Drain pipe up to downpipe experiences

Hello,

we are converting the attic and also planning a bathroom with a bathtub, double sink, and toilet.
The risers were already extended three years ago during the bathroom renovation.
However, we are now wondering how to handle the drains up to the [Fallrohr].
The outlet of the bathtub will be around 5.00m. According to my research, the slope should be around 1cm/m1.
Since there is no continuous wall up to the [Fallrohr], the drain pipe (9cm diameter?) would have to go through the subfloor up to the [Fallrohr]?

Or how should this be done?

Thanks for your experiences!

They are embedded in the screed.
Lay the pipe with the appropriate slope and then the screed is applied.

First, you have to determine which connection pipe each object requires – for a bathtub, DN50 would usually be used. But this is also difficult to impossible to accommodate in the screed with a slope over such a distance. It depends on the overall floor construction – perhaps something can be accommodated in the attic structure if beams or similar are not in the way?

Ideally, you arrange the sanitary fixtures so that smaller connection pipes are combined, so that the largest diameter only occurs near the soil pipe, and preferably everything is then accommodated in (e.g. drywall) walls. It doesn't necessarily have to be routed along the most direct path, although bends always represent a weak point.

They are embedded in the screed. Laying pipe with the appropriate slope

We had an apartment built in 1972, where the screed would not have been sufficient for that. In the bathrooms, the ceilings of the apartments below were suspended and the pipes were laid under the ceilings. With a length of 5m, that already adds up to more height than can disappear in a screed.

In our bathroom, we had a similar problem. The pipes were then routed along the outside of the wall up to the downpipe, I estimate it was about 4 meters, with two 90° bends. Bathtub, toilet, and washbasin. In our case, it could be well concealed behind enclosures (toilet cistern, etc.). If necessary, the craftsman would have also covered the visible pipe for us, but it was not needed at all.