Plumbing noise in wall

[Chuck A.]

Hi

Looking for some advice. I have a condo unit where the pipes in the wall recently started making a knocking noise every time the water is used. Seems when the tenant flushes the toilet or runs the shower. Any ideas ?

Thanks

Chuck

[Erik B.]

Brian gave you some solid info. I'll add to it.

if the pipes are loose you need to secure. Can you get to the pipes from the basement or attic? Sometimes you can secure them from there. You can also slide pipe foam up or down the pipe. Foam will keep them from making noise but may not stop all the movement. 

If this is bathroom wet wall you may gain a visual access behind shower faucet cover plate.