Opening or breaking up the floor slab possible - any experiences?

Hello everyone,

unfortunately, our wastewater pipes are now partially outside the dimensions in the floor slab.

Now the idea came up to open the floor slab in the area of the 10 KG pipes DN 100 and to install Hauff connection funnels AT 100 there. These will then be cast in when the openings are closed.

Setting aside the costs, is it unproblematic to open the floor slab? Can the floor slab sustain major damage or does chiseling not cause any issues? Is a new structural analysis or other documents needed for this?

Is it even feasible to install the connection funnels retroactively (the funnels have a diameter of 360 mm), the area that needs to be chiseled is thus not really small.

Thank you very much for your help

Now the idea came up

Who had the idea? Did the site manager take a look at it now or did the idea come up at your place on Saturday evening at 10 p.m.?

You know that this is a question/a problem for professionals, not for builders!

And, I would definitely consult with the prefab house provider as well.

Yes, the site manager has looked at it. However, he has little interest because the floor slab is considered "owner's work" and he does not assess the floor slab professionally. The floor slab builder has submitted a specialist site manager declaration, and with that, everything is done for the site manager.

At the meeting yesterday at the floor slab, the floor slab builder said that the slab would just be broken open.

But I have some doubts and question that as the client.

I am looking for the best solution. Although I find the connection funnels a clean solution, I have some doubts with 10 openings of this size.

According to the floor slab builder, "everything is no problem" and you can just do everything like that. But he already said that before and then did it wrong.

Yes, the site manager has looked at it. However, he is not very interested because the foundation slab is an "own contribution" and he does not professionally assess the foundation slab.

He is not supposed to professionally assess it either, but rather to specify exactly which connections actually need to be installed. And then check the contract with the foundation slab builder. Did he have the correct drawings, etc.? Whether the solution is technically sound can probably only be told to you by an expert.

There he is again