Is it allowed for the water pipe to be in the floor slab?

Hello.

We are getting a floor slab with an 80cm frost skirt. This is probably done this way in almost every construction. If I understand correctly, the skirt prevents water from getting under the slab and then freezing. Floor slab not insulated.

The water pipes are laid on top of the floor slab (insulated) and do not freeze and break. What happens if the pipes are embedded in the concrete, with insulation. Would the pipes freeze and break in this case?

It’s not about whether it makes sense to lay the pipes there, just the question above.

Thank you.

Without insulation = can break, With insulation = does not break, unless it reaches minus 100 degrees.

Without insulation = can break, with insulation = does not break, unless it gets to minus 100 degrees.

Well. Insulation does not warm, it only delays.

Whether your assessment survives two weeks of winter vacation (= stagnation in the pipe), I wouldn't be so sure.
Whether the tensile forces in the concrete leave the pipes intact is the next question. The pipe should be specified for this installation, including the pressure on the pipe.

Of course, the question of meaningfulness arises ;-)

In my bathroom (which is currently being built), a prospective architect also suggested placing the drain IN the floor. That would be practical, but the slope would be minimal - if there is any at all - and that would require a reliable and skilled craftsman to do it. I decided against it because of the slope problem. The pipes will be laid in front of the wall in a box about 1.20 m high, which takes up space and is therefore inconvenient, but that's probably how we'll do it ...

... and that’s actually how all the installers I know do it.

Without insulation = can break, with insulation = does not break, unless it gets minus 100 degrees.

Are you sure about that?

Whether the tensile forces in the concrete would keep the pipes intact is the next question. The pipe should be specified for this installation, including what pressure it can handle.

It should be like that. Many also install metal composite pipes in ceilings for heating and cooling.

Of course, the question of sensibility arises ;-)

Less pipe on the floor, better insulation.

In my bathroom (which is currently being built), a prospective architect also suggested placing the drain INTO the floor.
That would be practical, but the slope would be minimal – if there even was one – and that would require a reliable and good craftsman to do it.
Because of the slope problem, I decided against it. The pipes will be installed in front of the wall in a box about 1.20 m high, which takes up space and is therefore annoying, but that’s probably how we’ll do it...

With you, it’s about the sewage pipe, with me about the water pipe.
I would never do it above the floor if another option is possible.

... and that’s actually how all the plumbers I know do it.

I think that looks, well, bad.
Especially such ledges in the bathroom collect dust; I don’t want that :)
All pipes will be laid directly under the floor slab.