My utility room is over a crawl space. Its a wood floor that is kinda of bouncy. My son tried to shore up the floor using some of the ideas on this forum.

However, there is still a slight bounce, enough that you walk right next to the water heater the heater vibrates a bit. When the washing machine goes into the spin it also shakes the heater slightly for a moment. Its only noticable when you have a bubble level sitting on top of the water heater and you see the bubble move a bit when walking around the unit.

Do you think it is normal to have some deflection as I describe with a wood floor and a heavy item?

I notice my refrigerator has the same very slight vibration too when I walk past it in the kitchen.