Dare I post a picture of something that the majority has criticized?
Everything went well during the floor construction. The little problem I encountered was the floor slope to the drain, but I was aware of that and solved it with spacers under the joists where needed. What made me continue is that we have a sauna in the same room which (of course...) is also made of wood and stands on the floor, and it still looks fine since it was built in 2006.
I thought my solution turned out better than the one with tiles that Danne_08 linked to, but thanks anyway for the tips and ideas!