Mould Low on Walls & Skirtings
Black or green mould creeping up from the skirting board isn’t a cleaning problem — it’s a moisture problem. Here’s what’s feeding it and how we stop it.
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Why mould keeps coming back
Mould needs three things to grow: moisture, a food source and still air. When you see mould low on walls, behind furniture or along skirtings, it’s telling you a wall or the space behind it is holding damp. On ground-floor Inner West walls that damp is often rising damp; where it clusters near the floor and comes with a musty smell, a poorly ventilated sub-floor may be feeding it from below. Bleaching the surface kills what you can see but does nothing about the moisture, so it regrows. The lasting fix is to remove the water — with a rising damp treatment if it’s coming through the wall, or subfloor ventilation if it’s rising from underneath. It often appears with a tide mark and a damp, musty smell.
How damp walls grow mould — and how we stop it
Hit play. Watch moisture rise into the lower wall where mould takes hold, then see a new damp course cut it off so the wall dries and the mould loses its water supply.
The wall starts dry
Press play to watch how ground moisture climbs a solid brick wall — and exactly what a new damp course changes.
What’s feeding the mould
Mould low on a wall is a moisture signal. Remove the moisture and the mould has nothing to live on.
Signs it’s damp-driven mould
Moisture-fed mould usually shows two or three of these.
Black spotting near the floor
Growth concentrated low on walls and skirtings.
Behind furniture
Worse in still corners and behind wardrobes.
Returns after cleaning
Regrows within weeks of being wiped or bleached.
With a tide mark
Appearing alongside a rising-damp stain.
On skirtings & timber
Spreading onto the timber at the base of the wall.
Musty smell
A damp odour around the affected area.
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What Inner West homeowners say about our damp & ventilation work.
“Inner West Rising Damp treated rising damp affecting several lower walls in our Croydon property and everything was handled professionally.”
“Mould problems in one bedroom completely disappeared after the works were completed.”
“The house constantly felt humid downstairs before the ventilation work was done.”
Two problems, two solutions
Mould low on the wall can be fed from the wall or from under the floor — here’s how we tell.
Rising damp treatment
If moisture is wicking up through the walls — tide marks, salt, bubbling plaster — you need a new damp course, not just airflow. We diagnose and install it.
Rising damp treatment →Subfloor ventilation
If the damp air is trapped under the house — musty floors, mould, condensation — you need ventilation to move it out and keep the space dry.
Subfloor ventilation →Mould FAQs
Why does the mould come back after I clean it?
Is it from the wall or under the floor?
Do you remove the mould as well?
Can mould affect my health?
Mould keeps coming back? Fix the cause
We’ll find whether it’s rising damp or sub-floor moisture feeding it, treat the source and give you a free, fixed quote.
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