There's mould on the bottom of my walls
Mould, bubbling paint, crumbling plaster or a tide mark along the bottom of a wall means moisture is getting in from somewhere. Sometimes it's ventilation or ground moisture, but very often it's plumbing: a leaking shower, a pipe in the wall or a failed seal behind a vanity. Cleaning the mould off only treats the symptom. Finding where the water comes from is what stops it returning.
Plumbing causes we find
Leaking shower
Water escaping through worn grout, a failed waterproofing membrane or a leaking shower mixer soaks into the wall on the other side, often a bedroom or hallway.
Pipe leak inside the wall
A pinhole leak or failed joint in a water pipe can keep the bottom of a wall damp for months before it's noticed.
Leaking waste pipe
A cracked or loose waste pipe from a basin, bath or washing machine leaks every time it's used.
Outside drainage
Downpipes that discharge against the house, blocked stormwater, or garden beds built up against the wall can push water into the base of the wall.
Signs it's a plumbing leak
- The damp is next to or behind a bathroom, kitchen or laundry.
- It gets worse after showers or when certain fixtures are used.
- Your water meter moves when everything is turned off. See our hidden water leak guide.
- Skirting boards are swelling or tiles near the floor are lifting.
How we find it
We pressure test the water pipes, check the fixtures and waste pipes, and use moisture meters and thermal imaging to trace the damp to its source without opening up walls on a guess. If it's outside drainage, we look at the downpipes and stormwater too. Then you get clear options and a fixed price before any work starts. See leak detection.
In southern Eastern Suburbs homes
Older brick homes in Matraville, Maroubra and Kingsford often have original bathrooms where the waterproofing behind the tiles has failed, and copper or galvanised pipes in the walls that develop pinhole leaks. We regularly trace mould on a bedroom wall back to the shower on the other side.
Why locals call us
- Local to Matraville and the southern Eastern Suburbs
- Free on-site quotes, with a fixed price before any work starts
- Lifetime labour warranty on our workmanship
- 100+ five-star Google reviews
- Licensed plumbers and gasfitters (Lic. 398171C)
Common questions
Why is there mould at the bottom of my walls?
Moisture is getting into the wall, often from a leaking shower, pipe or waste pipe, or from poor drainage outside.
Can a leaking shower cause mould in the next room?
Yes. Water escaping through grout or failed waterproofing soaks through the wall into the room next door.
How do you find a leak behind a wall?
With pressure testing, moisture meters and thermal imaging, which pinpoint the source before any wall is opened.
Will cleaning the mould fix it?
Only for a while. Unless the moisture source is fixed, the mould will come back.
Related help: leak detection, hidden water leak guide, mould on the ceiling, I can hear water running and stormwater. Local pages: Matraville, Maroubra, Kingsford and Coogee.