BAL, what we have here is a "Watter hammer". This is caused when the water is flowing thriugh the pipes at a given speed, then it is stopped so fast that the pipes shake. Purchase a hammer arrestor from your local plumbing store and install it on the COLD water line at the bathroom under the house. Problem solved. I am a VA licensed plumber and we have to install these quite a bit on new construction homes. Espesialy on the washing machine. Hope this helps.