Bathroom renovation, new wastewater pipes on the other side of the room

Hello, we are buying a house and want to renovate the bathroom, which includes a breakthrough to the adjacent room.

In the old bathroom, the shower and toilet remain in their current positions. The sink will be removed, meaning the original drain will be used.

Since the other side of the room is too far away to extend a pipe there, we thought we would run a drain pipe from the kitchen under the new room section upwards.

I think there is no ventilation for the drain pipe on this side of the building. See picture (original pipes in red - new ones in green).

How can I, if we extend the pipes upwards and connect a bathtub + double washbasin, do we certainly need ventilation? Can this be done using a valve inside the room? Or is it necessary at all here?

Thanks in advance. :)

No, you don’t need any ventilation anymore. 20-30 years ago, a separate ventilation was still installed over the shower or similar. Today, modern fittings are directly equipped with ventilation, just ask in the specialist trade about it...

I think you are talking past each other. The OP means wastewater ventilation and you mean fresh water ventilation.

@OP: yes, you might need one. From the picture, the kitchen is just connected to the main vent stack (depends on the pipe diameter to the kitchen and the length).

Since a main vent is present according to your plan, a vent valve will most likely be sufficient for the branch line.

Ah yes, that may be :P This is the disadvantage of written words, they are often misunderstood or not read properly.