ᐅ Retrofitting a Bathroom Ventilation System with Heat Recovery

Hello everyone,

We built our house last year without a ventilation system and are quite satisfied with that.

Only in the bathroom, due to my wife’s long showers, there is often a noticeably increased humidity level. This, in turn, requires frequent airing, which makes the bathroom too cold for my wife 🙄

We are now considering retrofitting a ventilation system in the bathroom. We would like to install it on one of the two exterior walls. Power supply is available in the attic directly above.

We understand that a core drill hole will be necessary. However, we would prefer to run the electrical wiring either inside the wall or along the outside of the wall up to the attic. The reason is that the interior plaster is finished and nicely painted. On the outside, only the base coat plaster has been applied so far. There, we could simply chase a groove and then fill it again with base coat plaster. I am aware that this will create a small thermal bridge.

Has anyone done or arranged something like this before?
Are there any experiences or recommendations for specific devices?
Is the electrical wiring as described above possible?

Thank you very much 🙂