I am still cheaper than if it is done completely by a general contractor. As I said, I didn't want to overdo it. In other words, I am allowed to buy the materials myself and prepare most of it. An electrician checks and approves it. So additional costs are minimal.
And I wonder if the coal, which you mostly get from the bank as interest, wouldn’t be better invested elsewhere?
Example? If I make only 2 sockets instead of 5, I don’t necessarily save copper cable, but 3 empty boxes (3x19 cents), some plaster and 3 sockets (about 15 euros).
If I later needed an extension cable or something similar, I would have to calculate what such an extension cable costs. Flush-mounted installation is probably not more expensive than surface-mounted, if I offset the surface-mounted conduit. Except if simple clamps are used.
Ventilation was just a “question”. Only one wallbox is being installed now.