Quick answer
Rattling pipes inside walls are loose clips letting the pipe move, water hammer from fast-closing valves, or thermal expansion in long copper runs creaking as they warm and cool. Timing tells you which: noise on tap closure is hammer, noise while hot water runs is expansion, and noise whenever water flows at all is usually a clip that has come loose.
Common causes
- Loose or missing pipe clips inside the wall cavity
- Water hammer from fast-closing taps or appliance solenoid valves
- Thermal expansion in long copper runs rubbing against a joist or brick
- High mains pressure amplifying every one of the above
- Pipe passing through a tight hole with no sleeve or padding
- Notched joist letting the pipe drum against timber
What you can do now
- 1Note exactly when it happens — on tap closure, while hot water runs, or whenever water flows
- 2Tighten any accessible clips in the roof space, under cupboards and in the sub-floor
- 3Measure mains pressure, since high pressure makes every cause worse
- 4Close taps more slowly as a test to confirm or rule out hammer
- 5Note whether it started after other work, which often points at a disturbed clip
When to call a professional
Persistent rattling inside a cavity needs access, so it is worth combining with any renovation rather than opening a wall specially. In the meantime a plumber can fit a hammer arrestor or a pressure-reducing valve, which addresses the most common driver without opening anything. Do not leave it indefinitely — a pipe free to move works its joints loose over the years.
Typical cost in Johannesburg
Minor: hammer arrestor R650 · Major: wall access varies
Indicative ranges only. We provide written, itemised quotes before any work.
Related services
Need a Plumber or Electrician Today?
Owner-managed by Garth Blair. We pick up the phone and book you in personally.