Cutting and casting in floor in high-rise?

[henks]

Hello,

I would like to install floor spots indoors in a 1940s high-rise building.
However, I need to chisel into the floor to install them and the cable.

The floor consists of a 3cm concrete slab resting on sand that is at least 7-10cm deep.
In the staircase, it seems like the floor should be about 20-25cm before reaching the neighbor below.

I think it should be fine to chisel in for cables and spots as long as you refill the sand, do not cut rebar, and pour concrete again.

Is there anyone here with experience in renovation work who can share their opinion?
Do you then use coarse concrete to pour again?

 

[myrstack]

It sounds suspiciously thin with a 3cm slab on this layer of sand, are you sure the construction looks like this?

 

[henks]

This is what it looks like by a door frame that I've removed anyway.
I will drill a few holes and see if it's the same in other places.

 

[henks]

Seems to be a cake of 4-6cm, then there is filler material in the form of sand and small stones.

 

[danbanan2]

They used to build like that before, with a thicker slab first, then insulation made of sand, and then a thinner layer of concrete on top. The problem is that the bottom slab is not sturdy enough to support everything on its own, so both slabs are load-bearing. You could probably chisel a bit in the top one but not make long channels crisscrossing the apartment, as it would lose too much load-bearing capacity. If that's the case, I wouldn't chisel at all. It's better to lay 16mm pipes on the floor and use 18mm of self-leveling compound on top instead.