24 year old tile over cement slab floor failing-tenting and popping up - Tile Advice

[TLovelace]

Hi, I've put down quite a bit of tile over the years but always worked with backerboard. I'm renovating a house in Florida (first one in Florida) that was built in 1996. It's concrete slab foundation and the tile was laid directly on the slab with what appears to be basic thinset.

When I was taking up old laminate, I cracked the seal on two tiles at the threshhold. I tucked that away in my mind as something I needed to address and kept working on other things. The other night I was awakened by a series of loud cracks. I discovered that a couple of the tiles near the two I'd disrupted were tented. Stepping on the tiles around them I could tell that a number of them had popped. The floor underneath looks normal, there doesn't seem to be moisture. If anything, it looks like the grout may not have been wet enough when the tiles were installed.

My plan is to remove the popped tiles, redguard the area and reset using thinset. But I'm concerned that it seems to be a regional failure in the field. I came here hoping to find someone with more experience with this substraight who might be able to advise me on what is going on. I am hoping that its just an area where the thinset was not wet enough and they didn't wet the back of the tile to help adhere them. There are a couple of other hollow sounding tile in the field, which is about 1000 sq ft total. I would prefer not to rip it all up right now unless there is a compelling reason. Appreciate your insight and help.

 

[Dave]

Tenting is a result of lateral stress. Strange to happen after such a long time.

 

[Ajax123]

was the house flooded in the last few rounds of storms and floods. that could set up a secondary expansion situation in the concrete or the adhesive which could lead to tenting. As Dave said its unusual after such a long time so either something has changed or its always been like that.

 

[TLovelace]

was the house flooded in the last few rounds of storms and floods. that could set up a secondary expansion situation in the concrete or the adhesive which could lead to tenting. As Dave said its unusual after such a long time so either something has changed or its always been like that.

No, as far as I know the house has not ever flooded. I read that expansion/contraction associated with temperature change can cause this. But, again, this house has surely experienced this many times in its 24 years. It's just odd.

 

[Ajax123]

No, as far as I know the house has not ever flooded. I read that expansion/contraction associated with temperature change can cause this. But, again, this house has surely experienced this many times in its 24 years. It's just odd.

Are the tiles new?

 

[TLovelace]

Are the tiles new?

No. The tiles were installed when the house was built in 1996.

 

[Ajax123]

So you need to figure out what has changed. As previously stated tenting is the result of lateral compression which occurs when the tile face and adhesive has insufficient room to expand usually, but not always, under thermal loading or during high temperature events. Other things that can cause it are secondary expansion or possibly shrinkage, or cracking and curling of the sub base and/or adhesive bed which should usually indicate contamination of some sort. If its all been stable for 24 years and this tenting is new it suggests some new phenomenon has occurred. It would be most unusual for this to have taken 24 years to manifest itself as its generally not a gradual process.

Until you can figure out what has changed you will struggle to sort it if fear.

 

[Ajax123]

Just to clarify, was the laminate over the tiles?

 

[TLovelace]

Just to clarify, was the laminate over the tiles?

The laminate was not over the tile. I've indicated in the attached photo where the two tiles were popped when removing the threshold in the room where the laminate was removed. It might be noteworthy to share that I've been renovating the house since October, for a week or so each month. In October I removed all the old laminate and underlayment from the rooms around this large room. There was moisture underneath the underlayment. There were a few hairline cracks in the floors. I sealed each of the floors with a concrete waterproofing sealer which was like rubber cement. I then put down a new underlayment and LVP. The damage to the tiles at the threshold did occur in October. So I did remove a source of moisture from the house in October and now the air has gotten drier (ish, it's Florida) and the heat was on a couple of days right before this happened. The week before this happened it had been pretty chilly, but it warmed back up. So maybe the temperature change, running the heat, and changing the humidity levels combined to a perfect storm? I would much prefer this to having to haul in a structural engineer and try to determine if the foundation is moving.

 

[Ajax123]

I very much doubt it's a structural issue. Youd see other issues to accompany it so I reckon you can put that out of your mind safely

Thermal shock due to the temperature change would probably do it especially if its underfloor heating. Specially if the heating was turned on at a high temperature relative to the ambient temperature of the slab. When turning on the heating aftercare cold spell its always a good idea to treat it as if it's the first time and turn it on slowly. Given there was some moisture that might also have played a part in that the adhesive or primer may have been weakened due to dampness. It's possible that there are not sufficient movement joints in the tile face

 

[TLovelace]

I very much doubt it's a structural issue. Youd see other issues to accompany it so I reckon you can put that out of your mind safely

Thermal shock due to the temperature change would probably do it especially if its underfloor heating. Specially if the heating was turned on at a high temperature relative to the ambient temperature of the slab. When turning on the heating aftercare cold spell its always a good idea to treat it as if it's the first time and turn it on slowly. Given there was some moisture that might also have played a part in that the adhesive or primer may have been weakened due to dampness. It's possible that there are not sufficient movement joints in the tile face

I should have been more specific, it is central heat, not under the tile. Florida is generally tropical. Climate change has caused some cooler temperatures that we usually see. I'm away for about a month, it will be interesting to see what changed in my absence. One other thing, the grout by and large was holding well. A few areas where it's crumbles at an intersection. Thank you for your input about the structural component. There are many things I'd rather deal with than that.

 

[Zack Mc]

TLovelace, what was the outcome of this? Did you find out what caused it? I have a similar issue with some tile on my house. No issues in 9 years then it started tenting is the middle of a large room.