Cutting the floor slab due to incorrectly placed drainage pipes

Hello everyone,

I am new to this forum and a bit desperate today regarding our house construction. We are currently building a single-family bungalow with an architect and individual awarding of contracts. The base slab and masonry are being done by the same company. Today, the first outer row of bricks was placed on the base slab. It was then discovered that the 3 drain pipes from the guest WC (sink, toilet, shower) were all set 70cm too far to the left. The drains from the toilet and sink are now in the hallway, and the one from the shower is directly in front of the WC door. The architect says this is not such a big deal. For the sink and toilet pipes, they want to cut open the slab and move the pipes 70cm to the correct location (inside the slab). There is apparently some other solution for the shower. The architect says this is not a structural issue. It should be mentioned that we do not have strip foundations but a subsoil of 25cm foam glass gravel and then a 25cm load-bearing base slab with WU concrete. I am paying the architect also for service phase 8 (construction supervision), and yet something like this happens, that can't be right. He said when he looked at it, there was no formwork board for the slab at that spot yet, so he couldn't measure it when he was there. Of course, he measured everything else beforehand. What can and must I do now? Is it really that harmless? What rights do I have, what do I have to pay attention to so as not to make a formal error? Deficiency notification? Documentation? Demand new structural calculations? Do I have to accept it as it is? Why make a 25cm slab with steel if you can then easily remove parts of it again without concern?

Best regards
Heiko

I am also paying the architect for service phase 8 (construction supervision) and something like this still happens, that can’t be. He said when he looked at it, there was no shuttering board for the slab at that spot yet, so he couldn’t measure it when he was there. Of course, he measured everything else before.

Sleepyheads alert. You’re going to have a lot of fun with that guy...

Well, it’s obviously annoying, but I don’t see the drama here. You don’t need a new structural analysis just because of moving some pipes. Why is the architect solely to blame? If the plans were correct, it was first the shell builder or whoever laid the pipes there who messed up. Sure, the architect has to notice, but mistakes can happen.

Can it still be installed in the later floor construction? What is planned there? Therefore, the panel may not need to be milled so deep.

Otherwise, the floor in the bathroom could, if necessary, also be raised by 7-10 cm depending on the planned pipe thickness (wooden construction) and thus create an "underground connection level." Disadvantage: step when entering the bathroom. Since a pipe comes out in the hallway, that’s also awkward, especially as it is the 100 mm toilet pipe. That means possibly using a cutting tool from 100 to an existing 50 mm? Would be an emergency solution.

: You can't be serious, thinking about something like that at all in a new building? I would consider both suggestions only as an absolute last resort, even in a renovation of an old building...

Alternative? New structural engineering report, legal dispute to clarify responsibility, report after report, and continuation of construction in 2025...

I do understand TE already that he does not want to cut into the 25cm floor slab including reinforcement with a 10cm deep channel.