Regarding the "cat" thing, I don't specifically require Cat6. I just need a reliable gigabit connection between my living room and the bedrooms area. So far I've had powerlines and mesh wifi, and I'm not happy with either (patchy and only delivering around 100Mbps).
At the moment, for a completely unrelated reason, we have our living room floor removed and will take some time to restore. This gives me access behind the plasterboard so I'm taking the opportunity to lay ethernet cable. (You can argue that I could have laid it anyway above the skirting, but that would not have passed the domestic redecorations approval committee
). The cable will go behind the wall plasterboard (see photo for an idea, I put a different cable there just to demonstrate),
then run in front of that concrete step, then behind plasterboard again, then in a wall cavity, and then behind that wooden board on the wall (see photo).
It won't be possible to have conduit for the whole cable journey (I attach a photo of the cavity which was a real challenge to insert the cable alone),
but I will try to put one for the part in front of the concrete step and have the flooring finish just before it.
Regarding cat* certification: I don't specifically need Cat6, I'm pretty sure that cat5e is enough, and I am considering Cat6 in order to overshoot. I understand that without proper installation, the Cat6 won't live up to its specs, but I won't need the full specs. Will it be at least as good as cat5e though with a chance of being better? (Whatever that means, more reliable, less heat dissipation from PoE, etc). If yes, I'll go for cat6 for this one cable, as it will be more difficult to replace it.