Ceramic Tile tenting

[Kimber]

My tile floor was installed 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 15 tiles 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?

 

[Dave]

I very much doubt it is the drum kit. Tenting tends to be lateral stress, a number of issues can cause this from from too large an area tiled without expansion joint or even the lack of perimeter joints.
An expansion joint within the tiling field will have a rubber insert to allow movement.
what type of substrate is under your tiles. ?
And can you post sone pictures of the issue.

 

[Tony_C]

Definitely not the drum kit as Dave has already said

 

[Kimber]

Thank you so much for your input. I attached 3 photos, if you look close I put a black X on the tiles that are hollow there are many. Pretty much all the tiles in the wide-angle pix. The substrate under the tiles I believe is a concrete slab.

 

[Dave]

Thank you so much for your input. I attached 3 photos, if you look close I put a black X on the tiles that are hollow there are many. Pretty much all the tiles in the wide-angle pix. The substrate under the tiles I believe is a concrete slab.

How tight are the tiles to the outer walls. Tenting usually occurs due to lack of expansion, either way it looks like a re-tile is required

 

[Kimber]

I took a picture with a ruler. One is the outside wall south facing and the other with the removed tile is the west outside wall.

How can I tell if they used the rubber inserts for movement?