ᐅ Experience with drain pipes up to the downpipe

Hello,

we are converting the attic and planning to install a bathroom with a bathtub, double sink, and toilet.
The soil and vent pipes were already extended during the bathroom renovation three years ago.
However, we are now wondering how to connect the drains to the stack.
The bathtub drain will be about 5.00 m (16.4 ft) long. From my research, the slope should be around 1 cm/m (0.4 inch/ft).
Since there is no continuous wall running to the stack pipe, should the drainpipe (9 cm diameter (3.5 inches)?) run through the subfloor to reach the stack?

Or how should this be done?

Thanks for your input!

They are embedded in the screed.
The pipe is laid with the appropriate slope, and then the screed is applied on top.

First, you need to determine what type of connection pipe each fixture requires – for a bathtub, a DN50 (2-inch) pipe is usually used. However, installing such a pipe with the required slope in the screed over that distance is difficult to impossible. It depends on the overall floor construction – it might be possible to route something through the attic structure if beams or similar obstructions are not in the way.

Ideally, you position the sanitary fixtures so that smaller connection pipes can be combined, resulting in the largest diameter pipe only near the main soil stack. Whenever possible, these pipes should be integrated into walls, for example, drywall partitions. The pipes do not always have to follow the shortest path, although bends and turns are potential weak points in the system.

ypg schrieb:

They are embedded in the screed.
Pipe installation with the appropriate slope

We had an apartment built in 1972 where the screed wouldn’t have been sufficient for that. In the bathrooms, the ceilings of the apartments below were lowered, and the piping was installed above those ceilings. With a length of 5 m (16 ft), that adds up to more height than can be concealed in a screed.

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We had a similar issue in our bathroom. The pipes were routed along the outside of the wall up to the soil pipe, which I estimate was about 4 meters (13 feet), with two 90° bends. Bathtub, toilet, and sink. In our case, this could be nicely concealed behind built-in units (toilet cistern, etc.). If necessary, the contractor would have also boxed in the visible pipe, but that wasn’t needed at all.