I live in an apt on the first floor. Failry new construction. When the folks above me use what I believe is their sink each morning, I get a very loud ‘knocking’ in the wall–like someone punching the wall every 20 seconds or so. It appears to me that when they put their sink on, putting my ear to the wall I can hear the water come down the pipes, and more subtle knocking or ticking. But then after the sink is turned off, the noise seems to get much louder, for about 15 more minutes. This is every morning. BUT, when my apt’s maintenance crew sent someone to the upstairs apt to turn faucets on, we couldn’t hear it in my unit–this was at 12 noon, so I don’t know if it is something that can cause this to happen only cause their sink is used once per day, or water. Air in the pipes, water hammer come to mind. Any advice/tips?
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.