Question:
My garage was tiled with 16" tiles by the previous owner.
I noticed today when I step on the tiles in the middle of the garage, it
is bouncy. Concerned, I removed the grout around one of the tiles, and
noticed there is about a 1/2" void space below that tile.
The house is a single story monolithic slab resting on piles, no crawl
space, soil is sandy. Located in Miami Florida. The main house has an
8" slab and the garage has a separate 4" slab. The garage elevation is
about 8" below the main house. The previous owner leveled the garage
floor, and poured additional concrete so they are only about 3"
difference in elevation. On top of the concrete floor he tiled the
garage floor with 16" tiles. So there is no wood subfloor at all.
We lived in this house now for five years without any problems with
these tiles. Why would they suddenly pop up now? It is strange that
even with about a half inch void space below the tiles, and I bounce up
and down, the held together without any grout cracks. I can see the
floor where is buldges in the middle.
My question is, what is the cause of this? Could this be a sign that
the garage slab is settling (all of a sudden), causing the tiles to pop
up, or is it just the tiles themselves? When I removed that tiles, I
put my hand on the slab below after I removed all the loose thinset, the
concrete slab felt dry, I do not felt any moisture.
One thing that seems a little strange, when I was removing the grout in
order to pop up one tile in the middle, I got it to a point that most of
the grout are removed, but the tile still stayed together, so I hammer a
screwdriver in several places to break it open. As soon as it broke
open, I felt a small draft coming out. This is a tiled floor resting on
8 inches of concrete, why would there be a small draft coming from below
the tiles?
There is no noticable movement in other part of the house (which are
also tiled).
Now on to the question:
how do I tell if the tile is coming up or the floor going down. I am
especially concern with things like sink holes. What if the underground
water or sewer pipes are leaking and is washing about sandy soil,
causing a void below to cause this? All utilities are underground
including electric, water, sewer, phones and cables.
If it is just the tiles poping up, I am seeing may be about 30-40 tiles
in this situation. The garage is a one car garage how do I remedy this
situation? Just pop up all the tiles one by one until I work myself to
the edge of the "separation" and retile?
Answer:
Could oil beneath the tile "evaporate" due to heat, creating the "space"
and apparent air pressure release you observed? One of the strangest
things I've heard of. I'd check the level of both surfaces, to try to
get an idea of which seems to "move". Being in the land of sinkholes,
that possibility would be hard to ignore. Mebbe the city would come out
and have a look. As I learned exploring a different kind of problem,
city may have one of their civil engineers examine the problem, since it
is so odd. I'd also be inclined to pull up more tiles around the one
where you started to see how far the void extends - or slide a flat
metal yardstick under that tile to see how far. Any signs of
depressions anywhere in yard? If in center of garage, mebbe there was
an opening left for a drain but the drain covered/not installed?
The concrete would also slope if there is/was a drain and the genius who
put tile in the garage would not be bright enough to leave an opening in
the tile and wanted the tile floor level? Used it as a family room
and didn't put weight on the area in question, so's they didn't discover
how their brainstorm was defective?
