I'll take stories like this all day to keep my vibrations up!

The fan is making a strong vibration that the upstairs bathroom is shaking, feels like a small earthquake.

Fan is vibrating too much that the second floor shakes.

My only concern would be to leave a little space for play/vibration.

Vibration can cause parts to come loose.

At the threshold you may need to lay something down when you're in there.Think about the noise source as vibration source and try to isolate that from things that will pass along the vibration or even amplify it.

Found generic "adjustable appliance feet", plus an "non-vibration rubber cushion" under each corner.

I'm not sure how well those materials would stand up to the vibrational load of driving the house anywhere.Plan for an extra .25-.50" of floor thickness.Radiant floor take hours to heat up.

They are loud and always fighting late at night, always banging on the walls, playing music and video games so loud that it vibrates the walls.

I've seen something similar before, it turned out that a few of the neutrals in the electrical panel weren't tightened down well enough on the ground bar and walking around in the house literally vibrated the wires enough to separate the connection.