family room. He has determined that other tiles here and there in the house have been hollow for years but now cracks or stress. But now he is faced with getting this buckled section fixed. Do you have any recommendations on ‘tile fixers’ in the Coachella Valley that you can recommend and follow your standards or have taken your trainings? Thanks so much in advance.

    • Donato Pompo says:

      You might have problems finding someone qualified and willing to only do a repair. Good installers are busy these days and they don’t want to inherit someone else’s problem. They would be more willing to do a full replacement as there are likely multiple underlying issues.

      CTaSC gets involved in specifying and overseeing the work, but it isn’t practical for hiring a company like CTaSC on smaller projects with smaller budgets.

      Replacing the tented tile (the symptom of a problem) won’t prevent future performance unless you identify the cause and remediate the underlying problems and not just fix the symptom.

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