I got used to moving buildings around a lot, mostly woodcutter camps, by selecting the building and hitting (m).
After a few runs I tried to move a Human House from one Hearth to another for the upgrade and it wouldn't let me, confused I tried to click the button and saw the tooltip said the move costs 5 wood. There's no indication other than hovering and reading the tooltip that this move would cost resources compared to other buildings which allow movement for free.
I think it would be good to have some UI change that would indicate if there was a cost, maybe a different coloured button or just the cost stated next to the button. I'm not sure the best way.
I even made a suggestion ingame about moving should not be free because it makes game too easy because I though all movement were free because non UI was mentionning it and I discovered it later the same way you did.
It took me a while to notice this as well. Maybe make a little symbol of the resource cost next to the move button?
only housing and farm buildings cost resources to move, camps, decorations and the 3 basic buildings (crude workstation, makeshift post, field kitchen) are free to move.
The button itself already states the cost, so it sounds like its mainly an issue if you're using hotkeys for it a lot. Maybe some kind of error message or sound effect when you hit the hotkey and can't afford the move would help.
Well it doesn't state anywhere that only housing and farms cost, that's just something you have to work out. Also the button does not state the cost, the tooltip from hovering over the button states it, easy to miss even if you were to click it.