Reply To: Knocking Sound in Wall? Home › Forums › Public Forums › General Plumbing › Knocking Sound in Wall? › Reply To: Knocking Sound in Wall? 12 Jun 2003 at 4:27 pm #294595 Retired plbg1Participant If you have PVC drains and hot water goes down them they expan and make a noise also the water pipes make a noise in the studs if holes are to small, all you can do is cut into wall and see where the noise is comming from and cut holes bigger.
