How do I Use the Repair Hammer?

-I’m on Xbox in a PvE server. -

Okay, this might sound really dumb but I’ve been searching and trying to figure this out for the last few days with no resolution.

I have a number of structures that are near decay, and I have the repair hammer, the supplies to rebuild the structures, I just can’t figure out how to do it.

Do I smash them with the repair hammer? I do that and nothing happens. Do I have to wait for it to be completely decayed? I’ve had some things disappear when I’ve done that. Is my repair hammer the wrong level for the structure?

Any help would be great.