I did bathroom reno and replaced bathtub and shower faucets locations and extended copper pipes a little. That's not the first time I weld copper pipes and I didn't have any problems in past. What I noticed Is that when I turn off the water (cold or hot) I hear knocking like pipes knock on something. I examined all the places where I changed the plumbing and everything looks secure and doesn't touch anything. But I feel that knocking inside the pipes. It's like a pressure issue inside.
Probably it was before my work. I recently bought the house but it annoys me. Should I be concerned about it and can that knocking damage my pluming?