This is indeed a difficult question for many. So, all communications are located either in the foundation or in the screed, with the exception of electricians for lighting and ventilation.
Laying communications in houses from CLT
This article describes the location of all necessary communications, starting from the bottom layer up.
The very first (bottom) layer is the sewer. It is laid either under a reinforced concrete slab, or, if the foundation is piled, under a heater. All sewer pipes are laid with a slope, so the water does not stagnate in them.
This is followed by water supply, it includes laying pipes for hot water and its circulation, as well as pipes for cold water.
If the foundation is UShP, then the water supply pipes are laid directly on the insulation under the foundation. If a screed is planned, then they are poured into the screed.
In the case of a pile foundation, they are also laid on a heater to avoid possible freezing.
Pipe outlets are hidden in furniture or behind false plasterboard walls.
The next layer is heating pipes. They are laid on a reinforcing mesh.
The last fit electrician for outlets. The wires rise 200 mm into the sockets in open gates. Strobs are made with a cutter along a ruler. Then the strobes are closed with glazing beads and painted over.
Electrics for lighting and ventilation are laid on the ceiling. In the future, these communications are hidden under a false ceiling - stretch or plasterboard.
The height of the walls of the house depends on the thickness of the screed and the space for ventilation on the ceiling. Therefore, it is very important to correctly lay the height of the walls in the project, otherwise the height of the final ceiling may be much lower than planned.
In an example, it looks like this. If the foundation of the UWB and the desired height of the finishing ceiling is 3,000 mm, then the height of the walls is initially 3300 mm, plus another 150-200 mm must be added to the screed.
In the photo you can see an example of laying the main communications, the sewerage is not visible here, since it is under the foundation.