Why does the floor of a terrace crack?

Roots can crack any masonary surface if it is not thick enough. It could also be ground movement if the temperatures vary considerably from summer to winter. This is why buildings have footers that go below frost level.

Neither. Poor landscaping or the ill aimed poop of a passing critter. Roots destroy all concrete and the best rule of thumb is to plant nothing of substantial size within 20 feet of any slab or wall. The roots work like a small chisel and pry up and grow. Unfortunately this causes pressure and over substantial time the weight of the displaced concrete will cause a crack. Driveways Sidewalks Foundations andyes even terraces all take the toll. Sorry but it is how it is.

Can you elaborate your question? Is the terrace slab near a large tree (within the dripline of the foliage?) similarly you found the "wall raised"? at that location also being displaced (up or laterally)? Where are you located? How old is the complex - approximately? What type of floor (slab or raised wood)?

poor compaction on the soil before it was poured,and not enough base material to support the weight of the slab of concrete. Setting is also a reason ,the concrete could have been poured where the the ground had been dozed and the builder didn't wait the year he was supposed to before he started building. The concrete may have been poured to thin to support the weight of the load on the floor. Concrete steel may have not been put in the floor before it was poured and caused the the floor to be too weak to support the weight on the floor.

It sounds as if your floor caved in, which is why it's lower than the wall. Do you have earthquakes?

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