Correct procedure: wall breakthrough & floor slab

Hi everyone,

we are currently renovating a small 90 sqm house from 1905 from the ground up. We are doing a lot of the work ourselves, but of course we have also consulted a structural engineer.
The ground floor has already been excavated to a depth of 60 cm and is getting a completely new floor structure including a new slab.
Furthermore, we have to rebuild the only load-bearing wall because it is very dilapidated. It will also get a 250 cm wide wall opening (with a steel beam).

Now the question:
What comes first – the chicken or the egg? :)
Would you first pour the slab and temporarily support the ceiling "floating," that is, with cross beams screwed to the walls, or would you first build the load-bearing wall on the ground and then pour everything with concrete?
For your information: The house has a footprint of only about 6.5 x 7 meters.

A thousand thanks for your answers!
Frida & Peter

That should be answered by the structural engineer. Because if a load-bearing wall, the load transfer to the foundation must also be provided. This is done either via a corresponding strip foundation underneath or via a correspondingly reinforced slab.

Streifenfundament == lay bricks beforehand
bewehrte Bodenplatte == lay bricks afterward.

Thank you, ! We will follow up with the structural engineer once again. But that has already helped.

I am hearing about supporting the ceiling with "firmly screwed crossbeams" for the first time. How is that supposed to work?

If the walls to which the beam(s) are to be screwed in are capable of supporting the ceiling, the newly to be built wall would be unnecessary. Because then you could simply rest the beam there. Are you sure you have spoken to a structural engineer? ;-)

Regarding the question: At the moment, I don’t see how the floor slab should be poured continuously without at least embedding the (in my opinion necessary) supports for the ceiling into the concrete. So it will probably come down to rebuilding the load-bearing wall in sections.

Hi Dr. Hix,
thanks for the reply!
The structural engineer said that the beams themselves could also last a while without a load-bearing wall/steel beam. The house is really very small.
However, the important point is to prevent a house of cards effect. A temporary crossbeam, we thought, might serve this purpose - at least until the foundation has dried and the new wall & steel beam for the wall opening have been installed.

It's probably best if we talk calmly with the structural engineer again. Somehow, we didn't get proper information about it at the last appointment.

Best regards!

Apart from the load-bearing function in this case, walls of course often also have a bracing function. However, I do not see this at all with a beam under the ceiling.

Either masonry on both sides at a right angle to the walls to be braced, or masonry-backed steel supports. I understand that the bracing can be temporarily omitted – the loads to be absorbed there, such as wind, do not occur permanently. How this is supposed to proceed without damage with the ceiling and the permanently acting weight is beyond my understanding.