A pipe leaking inside a wall shows as a damp patch, blistering paint or a stain that returns after every repaint. The wet spot is where water arrives, not where the pipe failed.
This page is about pipes inside wall cavities and chases. For leaks under floors, in slabs and in ceilings, see hidden leak detection, or Leak Detection Cape Town for the full range.
A photo of the damp patch and which room is on the other side is enough to start.
Get an In-Wall Leak QuoteIs It a Pipe or Is It Damp
| Clue | Points to |
|---|---|
| Constant, unrelated to weather | A pipe in the wall. |
| Warm to the touch | A hot water line. Isolate the geyser. |
| Worse after rain, on an outside wall | Penetrating damp, not plumbing. |
| Even tide mark under a metre, with salts | Rising damp. |
| Meter moves with all taps closed | A pipe, somewhere. Detection narrows it. |
How an In-Wall Leak Is Located
- Moisture mapping - readings across the wall to find the wettest point, which is closer to the source than the visible stain.
- Thermal imaging - a hot line inside a wall warms the plaster in a traceable line.
- Pressure testing - isolate hot and cold separately to prove which one is failing.
- Acoustic tracing - listening along the chase on a pressurised line.
- Borescope - a camera through one small hole rather than an opened wall.
In-Wall Leak Detection Prices in Cape Town
| Job | Indicative range | What moves it |
|---|---|---|
| In-wall leak detection | R1,450 – R3,000 | Call-out plus the first hour. |
| Thermal imaging of the wall | R1,200 – R2,800 | Best on hot water lines. |
| Moisture mapping and report | R900 – R2,200 | Maps the true wet extent. |
| Pressure test, hot and cold separately | R850 – R1,900 | Proves which line fails. |
| Borescope inspection | R650 – R1,800 | One small hole instead of an opening. |
| Opening a plastered wall | R750 – R1,600 | Excludes making good. |
| Opening a tiled wall | R1,200 – R2,400 | Excludes replacement tiles. |
| In-wall pipe repair | R1,750 – R2,500 | Excludes plaster and tiling. |
| Replastering and repaint | R450 – R1,200 per m² | Once the wall has dried. |
| Retiling | R450 – R1,200 per m² | Matching discontinued tiles costs more. |
These are indicative market ranges, not a quotation. They are compiled from published South African leak detection and plumbing pricing to give you a starting point for budgeting. They are not the rate card of any company on this platform.
Do not repaint until the source is fixed and the wall has dried, which usually takes one to three weeks. Sealing a damp wall traps the moisture and the stain returns in the same place.
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Frequently Asked Questions
Can a leak inside a wall be found without breaking it open?
Yes. Thermal imaging, moisture meters, pressure testing and acoustic tracing all work through plaster and tile. Only the confirmed point is opened, for the repair.
Why is the damp patch not where the pipe turns out to be?
Water runs down the inside of the cavity and along the plaster until it finds a way out, so it can surface a metre or more below and to the side of the actual failure.
How do I know it is a pipe and not rising damp?
Timing. A pipe leaks constantly regardless of weather; rising damp and penetrating damp change with rain and season. A meter test with all taps closed settles it in 15 minutes.
Does the whole wall have to be re-plumbed?
Not usually. A single failure in sound copper or poly is a section repair. Corroded galvanised is different, since the rest of that run is at a similar stage and will fail again.
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